This Combustion Chamber Cleaner cleans carburetors, intake manifolds, intake and exhaust valves, pistons and combustion chambers. Removes deposits, eliminates carbon knock and restores performance. Prevents fuel system varnish. Also prevents heavy carbon deposits inside the combustion chamber, a this cleaning product may be added to the engine to soak for 15-20 minutes to loosen the deposits. An oil change afterward is recommended because some of the cleaner will end up in the crankcase.