Since the first oil change I've personally ran Rotella T6 5w 40 on my 2011! Truck only has 60k on it but haven't had a lick of problems!My coworker has the an 11 as well with 100k on it and runs T6 and hasn't had any problems so you might look into that.
I'm usually averaging 15-16mpg running on 35s with Spartan tunes....I pull a 20 foot skeeter around everywhere and average about 14.5mpg and that's being somewhat nice to it!!
11 KR F250 4" Ranch Suspension lift with Rancho stabilizer kit(4.5 front 3 in back)...Bilstein Shocks...35x12.5 Cooper Discoverer ATTS...18x10 Mayhem Chaos! Sorry about the bad picture I can get more later