Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance How long does synthetic oil last?

You don't HAVE to change mobil1 at 3k miles either. Where is the proof saying that mobil1 can't do the same intervals as amsoil? Changing the oil really isn't a hassle, finding oil at a good price is. I can't get amsoil locally, and it costs a bit more than mobil1, then add shipping. And it cost more and was more of a hassle to get.