JJS wrote:

tried it under the belly and to make a long story short, I spent the
next 15 minutes on my back with a rag, and 8437R's tummy never shined

so bright since her last new paint job years ago. It really works
great on belly grease and grime and fuel stains. It took me perhaps
1/5th of the bottle to do 37R's belly. I'll buy more when I've used
it up because it made the nasty job really go quickly. Aircraft
Spruce has it for $10. It meets Boeing spec D6-1748P.

Home Depot has VM&P Naptha for about $9/gallon. Works great on a wad of
paper towels for degreasing the belly of airplanes. I've done mine
about 7 times and still have half the gallon left. Dries away clean and
shiny too and does not hurt the paint. Just keep in mind the
flammability and use in a well-ventilated area.