This is an old thread, but somebody will benefit from this post.

I rarely recommend a product but when I tried this one, I couldn't believe my eyes. And I have no connection with the company except as a loyal customer.

It's a cleaner made for removing brake dust etc. from wheels, and it works just as awesome inside the engine well also. Just spray it on, wait a minute or two, and hose it off. It doesn't harm paint, plastic, or rubber, is non-acidic, isn't toxic.

It's from a company in Largo Florida, and it's called

Brown Royal
Wheel Cleaners and Polishes
flash wax. com/ wheelcleanerpolishers.h tml (just remove the spaces)
727 582-9073

Search youtube for 'Brown Royal Wheel Cleaner'.

Buy it online by the gallon, get a one dollar spray bottle from Home Depot, and you'll be amazed. I am.