Oil
I use to use Amsoil in our race car love the stuff, but are there not to may other additives in it also. I saw someone mentioned Castrol and said it was a full synthetic, I did some research a few years ago on oil, (I was thinking of being an Amsoil rep) and found that Costrol in not 100% synthetic. A few years back Mobile took them to court because they are only about 80% synthetic and mobile tried to sue them so they could not clam full synthetic. Well the courts sided with castrile say as long as it is over a certain percent they could clam full. Since then Mobil has gone from 3rd to about 4th. Amsoil and Royal purple are top dogs. I also have some input on oil filters. One engineer I worked with did a school study on oil filters and found Frame to be the poorest in quality the internal elements are glued and easily come apart.