STP Super Concentrated Fuel Injector Cleaner contains concentrated detergents that help dissolve and remove harmful carbon, gum, and varnish deposits on fuel injectors. Without cleaning, deposits can lead to hard starts, lost acceleration and rough idling. This product is made with jet fuel, a high-quality carrier of active ingredients. This product is compatible with cap-less gas systems. 5.25 fluid ounces bottle treats up to 21 gallons of gasoline. For over 60 years, and for more miles than anyone can count, STP has been one of the most trusted names in automotive care. Car enthusiasts, “Do-it-Yourselfers” and professional racers rely on STP oil additives, fuel additives and brake and power steering fluids to keep their vehicles running better longer. And they count on STP automotive appearance products to keep their vehicles looking great, too.