One last thing. If you go synthetic you are not supposed to put that crappy regular oil back in, but after you use synthetic you won't want to go back, your car will thank you. Also I would dispose of the myth that when you use synthetic you can go 4-5,000 before changing it. I never go over 3,000, sometimes when I have nothing to do I'll even change it at 2,500. Depending on how I've been driving it.