Lubricant
Encyclopedia
A lubricant is a substance introduced to reduce friction
between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat. The property of reducing friction is known as lubricity
.
A good lubricant possesses the following characteristics:
One of the single largest applications for lubricants, in the form of motor oil
, is protecting the internal combustion engine
s in motor vehicles and powered equipment.
Typically lubricants contain 90% base oil (most often petroleum
fractions, called mineral oil
s) and less than 10% additives
. Vegetable oils or synthetic liquids such as hydrogenated polyolefin
s, ester
s, silicone
s, fluorocarbon
s and many others are sometimes used as base oils. Additives deliver reduced friction and wear, increased viscosity
, improved viscosity index, resistance to corrosion
and oxidation, aging or contamination, etc.
Lubricants such as 2-cycle oil are added to fuel
s like gasoline which has low lubricity. Sulfur
impurities in fuels also provide some lubrication properties, which has to be taken in account when switching to a low-sulfur diesel; biodiesel
is a popular diesel fuel additive providing additional lubricity.
Non-liquid lubricants include grease
, powders (dry graphite
, PTFE
, Molybdenum disulfide
, tungsten disulfide, etc.), teflon tape used in plumbing, air cushion and others. Dry lubricant
s such as graphite, molybdenum disulfide and tungsten disulfide also offer lubrication at temperatures (up to 350 °C) higher than liquid and oil-based lubricants are able to operate. Limited interest has been shown in low friction properties of compacted oxide glaze layers formed at several hundred degrees Celsius in metallic sliding systems, however, practical use is still many years away due to their physically unstable nature.
Another approach to reducing friction and wear is to use bearings
such as ball bearing
s, roller bearings or air bearings, which in turn require internal lubrication themselves, or to use sound, in the case of acoustic lubrication
.
In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking (oil
s and fat
s in use in frying pan
s, in baking to prevent food sticking), bio-medical applications on humans (e.g. lubricants for artificial joint
s), ultrasound examination, internal examinations for males and females, and the use of personal lubricant
for sexual purposes.
in a system. This has the benefit of reducing friction and surface fatigue, together with reduced heat generation, operating noise and vibrations. Lubricants achieve this by several ways. The most common is by forming a physical barrier i.e., a thin layer of lubricant separates the moving parts. This is analogous to hydroplaning, the loss of friction observed when a car tire is separated from the road surface by moving through standing water. This is termed hydrodynamic lubrication. In cases of high surface pressures or temperatures, the fluid film is much thinner and some of the forces are transmitted between the surfaces through the lubricant.
is much less than surface-to-surface friction in a system without any lubrication. Thus use of a lubricant reduces the overall system friction. Reduced friction has the benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. Lubricants may contain additives
known as friction modifiers that chemically bind to metal surfaces to reduce surface friction even when there is insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve train in a car engine at startup.
. Typically the liquid lubricant is constantly circulated to and from a cooler part of the system, although lubricants may be used to warm as well as to cool when a regulated temperature is required. This circulating flow also determines the amount of heat that is carried away in any given unit of time. High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant. Thus lower cost liquid lubricants may be used. The primary drawback is that high flows typically require larger sumps and bigger cooling units. A secondary drawback is that a high flow system that relies on the flow rate to protect the lubricant from thermal stress is susceptible to catastrophic failure during sudden system shut downs. An automotive oil-cooled turbocharger
is a typical example. Turbochargers get red hot during operation and the oil that is cooling them only survives as its residence time in the system is very short i.e. high flow rate. If the system is shut down suddenly (pulling into a service area after a high speed drive and stopping the engine) the oil that is in the turbo charger immediately oxidizes and will clog the oil ways with deposits. Over time these deposits can completely block the oil ways, reducing the cooling with the result that the turbo charger experiences total failure typically with seized bearings
.
Non-flowing lubricants such as greases & pastes are not effective at heat transfer although they do contribute by reducing the generation of heat in the first place.
It is apparent that in a circulatory system the oil will only be as clean as the filter can make it, thus it is unfortunate that there are no industry standards by which consumers can readily assess the filtering ability of various automotive filters. Poor filtration significantly reduces the life of the machine (engine) as well as making the system inefficient.
are used as the working fluid
in hydrostatic power transmission. Hydraulic fluids comprise a large portion of all lubricants produced in the world. The automatic transmission
's torque converter
is another important application for power transmission with lubricants.
s), liquid and solid lubricants dominate the market, especially the former.
Lubricants are generally composed of a majority of base oil
plus a variety of additives to impart desirable characteristics. Although generally lubricants are based on one type of base oil, mixtures of the base oils also are used to meet performance requirements.
(API) designates several types of lubricant base oil:
The lubricant industry commonly extends this group terminology to include:
Can also be classified into three categories depending on the prevailing compositions:
, palm oil
, sunflower seed oil and rapeseed oil from vegetable, and Tall oil
from tree sources. Many vegetable oils are often hydrolyzed to yield the acids which are subsequently combined selectively to form specialist synthetic esters. Other naturally derived lubricants include lanolin
(wool grease, a natural water repellent).
Whale oil
was an historically important lubricant, with some uses up to the latter part of the 20th century as a friction modifier additive
for automatic transmission fluid
.
In 2008, the biolubricant market was around 1% of UK lubricant sales in a total lubricant market of 840,000 tonnes/year.
Lanolin
is a natural water repellent, derived from sheep wool grease, and is an alternative to the more common petro-chemical based lubricants. This lubricant is also a corrosion inhibitor, protecting against rust, salts, and acids.
Water
can also be used on its own, or as a major component in combination with one of the other base oils. Commonly used in engineering processes, such as milling and lathe turning.
(PTFE) is typically used as a coating layer on, for example, cooking utensils to provide a non-stick surface. Its usable temperature range up to 350 °C and chemical inertness make it a useful additive in special greases. Under extreme pressures, teflon powder or solids is of little value as it is soft and flows away from the area of contact. Ceramic or metal or alloy lubricants must be used then.
Inorganic solids: Graphite
, hexagonal boron nitride
, molybdenum disulfide
and tungsten disulfide are examples of materials that can be used as solid lubricants, often to very high temperature. The use of some such materials is sometimes restricted by their poor resistance to oxidation (e.g., molybdenum disulfide can only be used up to 350°C in air, but 1100°C in reducing environments).
