Best engine/trans cleaner??
 

I have purple degreaser but, it is dangerous on paint. Want to clean underside of engine and trans but, can't run the risk of getting any on paint. Ask me how I know. I have a lift and pressure washer. What is out there that will get old, heavy caked-on grime off and not harm paint?
Thanks,

I use spray on Simple Green. Spray it on your engine then agitate with a one inch paint brush with the bristles cut a little short to make them stiffer. I rinse with a small watering can instead of a hose so it doesn't make a big mess. Works great.

Your engine is made of alloy. That is why it is coated with a brown wax. And everything made of alloy else is also coated with that wax, because alloy corrodes. If you remove the wax the alloy will corrode.

Regards, Markus

Spray bottle with undiluted Simple Green, and another sprayer with water. Works for me. :)

What I did
 

Waited until the engine was stone cold in the middle of a summer day. Sprayed a mild soapy solution to break up dirt and dust.....finished with pressure washer but I never pulled the trigger.....jut the little soft spray. I avoided wiring as much as possible and let dry for 4 hour before starting car up. Harsh cleaners like the purple one are very aggressive and can shorten the lives of seals and other things....use carefully.

Thanks guys, I really want to get the grime and the grease off the bottom of the transmission and the motor - not so much on the top. It's. Caked up pretty bad from POs who did not fix leaks. And now just replaced the AOS which sprung a leak. I didn't realize that I might remove the special coating.

X3 for simple green

Thanks WOODY and thanks guys, I think I will be using simple and a garden hose first. Woody, SpecboxCO never got back to me on the cup holders.
Woody, got a good lower AOS vent hose? Clip on mine broke and I did not think I can engineer a temp fix. Plus, the intake duct for my 02 S has as separation on the hose for the resonator. I will try to silicone it but, it may not hold.

Another thought: would not a few rags and elbow grease do the trick? It would seem worth a go.