I posted about this on the Detailing 101 board, but I thought I'd mention it here also. I had a badly oxidized gel coat motorhome. I bought and tried M67, M44 and M50, with poor results. I read about folks with boats using Bon Ami Original 1886 Formula Cleaner (not the Cleanser), to clean the oxidation off. Thought I had nothing left to lose, so I popped the $2.19 a can for some at my local True Value Hardware. Using wet terry cloths, with Bon Ami made into a paste with water, I went over all the fiberglass by hand, rinsing as I went. It removed almost all the oxidation, leaving a very slick surface! Then the next day, I went back at a section with a PC and #50 Marine Cleaner Wax, and it came out great!! The M50 took what was left of the oxidation off, and restored the gel coat to a beautiful shine, probably better than new!!

My theory is, the loose oxidation was gunking up the pads so bad, that the products I tried couldn't do their job. After I got the surface prepped and clean with the Bon Ami, the #50 went on like a dream, and polished the fiberglass like........ well, like glass! I had tried using other cleaning products to get the oxidation off, including some pretty aggresive stuff, and nothing worked like that two dollar can of Bon Ami.

YMMV, but it worked for me. I took some pics that I'll try and post here and in the other thread later.

Once again Meguiars came through, with a little help from another old American product!!