The Prolong Super Lubricants Commercial Grade Diesel Fuel Treatment, formulated with premium detergents, removes gum, deposits and sludge buildup from injectors and the entire fuel system. The result is improved fuel economy, less black smoke and better performance in heavy duty diesel work trucks and commercial vans, according to the company. Pouring 1 oz to 2 oz into the vehicle's fuel tank before fueling treats 10 gallons of diesel fuel.