Tenderloin- I have been using motorcraft 5w-20 and so far all the reports have been good. My truck doesn't burn any oil, the oil has been through a lot (very cold temps and some heavy towing). I change around 3000 miles and have yet to see any problems.
Jay- Don't know if there is a user named msparks but was wondering if you mean mscales. If there is a msparks I would like to know so I can take a look at his reports. I was also wondering where you were able to find M1 0w-20. I have been looking and am very interested in giving it a try in my truck. I think I have enough of a baseline on the motorcraft to catch any problems with the M1.
Thanks