Originally Posted By: JAG
Originally Posted By: Mitch Alsup
Modern engines are designed for 8 cSt of operating viscosity, the 1990s high performance engines {Ferrari, Prosche, BMW} are designed for 12 cSt of operating viscosity.
That makes no sense to me. How did you come to those conclusions?
via aehaas articles, and BITOG topics several years ago. It just so happens that these are the viscosities of engines using 0W-20 oils at operating conditions.
Quote:
Originally Posted By: Mitch Alsup
Originally Posted By: opposite_locker
Not true. Newer european cars REQUIRE an HT/HS of >3.5
a: only when the engine is being pushed hard and for long periods of time (like HPDE driving) where the oil gets as hot as 290dF+
The OEM requirements in question for HTHS viscosity do not have a hard-driving type stipulation.
Yes, but in the car I have with similar performance (Ferrari F355B) the only way to get the oil up into the temperature range where HTHS numbers are applicable (>260dF) is to drive the living snot out of it on real race tracks. It is simply notpossible to get the oil up above 230dF even in 103dF ambients (Texas) in city traffic or on back road romps. The only way to get the oil temps this high is sustained 100% throttle for more than 5 minutes. Even using a lower gear and reving the snot out of it at 8250 RPMs will not get the oil over 245dF unless the throttle is also 100% down.
Now, maybe the F355B has a lot more oil cooling than the BMW M cars--I don't know, and maybe the finger followers add to the HTHS or operating viscosities above and beyond those of my (lowly) ferrari. I suspect that that the finger followers would really like a higher dose of ZDDP than SM oils anyway (high load wiping action lubrication).