Looking for best way to get 50 years of oil and dust (cake) off engine and tranny. Don't really want to pull them out to do this. Engine has been seeping oil and here in Tucson we get alot of dust. So now I have this really nice rust barrier that is pretty tough to clean off!! Should I use Gunk after warming up motor and let it soak in or use Purple Power? I recently used this Purple Power and it cuts grease but must scrub to get it off. I would like to blast off the crud at the power washer.