Motul Engine Clean Cleans the engine before and oil change, can be used in all types of 4 stroke engines with injection or carburetors, with or without catalytic converters, using all kinds of fuel. Keeps oil clean longer and restores engine compression. Just add engine clean to a warm motorcycle engine prior to oil change. Let motorcycle idle for 15 minutes, then change oil and filter. Repeat every other oil change for prolonged oil life and clean running engine.