Personally on NA I run 10W-30

Forced induction I go higher some times as high as 20W-50 if there is alot of heat in the set up.


BTW, even the guys I watched drag racing with more then .002 bearing clearance blow the motors. I believe they shoot for .0025 and eventually it beats the bearings up.

Based on my observations, My theory is that the oil is only a lubricant and the force exerted on the rods under WOT can push that oil out the sides and displace it under heavy load. With the larger clearance's the rod is actually moving around causing the crank to literally beat on the bearings. The one's I have seen torn down after failure, the bearings are pretty thrashed and worse case a rod goes through the side of the block.

Maybe in a Top fuel Engine running a loser tolerance to reduce friction is fine because they constantly rebuild the engines. But something that your trying to get some years out of just doesn't seem to work to well from what I have seen.

 

thats true.

but i run 15w40 Delo 400 oil for diesels.. i seen big trucks go over a million miles with it and they run those things hard so the oil has to be decent

 

Thanks for the responses I feel way better now running everything the way I have it.. Didn't want to go head strong into it without a good consensus and find a flaw that could otherwise have been overlooked!