[David70]

Personally I would just use a regular hose and some type of mild detergent (Simple Green or other) and a wet rag and avoid the high pressure. The time savings/benefit for the pressure washer isn't worth the possible problems to me.

Many years ago I worked at a Nissan dealership detailing cars (high school and college) and we almost always pressure washed the used car engines and then clear coated them. Virtually never had a problem I just don't have that much dirt to deal with that I can't just wash/scrub it off.