KD, interesting question and I can give you my experience as I still have a 2013 5.0 XLT. Close to 110,000 miles and burns no oil. It has been a great truck, that is why I kept it instead of trading it in. Anyway, towing my 5,500 pound camper I am down at about 9.5. Around town it is 15 and highways 19. Not great numbers.
Good to hear as I just procured a 2019 5.0 F150 4x4 for my friend today. He likes it so far.
2018 Ford F-150 King Ranch 3.0L Power Stroke 4x4 | Icon 2.5 Front & 2.0 Rear, Toyo AT II 295/60R20, 3" ProComp Rear Block, S&B Dry CAI, LineX & BakFlip MX4, BuiltRight Seat Release | ForScan Mods: Disable Double Honk, 2x Panic, DPF Full %, Digital Temps Above Gauges, A.S.S Disabled | HP Tuners/nGauge, EzLynk, Ford VCM II, OBDLink MX+