I see that 5w-20 oil is recommended, primarily for fuel economy/performance reasons. Less viscous oil makes it easier for engine parts to move around, makes sense. But I also know that thinner oil protects less than thicker oil. Im thinking of going the synthetic route if Im going to keep using 5w-20, otherwise Im going to move to at least 5w-30. Synthetic oil does do a better job of protecting, right?