Originally Posted by ashtonsser 
Ive always used Mobil 1 15w-50 Synthetic and if you saw what my crank and bearings looked like after the beating I gave my motor for a year and 12k miles, 8k rev limit, hit 11k+ a couple times during gear breakages, 450whp daily 550whp on weekends and at the strip. Every day beat on to death pounding the limiter 1st-4th. Yeah you wouldnt say Mobil 1 is crap. 12k miles and the bearings looked like the day I put them in, not a mark on the crank, still polished like the day I put it in.
I hear good things about Rotella but Im a Mobil 1 15w50 lover and always will be until it proves otherwise. But soo far I have nothing but praise for it.
Yes but do you remember what clearances you were running for that oil? I'd run pretty loose clearances on mains and rods with that oil, definately not OE spec with that thick of oil. Shoot me a PM if you don't want to reveal your numbers. If its a competition engine that almost always rides in the upper RPMs I run loose all around (drifting), if its a daily engine, I still with OEM tightness, if it's for drag racing one size larger (OEM +.0002") on mains than OEM, and then loose on the rods (.0018-.0020). Seems to work well so far with what I have done.
Thicker oil means that you have to watch the temps, you can't rev it when its cold, the oil has to be warmed up fully, which is not good for drifting since the cars are only on running on the track at high RPM for only a minute or so and then are either idling or just shut off and wait for the next round. Drag racing is kinda the same, but not in high RPMs for a long time, but still the oil will probably be warmed up before someone goes all out. I'll have to try the 15W50 Mobil in my next engine, I usually run 20W50 on the older NA SRs that aren't refreshed and then 10w40 on newer engines. In summer, winter oils should be pretty thin like 10W30 for Texas at least.
I think oil temps are pretty important for bearing life and I see more and more cars coming with oil temp indicators that are turboed, so just a thought if you guys are racing and experience bearing wear on fresh rebuilds.
Last edited by David NA->FI
on 2012-02-15
at 15-35-23.
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