Liquid Performance Diesel Doctor Complete Fuel System Treatment is your one step fix to all Diesel Fuel problems. Its full synthetic formula contains no alcohol, increases cetane, prevents water build up, prevents gelling to -40°, prevents algae growth and reduces smoking. Diesel Doctor increases horsepower and fuel mileage. This product is EPA Registered. Add 1 oz of Diesel Doctor Complete Fuel Treatment to every 10 gallons of diesel fuel.