I have asked this before and thought it would be better for my engine, but it is the same as conventional. Synthetics are good for cold starts (below 32) and high temps. I read if you have a 140 thermostat, your engine oil is running cool also, so you get no benifits from synthetic. Possibly the only benifit is when you extend you changes, which i wouldn't recommend since convetional oil is about 1/4 the price of synthetic. Go for a good straight weight oil. Multi-grades as a 20w-50 are only a 20 weight oil with viscosity improver added to thicken the oil when it gets hot. These break down very quickly with high rpm's and could cause ring sticking and your oil will be a 20 weight. (too thin)