what i ment by 100% synthetic is that everything (oil and additives) is made in their factory, all other companies that claim to be full synthetic still has some petrolium in it. im friends with one of the head mechanics at a local chrysler dealership, and he said when they get a car in with the 2.7 liter (the ***** motor with the small oil galleries that always sludge up) no one wants to work on it because they dont want to clean that ***** out, but he said he noticed that people who used amsoil and penzoil synthetic had a lot cleaner motors then the others.