Frigid Fix diesel fuel anti-gel and additive is specially formulated to work on both diesel-fired heaters and engines. Keep your heaters and diesel engines running at peak performance all winter long, even in frigid temperatures. Use on diesel fired radiant and forced air heaters, diesel trucks, cars, tractors, and other diesel engines. Simply add at least 1 ounce to every 5 gallons of fuel for optimal performance. Made in the USA.