I have a 2000 F-250 SD 5.4 with 107,000 gentle miles. I switched to Mobil 1 5W30 awhile ago and have noticed that I'm using 1 to 2 quarts between oil changes (5000 to 7000 miles.) No smoke, no leaks, no power loss. My son says this is a common gripe with the M1 oil. Any experience out there?

 

Yes I agree.

I'd go back to the motorcraft 5w20 or 5w30.

 

I have read in the past that full synthetics can have problems with old rubber seals such as the rear main seal that have become less pliable over the years. Apparently dino oil helps to keep rubber seals softer.
The solution seems to be to go back to what you were using before although I have a 99 5.4L with 105,000 miles and no oil burning issues with synthetics.