I was wondering if 0W30 oil would be safe for a WRX or STI boxer four. I am interested in Amsoil products but their application chart says that 0W30 of their racing oil was recommended for the STI, which is not the owners manual spec of 5W30. Will a hard working turbo boxer running laps on a hot day running 0W30 oil cause engine damage? Will the polymers responsible for multigrade oil really be thinner at temperature? Right now I'm leaning towards the Amsoil XL 5W30 (non racing) because it fits the oil grade requirement for the vehicle. I've been googling and from what I've read redline mobile-1 and amsoil use equivalant high grade synthetic base stocks. Would any one be able to shed more light on this?
if i'm thinking right, the cars running hot laps for a while needs think oil.. cause when the car is hot then the oil is burning and getting heated on very high temp's which is thining the oil.. u need somekind of thick oil, racing ummm 5w30 is rec, but for racing apps, i would try to get expert's advice.
After educating myself that the W in multi-viscosity oils is for "W"inter, It appears that running with a lower cold weight just means that the 0W oil exceeds the requirements for cold-start ability of a 5W oil.