Cavity Wax?

....Eastwood "internal frame coating" (green)....
Lol, I tried that stuff on my truck out in the driveway. Sure glad I put a tarp under it. I would have had a lot of green exorcist pea soup puddles to clean up.
To get further into areas, I taped the nozzle and tubing onto a straightened heavy wire coat hanger with a bend so I could twist it around.