Metal/alloy: Metal alloys, composites and pure metals can be used as grease additives or the sole constituents of sliding surfaces and bearings. Cadmium
and Gold
are used for plating surfaces which gives them good corrosion resistance and sliding properties, Lead
, Tin
, Zinc
alloys and various Bronze
alloys are used as sliding bearings, or their powder can be used to lubricate sliding surfaces alone, or as additives to greases.
formation. This is the generation of a compacted oxide layer which sinters together to form a crystalline 'glaze' (not the amorphous layer seen in pottery) generally at high temperatures, from metallic surfaces sliding against each other (or a metallic surface against a ceramic surface). Due to the elimination of metallic contact and adhesion by the generation of oxide, friction and wear is reduced. Effectively, such a surface is self-lubricating.
As the 'glaze' is already an oxide, it can survive to very high temperatures in air or oxidising environments. However, it is disadvantaged by it being necessary for the base metal (or ceramic) having to undergo some wear first to generate sufficient oxide debris.
Note that many of the basic chemical compounds used as detergents (example: calcium sulfonate) serve the purpose of the first seven items in the list as well. Usually it is not economically or technically feasible to use a single do-it-all additive compound. Oils for hypoid gear lubrication will contain high content of EP additives. Grease lubricants may contain large amount of solid particle friction modifiers, such as graphite, molybdenum sulfide.
The lubricant is said to meet a certain specification. In the consumer market, this is often supported by a logo, symbol or words that inform the consumer that the lubricant marketer has obtained independent verification of conformance to the specification. Examples of these include the API’s donut logo or the NSF
tick mark. The most widely perceived is SAE viscosity specification, like SAE 10W-40. Lubricity specifications are institute and manufacturer based. In the U.S. institute: API S for petrol engines, API C for diesel engines. For 2007 the current specs are API SM and API CJ-4. Higher second letter marks better oil properties, like lower engine wear supported by tests. In EU the ACEA specifications are used. There are classes A, B, C, E with number following the letter. Japan introduced the JASO specification for motorbike engines.
In the industrial market place the specification may take the form of a legal contract to supply a conforming fluid or purchasers may choose to buy on the basis of a manufacturers own published specification.
Specifications often denote a minimum acceptable performance levels. Thus many equipment manufacturers add on their own particular requirements or tighten the tolerance on a general specification to meet their particular needs (or doing a different set of tests or using different/own testbed engine). This gives the lubricant marketer an avenue to differentiate their product by designing it to meet an OEM specification. Often, the OEM carries out extensive testing and maintains an active list of approved products. This is a powerful marketing tool in the lubricant marketplace. Text on the back of the motor oil label usually has a list of conformity to some OEM specifications, such as MB, MAN, Volvo, Cummins, VW, BMW or others. Manufactures may have vastly different specifications for the range of engines they make; one may not be completely suitable for some other.
The lubricant marketer claims benefits for the customer based on the superior performance of the lubricant. Such marketing is supported by glamorous advertising, sponsorships of typically sporting events and endorsements. Unfortunately broad performance claims are common in the consumer marketplace, which are difficult or impossible for a typical consumer to verify. In the B2B market place the marketer is normally expected to show data that supports the claims, hence reducing the use of broad claims. Increasing performance, reducing wear and fuel consumption is also aim of the later API, ACEA and car manufacturer oil specifications, so lubricant marketers can back their claims by doing extensive (and expensive) testing.
The marketer claims that their lubricant maintains its performance over a longer period of time. For example in the consumer market, a typical motor oil change interval is around the 3000 –. The lubricant marketer may offer a lubricant that lasts for 12000 miles (19,312 km) or more to convince a user to pay a premium. Typically, the consumer would need to check or balance the longer life and any warranties offered by the lubricant manufacturer with the possible loss of equipment manufacturer warranties by not following its schedule. Many car and engine manufacturers support extended drain intervals, but request extended drain interval certified oil used in that case; and sometimes a special oil filter. Example: In older Mercedes-Benz engines and in truck engines one can use engine oil MB 228.1 for basic drain interval. Engine oils conforming with higher specification MB 228.3 may be used twice as long, oil of MB 228.5 specification 3x longer. Note that the oil drain interval is valid for new engine with fuel conforming car manufacturer specification. When using lower grade fuel, or worn engine the oil change interval has to shorten accordingly. In general oils approved for extended use are of higher specification and reduce wear.
In the industrial market place the longevity is generally measured in time units and the lubricant marketer can suffer large financial penalties if their claims are not substantiated.
The lubricant marketer claims improved equipment efficiency when compared to rival products or technologies, the claim is usually valid when comparing lubricant of higher specification with previous grade. Typically the efficiency is proved by showing a reduction in energy costs to operate the system. Guaranteeing improved efficiency is the goal of some oil test specifications such as API
CI-4 Plus for diesel engines. Some car/engine manufacturers also specifically request certain higher efficiency level for lubricants for extended drain intervals.
The lubricant is claimed to cope with specific operational environment needs. Some common environments include dry, wet, cold, hot, fire risk, high load, high or low speed, chemical compatibility, atmospheric compatibility, pressure or vacuum and various combinations. The usual thermal characteristics is outlined with SAE viscosity given for 100°C, like SAE 30, SAE 40. For low temperature viscosity the SAE xxW mark is used. Both markings can be combined together to form a SAE 0W-60 for example. Viscosity index
(VI) marks viscosity change with temperature, with higher VI numbers being more temperature stable.
The marketer offers a lubricant at a lower cost than rivals either in the same grade or a similar one that will fill the purpose for lesser price. (Stationary installations with short drain intervals.) Alternative may be offering a more expensive lubricant and promise return in lower wear, specific fuel consumption or longer drain intervals. (Expensive machinery, un-affordable downtimes.)
The lubricant is said to be environmentally friendly. Typically this is supported by qualifying statements or conformance to generally accepted approvals. Several organizations, typically government sponsored, exist globally to qualify and approve such lubricants by evaluating their potential for environmental harm. Typically, the lubricant manufacturer is allowed to indicate such approval by showing some special mark. Examples include the German “Blue Angel
”, European “Daisy
” Eco label, Global Eco-Label “GEN mark”, Nordic, “White Swan”, Japanese “Earth friendly mark”; USA “Green Seal”, Canadian “Environmental Choice”, Chinese “Huan”, Singapore “Green Label” and the French “NF Environment mark”.
The marketer claims novel composition of the lubricant which improves some tangible performance over its rivals. Typically the technology is protected via formal patents or other intellectual property protection mechanism to prevent rivals from copying. Lot of claims in this area are simple marketing buzzwords, since most of them are related to a manufacturer specific process naming (which achieves similar results than other ones) but the competition is prohibited from using a trademark.
