I should be asking the same question. I have used charcoal lighter fluid to clean most everything oily or greasy. The charcoal lighter fluid does not seem to attack plastic or rubber and is fairly safe to use. I have sprayed or brushed and used a paint brush to loosen tuff stuff on my wheels and motor and washed it off with a power washer and it seemed ok. My power washer is a small electric unit without a lot of pressure, 1200 psi or so. Beware, do not contaminate your brake pads, ask me how I know. Some say Simple Green is good but I have not had good results with it.