REV-X Super Ultimate Kit for Diesel - 4oz High Performance Oil Additive (2) + 8oz Ultimate Fuel Treatment (2) Greatly Improves Starting In Cold Weather and Dissolves Stiction in Powerstroke Diesels. Increases Efficiency, Horsepower, Torque & Lubrication Service Life. REV X is safe for all Soft and Exotic Metals. Reduces Exhaust Emissions and Diesel Smoke. Cleans entire Fuel System and Oil System. Ultimate goes in the fuel tank and Oil Additive Goes in your Engine.