I have run Mobil 1 for several years now with great results - including picking up at least a MPG in my 5.4 '01 F150. My 'new' '06 6.8 V10 has 7 quarts of what the dealer installed as part of his pre-delivery, and is Motorcraft 5w-20. I'll probably change to Mobil 1 10W-30 in a week or so and of course check the gas mileage - this beast needs all the help it can get. The Mobil 1 goes in clean and 5000 miles later still is very clear The '01 used no oil between changes and my wife's Escape is the same. I did try Castrol Syn-tech 2 times back to back on the '01 - and it went thru a quart every 1500 miles - then I did some decent research and came up with Mobil 1, Amsoil and Royal the best synthetic with Mobil 1 being the only one easily available locally - Wally World, K-Mart and Advance - and I do watch out for price specials.

In response to Denny's comment, Mobil 1 had major problems in the '70s when first introduced - it could sludge an engine to failure - and I, too, wouldn't use it for many years but since "Have Seen the Light"

And I use it in my air compressor - but do draw the line on the gas lawn mower. The diesel baby sized tractor - I may even do this one in the fall at its' next change