The marketer claims broad superior quality of its lubricant with no factual evidence. The quality is “proven” by references to famous brand, sporting figure, racing team, some professional endorsement or some similar subjective claim. All motor oil labels wear mark similar to "of outstanding quality" or "quality additives," the actual comparative evidence is always lacking.
Disposal:
Recycling
, burning, landfill
and discharge into water may achieve disposal of used lubricant.
There are typically strict regulations in most countries regarding disposal in landfill and discharge into water as even small amount of lubricant can contaminate a large amount of water. Most regulations permit a threshold level of lubricant that may be present in waste streams and companies spend hundreds of millions of dollars annually in treating their waste waters to get to acceptable levels.
Burning the lubricant as fuel, typically to generate electricity, is also governed by regulations mainly on account of the relatively high level of additives present. Burning generates both airborne pollutants and ash rich in toxic materials, mainly heavy metal compounds. Thus lubricant burning takes place in specialized facilities that have incorporated special scrubbers to remove airborne pollutants and have access to landfill sites with permits to handle the toxic ash.
Unfortunately, most lubricant that ends up directly in the environment is due to general public discharging it onto the ground, into drains and directly into landfills as trash. Other direct contamination sources include runoff from roadways, accidental spillages, natural or man-made disasters and pipeline leakages.
Improvement in filtration technologies and processes has now made recycling a viable option (with rising price of base stock and crude oil). Typically various filtration systems remove particulates, additives and oxidation products and recover the base oil. The oil may get refined during the process. This base oil is then treated much the same as virgin base oil however there is considerable reluctance to use recycled oils as they are generally considered inferior. Basestock fractionally vacuum distilled from used lubricants has superior properties to all natural oils, but cost effectiveness depends on many factors. Used lubricant may also be used as refinery feedstock to become part of crude oil. Again there is considerable reluctance to this use as the additives, soot and wear metals will seriously poison/deactivate the critical catalysts in the process. Cost prohibits carrying out both filtration (soot, additives removal) and re-refining (distilling, isomerisation, hydrocrack, etc.) however the primary hindrance to recycling still remains the collection of fluids as refineries need continuous supply in amounts measured in cisterns, rail tanks.
Occasionally, unused lubricant requires disposal. The best course of action in such situations is to return it to the manufacturer where it can be processed as a part of fresh batches.
Environment:
Lubricants both fresh and used can cause considerable damage to the environment mainly due to their high potential of serious water pollution. Further the additives typically contained in lubricant can be toxic to flora and fauna. In used fluids the oxidation products can be toxic as well. Lubricant persistence in the environment largely depends upon the base fluid, however if very toxic additives are used they may negatively affect the persistence. Lanolin
lubricants are non-toxic making them the environmental alternative which is safe for both users and the environment.
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat. The property of reducing friction is known as lubricity
Lubricity
Lubricity is the measure of the reduction in friction of a lubricant. The study of lubrication and mechanism wear is called tribology.-Measurement of lubricity:...
.
A good lubricant possesses the following characteristics:
- High boiling point.
- Low freezing point.
- High viscosity indexViscosity indexViscosity index is an arbitrary measure for the change of viscosity with temperature. It is used to characterize lubricating oil in the automotive industry....
. - Thermal stability.
- Corrosion prevention.
- High resistance to oxidation.
One of the single largest applications for lubricants, in the form of motor oil
Motor oil
Motor oil or engine oil is an oil used for lubrication of various internal combustion engines. The main function is to lubricate moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts.Motor oils are derived from...
, is protecting the internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
s in motor vehicles and powered equipment.
Typically lubricants contain 90% base oil (most often petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
fractions, called mineral oil
Mineral oil
A mineral oil is any of various colorless, odorless, light mixtures of alkanes in the C15 to C40 range from a non-vegetable source, particularly a distillate of petroleum....
s) and less than 10% additives
Oil additive
Oil additives are chemical compounds that improve the lubricant performance of base oil . By utilizing the same base stock, many different oils can be manufactured, each with its distinctive properties. Additives comprise up to 5% by weight of some oils.Nearly all commercial motor oils contain...
. Vegetable oils or synthetic liquids such as hydrogenated polyolefin
Polyolefin
A polyolefin is a polymer produced from a simple olefin as a monomer. For example, polyethylene is the polyolefin produced by polymerizing the olefin ethylene. An equivalent term is polyalkene; this is a more modern term, although polyolefin is still used in the petrochemical industry...
s, ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s, silicone
Silicone
Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications , cookware, and insulation....
s, fluorocarbon
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
s and many others are sometimes used as base oils. Additives deliver reduced friction and wear, increased viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
, improved viscosity index, resistance to corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
and oxidation, aging or contamination, etc.
Lubricants such as 2-cycle oil are added to fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
s like gasoline which has low lubricity. Sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
impurities in fuels also provide some lubrication properties, which has to be taken in account when switching to a low-sulfur diesel; biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
is a popular diesel fuel additive providing additional lubricity.
Non-liquid lubricants include grease
Grease (lubricant)
The term grease is used to describe semisolid lubricants. Although the word grease is also used to describe rendered fat of animals, in the context of lubrication, grease typically applies to a material consisting of a soap emulsified with mineral or vegetable oil...
, powders (dry graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
, PTFE
Polytetrafluoroethylene
Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....
, Molybdenum disulfide
Molybdenum disulfide
Molybdenum disulfide is the inorganic compound with the formula MoS2. This black crystalline sulfide of molybdenum occurs as the mineral molybdenite. It is the principal ore from which molybdenum metal is extracted. The natural amorphous form is known as the rarer mineral jordisite. MoS2 is less...
, tungsten disulfide, etc.), teflon tape used in plumbing, air cushion and others. Dry lubricant
Dry lubricant
Dry lubricants or solid lubricants are materials which despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid media....
s such as graphite, molybdenum disulfide and tungsten disulfide also offer lubrication at temperatures (up to 350 °C) higher than liquid and oil-based lubricants are able to operate. Limited interest has been shown in low friction properties of compacted oxide glaze layers formed at several hundred degrees Celsius in metallic sliding systems, however, practical use is still many years away due to their physically unstable nature.
Another approach to reducing friction and wear is to use bearings
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
such as ball bearing
Ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit...
s, roller bearings or air bearings, which in turn require internal lubrication themselves, or to use sound, in the case of acoustic lubrication
Acoustic lubrication
Acoustic or sonic lubrication occurs when sound permits vibration to introduce separation between the sliding faces. This could happen between two plates or between a series of particles...
