There's a late 90s Trek 5200 for sale locally. The current owner used automative paint to cover the original paint job, which is chipping away and revealing whats underneath. Can I sand the frame down, removing both the automative paint and the original paint, before painting it myself? My ideal end is to have a single color design, something nondescript. Perhaps removing the original is not necessary, but maybe unavoidable if the automative paint is to be removed too.