Originally Posted By: AndySantoro
I am trying to u get stand an earlier posters comment about seeing cooler oil temps with RL. If I understand how the system works, the oil thermostat will regulate the oil temp. Regardless of some better oil brand thermal charecteristics, the engine oil temp will remain the same at normal operating temp. Maybe if you exceed the thermal capacity of the system, a given oil will run cooler, but I don't think that's what the OP was referring to. D
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Yeah, I've heard that RL oils "run cooler", which I can't get from a physics perspective, unless it's a lower HTHS oil than the type being compared to and generates less viscous drag.
I don't spend too much time worrying about the claim, as it's never been defended with any sort of data.
It's also claimed that PAO runs cooler because of it's specific heat..bu that's per Kg, while sumps are filled by volume, which is only a couple of percent difference in heat capacity per quart...in that regard a pure ester oil MAY have less temperature rise...but if it does, then there's LESS heat transfer to ambient, as convective heat transfer needs Delta T to drive the heat out.