.
In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking (oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
s and fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
s in use in frying pan
Frying pan
A frying pan, frypan, or skillet is a flat-bottomed pan used for frying, searing, and browning foods. It is typically in diameter with relatively low sides that flare outwards, a long handle, and no lid. Larger pans may have a small grab handle opposite the main handle...
s, in baking to prevent food sticking), bio-medical applications on humans (e.g. lubricants for artificial joint
Replacement joint
Replacement arthroplasty [from Greek arthron, joint, limb, articulate, + -plassein, to form, mould, forge, feign, make an image of], or joint replacement surgery, is a procedure of orthopedic surgery in which the arthritic or dysfunctional joint surface is replaced with an orthopaedic prosthesis...
s), ultrasound examination, internal examinations for males and females, and the use of personal lubricant
Personal lubricant
Personal lubricants are specialized lubricants to reduce friction between body parts, or between body parts and other objects...
for sexual purposes.
Purpose
Lubricants perform the following key functions.- Keep moving parts apart
- Reduce friction
- Transfer heat
- Carry away contaminants & debris
- Transmit power
- Protect against wear
- Prevent corrosion
- Seal for gases
- Stop the risk of smoke and fire of objects
Keep moving parts apart
Lubricants are typically used to separate moving partsMoving parts
The moving parts of a machine are those parts of it that move. Machines comprise both moving and fixed parts. The moving parts have controlled and constrained motions....
in a system. This has the benefit of reducing friction and surface fatigue, together with reduced heat generation, operating noise and vibrations. Lubricants achieve this by several ways. The most common is by forming a physical barrier i.e., a thin layer of lubricant separates the moving parts. This is analogous to hydroplaning, the loss of friction observed when a car tire is separated from the road surface by moving through standing water. This is termed hydrodynamic lubrication. In cases of high surface pressures or temperatures, the fluid film is much thinner and some of the forces are transmitted between the surfaces through the lubricant.
Reduce friction
Typically the lubricant-to-surface frictionFriction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...
is much less than surface-to-surface friction in a system without any lubrication. Thus use of a lubricant reduces the overall system friction. Reduced friction has the benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. Lubricants may contain additives
Oil additive
Oil additives are chemical compounds that improve the lubricant performance of base oil . By utilizing the same base stock, many different oils can be manufactured, each with its distinctive properties. Additives comprise up to 5% by weight of some oils.Nearly all commercial motor oils contain...
known as friction modifiers that chemically bind to metal surfaces to reduce surface friction even when there is insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve train in a car engine at startup.
Transfer heat
Both gas and liquid lubricants can transfer heat. However, liquid lubricants are much more effective on account of their high specific heat capacityHeat capacity
Heat capacity , or thermal capacity, is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount...
. Typically the liquid lubricant is constantly circulated to and from a cooler part of the system, although lubricants may be used to warm as well as to cool when a regulated temperature is required. This circulating flow also determines the amount of heat that is carried away in any given unit of time. High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant. Thus lower cost liquid lubricants may be used. The primary drawback is that high flows typically require larger sumps and bigger cooling units. A secondary drawback is that a high flow system that relies on the flow rate to protect the lubricant from thermal stress is susceptible to catastrophic failure during sudden system shut downs. An automotive oil-cooled turbocharger
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
is a typical example. Turbochargers get red hot during operation and the oil that is cooling them only survives as its residence time in the system is very short i.e. high flow rate. If the system is shut down suddenly (pulling into a service area after a high speed drive and stopping the engine) the oil that is in the turbo charger immediately oxidizes and will clog the oil ways with deposits. Over time these deposits can completely block the oil ways, reducing the cooling with the result that the turbo charger experiences total failure typically with seized bearings
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
.
Non-flowing lubricants such as greases & pastes are not effective at heat transfer although they do contribute by reducing the generation of heat in the first place.
Carry away contaminants and debris
Lubricant circulation systems have the benefit of carrying away internally generated debris and external contaminants that get introduced into the system to a filter where they can be removed. Lubricants for machines that regularly generate debris or contaminants such as automotive engines typically contain detergent and dispersant additives to assist in debris and contaminant transport to the filter and removal. Over time the filter will get clogged and require cleaning or replacement, hence the recommendation to change a car's oil filter at the same time as changing the oil. In closed systems such as gear boxes the filter may be supplemented by a magnet to attract any iron fines that get created.It is apparent that in a circulatory system the oil will only be as clean as the filter can make it, thus it is unfortunate that there are no industry standards by which consumers can readily assess the filtering ability of various automotive filters. Poor filtration significantly reduces the life of the machine (engine) as well as making the system inefficient.
Transmit power
Lubricants known as hydraulic fluidHydraulic fluid
Hydraulic fluids, also called hydraulic liquids, are the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water...
are used as the working fluid
Working fluid
A working fluid is a pressurized gas or liquid that actuates a machine. Examples include steam in a steam engine, air in a hot air engine and hydraulic fluid in a hydraulic motor or hydraulic cylinder...
in hydrostatic power transmission. Hydraulic fluids comprise a large portion of all lubricants produced in the world. The automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
's torque converter
Torque converter
In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...
is another important application for power transmission with lubricants.
Protect against wear
Lubricants prevent wear by keeping the moving parts apart. Lubricants may also contain anti-wear or extreme pressure additives to boost their performance against wear and fatigue.Prevent corrosion
Good quality lubricants are typically formulated with additives that form chemical bonds with surfaces, or exclude moisture, to prevent corrosion and rust.Seal for gases
Lubricants will occupy the clearance between moving parts through the capillary force, thus sealing the clearance. This effect can be used to seal pistons and shafts.Types of lubricants
In 1999, an estimated 37,300,000 tons of lubricants were consumed worldwide. Automotive applications dominate, but other industrial, marine, and metal working applications are also big consumers of lubricants. Although air and other gas-based lubricants are known, e.g., in fluid bearingFluid bearing
Fluid bearings are bearings which support the bearing's loads solely on a thin layer of liquid or gas.They can be broadly classified as fluid dynamic bearings or hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and...
s), liquid and solid lubricants dominate the market, especially the former.
Lubricants are generally composed of a majority of base oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
plus a variety of additives to impart desirable characteristics. Although generally lubricants are based on one type of base oil, mixtures of the base oils also are used to meet performance requirements.
Base oil groups
Mineral oil term is used to encompass lubricating base oil derived from crude oil. The American Petroleum InstituteAmerican Petroleum Institute
The American Petroleum Institute, commonly referred to as API, is the largest U.S trade association for the oil and natural gas industry...
