Tried it many years ago. It didn't hurt anything but I don't recall that the product (probably turtle wax) held up well to glow fuel residue. On an electric or a large gas model that stays relatively clean it might be worth the effort. On the down side it might interfere with repairs. I know from painting full size cars that a wax remover is required to prep the surface before any attempt to repaint. I would bet that new monokote doesn't adhere well to a waxed surface.