Finishing resin is a low viscosity epoxy specially formulated for wetting fiberglass cloth. It should work pretty good as a fuel/oil proof paint. Be careful when heating uncured epoxy, especially a large amount of it. Heat accelerates the hardening of epoxy and epoxy gets hot on its own as it hardens. I have seen a couple of thermal runaways where the epoxy gets so hot that it starts to smoke and boil. Admittidly, this will not be a problem when you only mix a half ounce or so of it.