(API) designates several types of lubricant base oil:
- Group I – Saturates <90% and/or sulfurSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
>0.03%, and Society of Automotive Engineers (SAE) viscosity indexViscosity indexViscosity index is an arbitrary measure for the change of viscosity with temperature. It is used to characterize lubricating oil in the automotive industry....
(VI) of 80 to 120
- Manufactured by solvent extraction, solvent or catalytic dewaxing, and hydro-finishing processes. Common Group I base oil are 150SN (solvent neutral), 500SN, and 150BS (brightstock)
- Group II – Saturates over 90% and sulfur under 0.03%, and SAE viscosity index of 80 to 120
- Manufactured by hydrocracking and solvent or catalytic dewaxing processes. Group II base oil has superior anti-oxidation properties since virtually all hydrocarbon molecules are saturated. It has water-white color.
- Group III – Saturates > 90%, sulfur <0.03%, and SAE viscosity index over 120
- Manufactured by special processes such as isohydromerization. Can be manufactured from base oil or slax wax from dewaxing process.
- Group IV – Polyalphaolefins (PAO)
- Group V – All others not included above such as naphthenics, PAG, esterEsterEsters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s.
-
- In North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, Groups III, IV and V are now described as synthetic lubricantsSynthetic oilSynthetic oil is a lubricant consisting of chemical compounds that are artificially made . Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials...
, with group III frequently described as synthesised hydrocarbons, or SHCs. In EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, only Groups IV and V may be classed as synthetics.
- In North America
The lubricant industry commonly extends this group terminology to include:
- Group I+ with a Viscosity IndexViscosity indexViscosity index is an arbitrary measure for the change of viscosity with temperature. It is used to characterize lubricating oil in the automotive industry....
of 103–108 - Group II+ with a Viscosity Index of 113–119
- Group III+ with a Viscosity Index of at least 140
Can also be classified into three categories depending on the prevailing compositions:
- Paraffinic
- Naphthenic
- Aromatic
-
- Lubricants for internal combustion engines contain additives to reduce oxidation and improve lubrication. The main constituent of such lubricant product is called the base oil, base stock. While it is advantageous to have a high-grade base oil in a lubricant, proper selection of the lubricant additives is equally as important. Thus some poorly selected formulation of PAO lubricant may not last as long as more expensive formulation of Group III+ lubricant.
Biolubricants made from vegetable oils and other renewable sources
These are primarily triglyceride esters derived from plants and animals. For lubricant base oil use the vegetable derived materials are preferred. Common ones include high oleic canola oil, castor oilCastor oil
Castor oil is a vegetable oil obtained from the castor bean . Castor oil is a colorless to very pale yellow liquid with mild or no odor or taste. Its boiling point is and its density is 961 kg/m3...
, palm oil
Palm oil
Palm oil, coconut oil and palm kernel oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the fruit of the oil palm Elaeis guineensis; palm kernel oil is derived from the kernel of the oil palm and coconut oil is derived from the kernel of the...
, sunflower seed oil and rapeseed oil from vegetable, and Tall oil
Tall oil
Tall oil, also called "liquid rosin" or tallol, is a viscous yellow-black odorous liquid obtained as a by-product of the Kraft process of wood pulp manufacture when pulping mainly coniferous trees. The name originated as an anglicization of the Swedish "tallolja"...
from tree sources. Many vegetable oils are often hydrolyzed to yield the acids which are subsequently combined selectively to form specialist synthetic esters. Other naturally derived lubricants include lanolin
Lanolin
Lanolin , also called Adeps Lanae, wool wax or wool grease, is a yellow waxy substance secreted by the sebaceous glands of wool-bearing animals. Most lanolin used by humans comes from domestic sheep...
(wool grease, a natural water repellent).
Whale oil
Whale oil
Whale oil is the oil obtained from the blubber of various species of whales, particularly the three species of right whale and the bowhead whale prior to the modern era, as well as several other species of baleen whale...
was an historically important lubricant, with some uses up to the latter part of the 20th century as a friction modifier additive
Oil additive
Oil additives are chemical compounds that improve the lubricant performance of base oil . By utilizing the same base stock, many different oils can be manufactured, each with its distinctive properties. Additives comprise up to 5% by weight of some oils.Nearly all commercial motor oils contain...
for automatic transmission fluid
Automatic Transmission Fluid
Automatic transmission fluid is the fluid used in vehicles with self shifting or automatic transmissions. It is typically colored red or green to distinguish it from motor oil and other fluids in the vehicle...
.
In 2008, the biolubricant market was around 1% of UK lubricant sales in a total lubricant market of 840,000 tonnes/year.
Lanolin
Lanolin
Lanolin , also called Adeps Lanae, wool wax or wool grease, is a yellow waxy substance secreted by the sebaceous glands of wool-bearing animals. Most lanolin used by humans comes from domestic sheep...
is a natural water repellent, derived from sheep wool grease, and is an alternative to the more common petro-chemical based lubricants. This lubricant is also a corrosion inhibitor, protecting against rust, salts, and acids.
Water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
can also be used on its own, or as a major component in combination with one of the other base oils. Commonly used in engineering processes, such as milling and lathe turning.
Synthetic oils
- Polyalpha-olefin (PAO)
- Synthetic esters
- Polyalkylene glycols (PAG)
- Phosphate esters
- Alkylated naphthalenes (AN)
- Silicate esters
- Ionic fluids
Solid lubricants
Teflon or PTFE: TeflonPolytetrafluoroethylene
Polytetrafluoroethylene is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....
(PTFE) is typically used as a coating layer on, for example, cooking utensils to provide a non-stick surface. Its usable temperature range up to 350 °C and chemical inertness make it a useful additive in special greases. Under extreme pressures, teflon powder or solids is of little value as it is soft and flows away from the area of contact. Ceramic or metal or alloy lubricants must be used then.
Inorganic solids: Graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
, hexagonal boron nitride
Boron nitride
Boron nitride is a chemical compound with chemical formula BN, consisting of equal numbers of boron and nitrogen atoms. BN is isoelectronic to a similarly structured carbon lattice and thus exists in various crystalline forms...
, molybdenum disulfide
Molybdenum disulfide
Molybdenum disulfide is the inorganic compound with the formula MoS2. This black crystalline sulfide of molybdenum occurs as the mineral molybdenite. It is the principal ore from which molybdenum metal is extracted. The natural amorphous form is known as the rarer mineral jordisite. MoS2 is less...
and tungsten disulfide are examples of materials that can be used as solid lubricants, often to very high temperature. The use of some such materials is sometimes restricted by their poor resistance to oxidation (e.g., molybdenum disulfide can only be used up to 350°C in air, but 1100°C in reducing environments).
