Quickleen Engine and Fuel System Cleaner 8M0047921 is for use in all 2‑ and 4‑cycle carbureted and fuel‑injected gasoline engines. Safe for catalyzed engines. It can help maximize engine performance with all grades of gasoline. It will help control corrosion, gum and varnish build-up and phase separation associated with ethanol blended gasoline. It will quickly and thoroughly remove carbon deposits from carburetors, injectors, intake valves, spark plugs, piston crowns and cylinder heads. It can extend spark plug life and prevent engine knocking and piston seize-up.