10w60 is too thick, a w50 is about as high as you want to go in a standard or slightly modified car, on a full rebuild 500bhp+ monster, yes run a w60 as your temps get it to a nice runny mixture, a w60 is about 50% thicker than a w40 at 100 deg, thats alot of drag on your engine and the oil pump has to work harder.
Tony
