Using premium gasoline in a Ford F250 V10 does not improve gas mileage but it may make it worse. The manufacturer's recommended fuel for this vehicle is regular unleaded gasoline.
The prevailing myth that premium gasoline provides better gas mileage is not true, according to Consumer Reports. The higher octane rating of premium refers to the fuel's ability to prevent preignition in the engine. Preignition does not affect fuel economy but causes the engine to knock. With sports car and other high-performance engines, the fuel burns hotter and provides more power. In engines designed for regular unleaded fuel, it adds to the cost of operating the vehicle.
To increase the octane rating of mid-grade and premium gasoline, manufactures blend ethanol with the gasoline. Ethanol contains less energy than regular gasoline and reduces the fuel economy of the vehicle. Switching to a higher grade than the manufacturer's recommendation does not bring additional economy to the engine. While premium gasoline includes additional detergents, these are usually not necessary, and a gasoline additive does a better job than burning premium.
Using fuel from a name brand station does not affect the vehicle's mileage when compared to an unbranded station. Most of the time, these small stations buy their fuel from the same source as the larger stations.