Mobil 1 is the best out there and it is only 4 dollars a quart. BMW, Mercedes, Aston Martin, Viper, several other exotic cars, spaceship, airplanes, and tons of small commercial use Mobil 1. I think a lot of 18-wheelers use Amsoil because it can take more abuse in a year than Mobil 1. Amsoil can only be bulk purchase from online and catelog vendors. They put so much zinc in it that it is bad for the catalyst. It is way over kill for smaller vehicles because zinc is a super overkill agent. It is bad for cars too.