Read thread here on RCU on engine cleaning. Follow Dawn PD mfr directions. Close off all openings of engine. Spray Dawn PD liberally on affected areas. Let stand no more than 30 minutes (engine caastings may turn darker grey if left longer) Scrub with stiff toothbrush (don't brush teeth with this one again). Rinse off with hot water. Dry thoroughly inside and out with hot air blower. Rinse with alcohol. Lube liberally with afterrun oil or Marvel Mystery Air Tool Oil or ATF, turning engine over by hand to insure oil gets everywhere in engine, including bearings. As always no intended or expressed warranty for suitablility of this methed for your application is expressed. Good luck