Warren Distribution Super Concentrated STP Fuel Injector Cleaner , 5.25 Ounce -- 12 per case. 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. Helps Restore lost power and acceleration Smooth rough idle and eliminate tough starts Save gas by cleaning fuel injectors, restoring lost fuel efficiency Usage Frequency Use every oil change or 4,000 miles.