Originally Posted by oilman
Looking at the temps you guys have posted, there are a few cars where the oil isn't getting hot enough you want it to get over 70-80C as some of the additives require heat to work properly. You don't want to overcool the oil, 100C is ideal.
Also, the temps are generally within the safe tolerances for a quality 5w-40 (up to 130C average, with higher peaks). Perhaps with a forged build a 10w-50 would be better if the temp gets over 115C or it burns much oil.
On a hot-ish day (25C) with an HKS oil cooler located behind the passenger side indicator (removed the indicator for trackwork) I never got above 110C. However the engine dumped a lot of oil past my Mines head baffles and into the catch can and rear turbo inlet. It also does this on drag races with lower oil temps btw (turbo restrictor added btw).
Would I benefit from a thicker oil?
90000km never opened engine (as far as I know)
GTSS turbos 1.2 bar
Street and track use 1-2 oil changes/year, currently running Gulf competition 5W-40.