Metal/alloy: Metal alloys, composites and pure metals can be used as grease additives or the sole constituents of sliding surfaces and bearings. Cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
and Gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
are used for plating surfaces which gives them good corrosion resistance and sliding properties, Lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, Tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
, Zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
alloys and various Bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
alloys are used as sliding bearings, or their powder can be used to lubricate sliding surfaces alone, or as additives to greases.
'Glaze' formation (high temperature wear)
A further phenomenon that has undergone investigation in relation to high temperature wear prevention and lubrication, is that of a compacted oxide layer glazeCompacted oxide layer glaze
Compacted oxide layer glaze describes the often shiny, wear-protective layer of oxide formed when two metals are slid against each other at high temperature in an oxygen-containing atmosphere...
formation. This is the generation of a compacted oxide layer which sinters together to form a crystalline 'glaze' (not the amorphous layer seen in pottery) generally at high temperatures, from metallic surfaces sliding against each other (or a metallic surface against a ceramic surface). Due to the elimination of metallic contact and adhesion by the generation of oxide, friction and wear is reduced. Effectively, such a surface is self-lubricating.
As the 'glaze' is already an oxide, it can survive to very high temperatures in air or oxidising environments. However, it is disadvantaged by it being necessary for the base metal (or ceramic) having to undergo some wear first to generate sufficient oxide debris.
Additives
A large number of additives are used to impart performance characteristics to the lubricants. The main families of additives are:- AntioxidantAntioxidantAn antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
s - DetergentDetergentA detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
s - Anti-wearAW additiveAW additives, or antiwear additives, are additives for lubricants to prevent metal-to-metal contact between parts of gears.EP additives are usually used in applications such as gearboxes, while AW additives are used with lighter loads such as bushings....
- Metal deactivatorMetal deactivatorMetal deactivators, or metal deactivating agents are fuel additives and oil additives used to stabilize fluids by deactivating metal ions, mostly introduced by the action of naturally occurring acids in the fuel and acids generated in lubricants by oxidative processes with the metallic parts of...
s - Corrosion inhibitors, Rust inhibitors
- Friction modifierFriction modifierFriction modifiers are added to lubricants to reduce the surface friction of the lubricated parts. Typically these are polar chemical compounds having high affinity for metal surfaces and possessing long alkyl chains....
s - Extreme PressureEP additiveExtreme pressure additives, or EP additives, are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures...
- Anti-foaming agents
- Viscosity index improvers
- Demulsifying/EmulsifyingEmulsionAn emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...
- Stickiness improver, provide adhesive property towards tool surface (in metalworking)
- Complexing agent (in case of greases)
Note that many of the basic chemical compounds used as detergents (example: calcium sulfonate) serve the purpose of the first seven items in the list as well. Usually it is not economically or technically feasible to use a single do-it-all additive compound. Oils for hypoid gear lubrication will contain high content of EP additives. Grease lubricants may contain large amount of solid particle friction modifiers, such as graphite, molybdenum sulfide.
Application by fluid types
- Automotive
- Engine oils
- Petrol (GasolineGasolineGasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
) engine oils - Diesel engineDiesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
oils
- Petrol (Gasoline
- Automatic transmissionAutomatic transmissionAn automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...
fluid - Gearbox fluids
- Brake fluidBrake fluidBrake fluid is a type of hydraulic fluid used in hydraulic brake and hydraulic clutch applications in automobiles, motorcycles, light trucks, and some bicycles. It is used to transfer force into pressure...
s - Hydraulic fluidHydraulic fluidHydraulic fluids, also called hydraulic liquids, are the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water...
s
- Engine oils
- Tractor (one lubricant for all systems)
- Universal Tractor Transmission Oil – UTTO
- Super Tractor Oil Universal – STOU – includes engine
- Other motors
- 2-stroke engine oilsTwo-stroke oilTwo-stroke oil is an engine oil intended for use in two-stroke engines....
- 2-stroke engine oils
- Industrial
- Hydraulic oils
- Air compressor oils
- Gas CompressorGas compressorA gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
oils - GearGearA gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....
oils - Bearing and circulating system oils
- Refrigerator compressor oils
- Steam and gas turbine oils
- Aviation
- Gas turbineGas turbineA gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....
engine oils - Piston engine oils
- Gas turbine
- Marine
- Crosshead cylinder oils
- Crosshead CrankcaseCrankcaseIn an internal combustion engine of the reciprocating type, the crankcase is the housing for the crankshaft. The enclosure forms the largest cavity in the engine and is located below the cylinder, which in a multicylinder engine are usually integrated into one or several cylinder blocks...
oils - Trunk piston engine oils
- Stern tube lubricants
Marketing
The global lubricant market is generally competitive with numerous manufacturers and marketers. Overall the western market may be considered mature with a flat to declining overall volumes while there is strong growth in the emerging economies. The lubricant marketers generally pursue one or more of the following strategies when pursuing business.- Specification:
The lubricant is said to meet a certain specification. In the consumer market, this is often supported by a logo, symbol or words that inform the consumer that the lubricant marketer has obtained independent verification of conformance to the specification. Examples of these include the API’s donut logo or the NSF
NSF International
NSF International is an Ann Arbor, Michigan-based not-for-profit public health and environmental organization that provides standards development, product certification, auditing, education and risk management services.-History:...
tick mark. The most widely perceived is SAE viscosity specification, like SAE 10W-40. Lubricity specifications are institute and manufacturer based. In the U.S. institute: API S for petrol engines, API C for diesel engines. For 2007 the current specs are API SM and API CJ-4. Higher second letter marks better oil properties, like lower engine wear supported by tests. In EU the ACEA specifications are used. There are classes A, B, C, E with number following the letter. Japan introduced the JASO specification for motorbike engines.
In the industrial market place the specification may take the form of a legal contract to supply a conforming fluid or purchasers may choose to buy on the basis of a manufacturers own published specification.
- Original equipment manufacturer (OEM) approval:
Specifications often denote a minimum acceptable performance levels. Thus many equipment manufacturers add on their own particular requirements or tighten the tolerance on a general specification to meet their particular needs (or doing a different set of tests or using different/own testbed engine). This gives the lubricant marketer an avenue to differentiate their product by designing it to meet an OEM specification. Often, the OEM carries out extensive testing and maintains an active list of approved products. This is a powerful marketing tool in the lubricant marketplace. Text on the back of the motor oil label usually has a list of conformity to some OEM specifications, such as MB, MAN, Volvo, Cummins, VW, BMW or others. Manufactures may have vastly different specifications for the range of engines they make; one may not be completely suitable for some other.
