Toddman0025

Looking for something that will clean the 40yrs of black gunk on the underside of my hood, but not damage the paint.

Simple Green?

Starfury

As good as any.

Toddman0025

Should I dilute to preserve paint or no worries?

Starfury

IMO, Simple Green is pretty mild. If you were using SuperClean, I'd worry. That said, 1:1 with hot water should probably do the trick, and the hot water should help penetration. If not, use it straight.

HGC

I used Fantastic spray cleaner on mine.

Iskwezm

Unless your using a pressure washer, you probably wont get much by off hand if its really thick

2+2GT

I'd start this job with a pressure washer. If you don't have one, go to a self-serve car wash. Make sure you take along what you'll need to dry out the inside of the distributor cap, so you'll be able to go home.

67t5ponycoupe

Simple green and a scrub brush got the underside of my car looking like this.

Toddman0025

WOW nice results!