[skylinergtr]

^^

on a car like a mazda rx-8 i would not use 5w-20 with it's high rev's. However, on say normal cars or trucks its fine. My 2002 Ford Explorer V8 has been using conventional 5w-20 since it was new. It doesn't leak or burn a drop. I've driven the piss out of it before. It runs absolutely great. Normal daily commuter 'no fun cars', 5w-20 viscosity should be fine, rev happy sport cars... look at heavier weights.