- Performance:
The lubricant marketer claims benefits for the customer based on the superior performance of the lubricant. Such marketing is supported by glamorous advertising, sponsorships of typically sporting events and endorsements. Unfortunately broad performance claims are common in the consumer marketplace, which are difficult or impossible for a typical consumer to verify. In the B2B market place the marketer is normally expected to show data that supports the claims, hence reducing the use of broad claims. Increasing performance, reducing wear and fuel consumption is also aim of the later API, ACEA and car manufacturer oil specifications, so lubricant marketers can back their claims by doing extensive (and expensive) testing.
- Longevity:
The marketer claims that their lubricant maintains its performance over a longer period of time. For example in the consumer market, a typical motor oil change interval is around the 3000 –. The lubricant marketer may offer a lubricant that lasts for 12000 miles (19,312 km) or more to convince a user to pay a premium. Typically, the consumer would need to check or balance the longer life and any warranties offered by the lubricant manufacturer with the possible loss of equipment manufacturer warranties by not following its schedule. Many car and engine manufacturers support extended drain intervals, but request extended drain interval certified oil used in that case; and sometimes a special oil filter. Example: In older Mercedes-Benz engines and in truck engines one can use engine oil MB 228.1 for basic drain interval. Engine oils conforming with higher specification MB 228.3 may be used twice as long, oil of MB 228.5 specification 3x longer. Note that the oil drain interval is valid for new engine with fuel conforming car manufacturer specification. When using lower grade fuel, or worn engine the oil change interval has to shorten accordingly. In general oils approved for extended use are of higher specification and reduce wear.
In the industrial market place the longevity is generally measured in time units and the lubricant marketer can suffer large financial penalties if their claims are not substantiated.
- Efficiency:
The lubricant marketer claims improved equipment efficiency when compared to rival products or technologies, the claim is usually valid when comparing lubricant of higher specification with previous grade. Typically the efficiency is proved by showing a reduction in energy costs to operate the system. Guaranteeing improved efficiency is the goal of some oil test specifications such as API
American Petroleum Institute
The American Petroleum Institute, commonly referred to as API, is the largest U.S trade association for the oil and natural gas industry...
CI-4 Plus for diesel engines. Some car/engine manufacturers also specifically request certain higher efficiency level for lubricants for extended drain intervals.
- Operational tolerance:
The lubricant is claimed to cope with specific operational environment needs. Some common environments include dry, wet, cold, hot, fire risk, high load, high or low speed, chemical compatibility, atmospheric compatibility, pressure or vacuum and various combinations. The usual thermal characteristics is outlined with SAE viscosity given for 100°C, like SAE 30, SAE 40. For low temperature viscosity the SAE xxW mark is used. Both markings can be combined together to form a SAE 0W-60 for example. Viscosity index
Viscosity index
Viscosity index is an arbitrary measure for the change of viscosity with temperature. It is used to characterize lubricating oil in the automotive industry....
(VI) marks viscosity change with temperature, with higher VI numbers being more temperature stable.
- Economy:
The marketer offers a lubricant at a lower cost than rivals either in the same grade or a similar one that will fill the purpose for lesser price. (Stationary installations with short drain intervals.) Alternative may be offering a more expensive lubricant and promise return in lower wear, specific fuel consumption or longer drain intervals. (Expensive machinery, un-affordable downtimes.)
- Environment friendly:
The lubricant is said to be environmentally friendly. Typically this is supported by qualifying statements or conformance to generally accepted approvals. Several organizations, typically government sponsored, exist globally to qualify and approve such lubricants by evaluating their potential for environmental harm. Typically, the lubricant manufacturer is allowed to indicate such approval by showing some special mark. Examples include the German “Blue Angel
Blue Angel (certification)
The Blue Angel is a German certification for products and services that have environmentally friendly aspects.It has been awarded since 1978 by the Jury Umweltzeichen, a group of 13 persons from environment and consumer protection groups, industry, unions, trade, media and churches.Blue Angel is...
”, European “Daisy
Ecolabel
Ecolabels and Green Stickers are labelling systems for food and consumer products. Ecolabels are often voluntary, but Green Stickers are mandated by law in North America for major appliances and automobiles. They are a form of sustainability measurement directed at consumers, intended to make it...
” Eco label, Global Eco-Label “GEN mark”, Nordic, “White Swan”, Japanese “Earth friendly mark”; USA “Green Seal”, Canadian “Environmental Choice”, Chinese “Huan”, Singapore “Green Label” and the French “NF Environment mark”.
- Composition:
The marketer claims novel composition of the lubricant which improves some tangible performance over its rivals. Typically the technology is protected via formal patents or other intellectual property protection mechanism to prevent rivals from copying. Lot of claims in this area are simple marketing buzzwords, since most of them are related to a manufacturer specific process naming (which achieves similar results than other ones) but the competition is prohibited from using a trademark.
- Quality:
The marketer claims broad superior quality of its lubricant with no factual evidence. The quality is “proven” by references to famous brand, sporting figure, racing team, some professional endorsement or some similar subjective claim. All motor oil labels wear mark similar to "of outstanding quality" or "quality additives," the actual comparative evidence is always lacking.
Lubricant Testing
The global lubricant market is generally competitive with numerous manufacturers and marketers. Overall the western market may be considered mature with a flat to declining overall volumes while there is strong growth in the emerging economies. The lubricant marketers generally pursue one or more of the following strategies when pursuing business.Disposal and environmental issues
It is estimated that 40% of all lubricants are released into the environment.Disposal:
Recycling
Recycling
Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...
, burning, landfill
Landfill
A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
and discharge into water may achieve disposal of used lubricant.
There are typically strict regulations in most countries regarding disposal in landfill and discharge into water as even small amount of lubricant can contaminate a large amount of water. Most regulations permit a threshold level of lubricant that may be present in waste streams and companies spend hundreds of millions of dollars annually in treating their waste waters to get to acceptable levels.
Burning the lubricant as fuel, typically to generate electricity, is also governed by regulations mainly on account of the relatively high level of additives present. Burning generates both airborne pollutants and ash rich in toxic materials, mainly heavy metal compounds. Thus lubricant burning takes place in specialized facilities that have incorporated special scrubbers to remove airborne pollutants and have access to landfill sites with permits to handle the toxic ash.
