I went from Valvoline 20w-50 full syn to Kendall straight 50 SAE racing
oil. It stablized my
oil pressures (more narrow band when hot...higher at idle and not too high under stress) and also lowered my peak
oil temps. I really love Valvoline products, but had to make a change when my bearings started to go south prematurely. I thought about experimenting with a Valvoline 10w-40 (I think the 30w for my particular engine clearances would be too thin), but swapping out 8 qts w/filter gets expensive if you do it too much.
Oil selection is a real science.
-Dean #747