Diesel Fuel Supplement +Cetane Boost is a winterizer/anti-gel that is used in the cold winter months to prevent fuel gelling and keep fuel-filters from plugging with ice and wax. When temperatures drop, paraffin (wax) in ULSD fuel will gel stopping fuel from flowing through the engine, and water in the fuel can freeze on the facings of fuel-filters, blocking fuel flow. Contains Slickdiesel Lubricator to protect fuel pumps and injectors from increased wear caused by poor quality Ultra Low Sulfur Diesel (ULSD) fuel. Effective in all diesel fuels, including ULSD and biodiesel blends. Diesel Fuel Supplement +Cetane Boost is intended for use only during cold winter months when temperatures drop below +30F. Use Diesel Kleen +Cetane Boost (in the silver bottle) for peak performance in non-winter months. Treats up to 40 Gallons.