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

I change my mobil1 usually at ~3500 miles, but may push it a little further this time since all the old gunk should be well out by now (didn't get to start using mobil1 till about ~81k miles and have about 94k miles now) and that I may be a little strapped for cash for a little while as far as car maintenance goes. When I drain it, it always looks like the day I put it in, so I'm not worried, but just hope the motorcraft filter is up to it.