Pickup trucks can definitely be expensive to fill due to its huge tank compared to the smaller vehicles. We have a truck that is used for the small business. We've recently installed Fass fuel pump to the truck which transfers the fuel from the tank, up to the engine’s injection system. You can improve the gas mileage by1 to 2% by using the recommended grade of motor oil by your vehicle manufacturer. For example, using 10W-30 motor oil in an engine designed to use 5W-30 can lower your gas mileage up to 2%. The thicker the oil, the harder it will be for the pump. This adds to parasitic horsepower loses.