Which grade of gas to use when towing

I've heard that when towing, use super-unleaded gas.
Better gas mileage and engine will run cooler. That's the theory anyway.

Plan on moving my daughter to Mississippi next w/e, pulling a 5x8 enclosed u-haul trailer with a 2004 Expedition (5.4L, 2WD).

Does using super-unleaded make any difference?
I know it will cost more but will it be better/worse for the engine and MPG?
Thanks in advance for your thoughts.

Put one tank of each in on your trip to see witch one you go longer with

Well, started out with a tank full of regular. Drove about 330 miles. Filled up with premium and drove another 300 miles. Didn't see any appreciable difference in MPG.

Octane is fuels ability to resist detonation using a higher Octane than what ur car is rated for does nothing for you