In one of you previous posts you mentioned how you like to rev your expensive engines when cold, you being unwilling to let them warm up first."Goes to prove that lower-viscosity oils do nothing to prevent startup wear nor does it show that this operating region is the source of most wear. Of course there is "cold start" wear but it is not mitigated nor reduced by low-viscosity oils. That's the goofy postulate we hear on here many times."
That depends. For some reason there are cars that limit RPM until the engine oil gets up to temperature. There must be a reason for this.
Personally I pay less attention to 100C and HTHS viscosities. I am most concerned with the 40C viscosity. I want it as low as possible so I feel comfortable running up the RPM in the cold engine (room temperatures here in Florida). I like high RPM and when engines are cool they go into bypass too soon. I have more on that one -but for another day...
Ali
Scott