Is there such a thing as *special additives* designed for a particular brand of a car. Just browswing some bme messageboards and alot always say *Just use the OEM BMW oil since it has special additives that are tuned for car. I know that the BMW Castrol is synthetic can could these additives somehow be better for my car than other oil that I am using and others I'm planning to try (Redline 5W30, GC, Amsoil 2K and also the Mobil SUV).