I have a couple of questions that you guys can probably answer. What kind of oil are you all using? I know the book calls for 5W30, but what about synthetics? I got a brother in law who is also a car guy (he has a WRX), who swears by synthetics. What's involved with switching over? Is it worth it? What about filters? I've been going to the dealership, and buying Motorcraft oil filters. Anything out there that's better? I tend to think about this stuff when I'm at 4000rpm.