I switched back to Amsoil because I was told that synthetic are better on engine seals.Engine seals with dino oil will dry out I was told.Also I am to understand that dino oil will leave more depoits and sludge inside your engine.My question is can synthetic be worth the extra money?I have 91,000 miles on my 2000 Powerstroke and I with Amsoil change the filter every 10,000 miles and both filter and oil at every 20,000 miles.Should I go back to changiung both every 5,000 miles?At every 5,000 miles I know nothing but fresh oil will be in the truck
.Thanks Joe