The STP Fuel Injector & Carburetor Treatment is specially formulated to keep your engine running smoother by tackling the tough buildup that targets injectors and carburetors. With consistent use, it helps prevent hard starts, lost acceleration and rough idling by fighting harmful deposits and reducing friction within the fuel system. It’s safe for all gasoline engines — even those with newer cap-less systems — and is designed to maintain optimal engine efficiency and fuel economy. Simply pour the treatment into your fuel tank before or after refueling and use it regularly to help keep your fuel system clean and your engine performing at its best.