I was told the same thing by Ford Performance- that the factory fill oil is the Motorcraft 5w-20 synthetic blend. I'm going to do a break-in oil change with it at 1000 miles (I'm at 450 now) then change to Mobil 1 EP, which I will change once a year or every 5k miles, whichever comes first.
Same here, as I figure you cannot go wrong with eiter the M1, or Castrol
EP synthetics (unless maybe one has a stupid big power, BT setup, then I'd look into the much more stout, but NOT Ford spec/warranty friendly, 'boutique' synthetics, i.e.; Motul 300V, Red Line, Millers NT, etc., and then the warranty does not matter anyway, since you tore it up with the BT kit install).
Except that ('waste' or not) I will change it twice a year, regardless of mileage (because hot running, D.I. turbo, you know).
I am even thinking of going to a 0W/5W-
30 for the late spring, summer, and early fall OCI.