I used ORANGE 409 household cleaner. Sprayed it on the engine when cool, let it soak a few minutes, then hosed it off. The engine came out very clean, with no pitting of metal surfaces. I blew the water out of the intake bolt holes with a can of computer air duster and wiped black rubber parts with a cloth. Looked almost like new! Also did my 2001 Intrepid the same way. Same results. Highly recommended.