Unfortunately, most lubricant that ends up directly in the environment is due to general public discharging it onto the ground, into drains and directly into landfills as trash. Other direct contamination sources include runoff from roadways, accidental spillages, natural or man-made disasters and pipeline leakages.
Improvement in filtration technologies and processes has now made recycling a viable option (with rising price of base stock and crude oil). Typically various filtration systems remove particulates, additives and oxidation products and recover the base oil. The oil may get refined during the process. This base oil is then treated much the same as virgin base oil however there is considerable reluctance to use recycled oils as they are generally considered inferior. Basestock fractionally vacuum distilled from used lubricants has superior properties to all natural oils, but cost effectiveness depends on many factors. Used lubricant may also be used as refinery feedstock to become part of crude oil. Again there is considerable reluctance to this use as the additives, soot and wear metals will seriously poison/deactivate the critical catalysts in the process. Cost prohibits carrying out both filtration (soot, additives removal) and re-refining (distilling, isomerisation, hydrocrack, etc.) however the primary hindrance to recycling still remains the collection of fluids as refineries need continuous supply in amounts measured in cisterns, rail tanks.
Occasionally, unused lubricant requires disposal. The best course of action in such situations is to return it to the manufacturer where it can be processed as a part of fresh batches.
Environment:
Lubricants both fresh and used can cause considerable damage to the environment mainly due to their high potential of serious water pollution. Further the additives typically contained in lubricant can be toxic to flora and fauna. In used fluids the oxidation products can be toxic as well. Lubricant persistence in the environment largely depends upon the base fluid, however if very toxic additives are used they may negatively affect the persistence. Lanolin
Lanolin
Lanolin , also called Adeps Lanae, wool wax or wool grease, is a yellow waxy substance secreted by the sebaceous glands of wool-bearing animals. Most lanolin used by humans comes from domestic sheep...
lubricants are non-toxic making them the environmental alternative which is safe for both users and the environment.
Societies and industry bodies
- American Petroleum InstituteAmerican Petroleum InstituteThe American Petroleum Institute, commonly referred to as API, is the largest U.S trade association for the oil and natural gas industry...
(API) - Society of Tribologists and Lubrication EngineersSociety of Tribologists and Lubrication Engineersor "STLE" is the premier technical society that serves the needs of more than 10,000 individuals and 150 companies and organizations that comprise the tribology and lubrication engineering business sector, bringing together managers, engineers, scientists, technicians, academics, and government...
(STLE) - National Lubricating Grease InstituteNational Lubricating Grease InstituteThe National Lubricating Grease Institute is an international trade association that serves the grease and gear lubricant industry. It exists to promote research and development of lubrication technology. It also publishes industry standards for greases....
(NLGI) - Society of Automotive Engineers (SAE)
- Independent Lubricant Manufacturer Association (ILMA)
- European Automobile Manufacturers AssociationEuropean Automobile Manufacturers AssociationThe European Automobile Manufacturers Association is the main lobbying and standards group of the automobile industry in the European Union. It is the follow on organization to CCMC in 1996....
(ACEA) - Japanese Automotive Standards OrganizationJapanese Automotive Standards OrganizationThe is an organization that sets automotive standards in Japan, analogous tothe Society of Automotive Engineers in the United States. JASO also sets standards for grades of oil; the highest grade for two-stroke engines being JASO FC, and JASO MA for four-stroke engines .JASO is part of the...
(JASO)
Major publications
- Peer reviewed
- Tribology Transactions
- Journal of Synthetic Lubricants
- Tribology Letters
- Lubrication Science
- Trade periodicals
- Tribology and Lubrication Technology
- Fuels & Lubes International
- Oiltrends
- Lubes n’ Greases
- Compoundings
- Chemical Market Review
- Machinery lubrication
See also
- Castor oilCastor oilCastor oil is a vegetable oil obtained from the castor bean . Castor oil is a colorless to very pale yellow liquid with mild or no odor or taste. Its boiling point is and its density is 961 kg/m3...
- Grease (lubricant)Grease (lubricant)The term grease is used to describe semisolid lubricants. Although the word grease is also used to describe rendered fat of animals, in the context of lubrication, grease typically applies to a material consisting of a soap emulsified with mineral or vegetable oil...
- LubricationLubricationLubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load between the opposing surfaces. The interposed...
- Mineral oilMineral oilA mineral oil is any of various colorless, odorless, light mixtures of alkanes in the C15 to C40 range from a non-vegetable source, particularly a distillate of petroleum....
s - Motor oilMotor oilMotor oil or engine oil is an oil used for lubrication of various internal combustion engines. The main function is to lubricate moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts.Motor oils are derived from...
- Oil analysisOil analysisOil analysis is the laboratory analysis of a lubricant's properties, suspended contaminants, and wear debris. OA is performed during routine preventive maintenance to provide meaningful and accurate information on lubricant and machine condition...
- Penetrating oilPenetrating oilPenetrating oil, also known as penetrating fluid, is very low-viscosity oil. It can be used to free rusted mechanical parts so that they can be removed, because it can penetrate into the narrow space between the threads of two parts. It can also be used as a general-purpose lubricant, a cleaner,...
- Personal lubricantPersonal lubricantPersonal lubricants are specialized lubricants to reduce friction between body parts, or between body parts and other objects...
- Society of Tribologists and Lubrication EngineersSociety of Tribologists and Lubrication Engineersor "STLE" is the premier technical society that serves the needs of more than 10,000 individuals and 150 companies and organizations that comprise the tribology and lubrication engineering business sector, bringing together managers, engineers, scientists, technicians, academics, and government...
- TribologyTribologyTribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear...
Sources
- API 1509, Engine Oil Licensing and Certification System, 15th Edition, 2002. Appendix E, API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils (revised)
- Boughton and Horvath, 2003, Environmental Assessment of Used Oil Management Methods, Environmental Science and Technology, V38
- I.A. Inman. Compacted Oxide Layer Formation under Conditions of Limited Debris Retention at the Wear Interface during High Temperature Sliding Wear of Superalloys, Ph.D. Thesis (2003), Northumbria University, ISBN 1-58112-321-3
- Mercedes-Benz oil recommendations, extracted from factory manuals and personal research
- Measuring reserve alkalinity and evaluation of wear dependence
- Testing used oil quality, list of possible measurements
- Lubricant Additives: Chemistry and Applications, Leslie R. Rudnick, CRC Press.