Amzoil and the appropriate filter. Their site has a cross reference list, but their tech line is extremely helpful also. I like their zero weight series so if your oil cap says 5w-30 you'd get 0-30, I run 0-20 in the focus, F250 and the 06. I run 0-30 in the 90. It's good for 15k with harsh driving which is how I consider all my driving. I change it in Oct before it gets cold and it lasts me until spring. I'll also change it more regularly in the truck if I'm trailoring the cars a lot. If you look at wear tests the brands you buy at the store really don't stack up against it. I've heard royal purple is good, but haven't seen any test results that would make me want to switch over.