I have run Mobil 1 ATF for the past 45,000 miles without a problem. Smooth shifts, etc. But, reading the various posts regarding what fluid (ATF, motor oil, manual fluid) to run through the SVT gearbox, I decided to find out for myself what the manufacturer specifies (and yes, I know the 2004 SVT manual is contradictory).
I called the Ford Performance Group (what used to be Ford SVT) and asked, explaining that the manual states both manual fluid and ATF. The reply was that the SVT 6-speed Getrag tranny is NOT the same as the MTX-75 and yes, it does call for Mercon V fluid - which IS ATF. With that, I'm sticking with what I'm using (although the Royal Purple ATF is tempting, but is it worth an extra $3 per quart?