My 01 rk started blowing at about 30k mi at 75mph. After 10k mi and a lot of consulting I heard the cam chain tensioners wear premature. I went into it and they were worn down to the chain and the material had clogged the oil pump. Cleaned it out and replaced with stock tensioners and that fixed it cheap. The more expensive fix is replace with hydraulic tensioner kit has cam plate tensioners and better pump. Hope this is helpful.