buy a bottle of 3M perfect-it 3000 (if it is really bad, use extra cut instead of perfect-it) and if you have a buffer, a nice foam pad. Use that to buff it out, there is no set time for it. It can be done by hand if you have no buffer but it will turn out better with an electric buffer. Use a nice polishing wax on it afterwards, rub it on, let it dry for a few minutes and wipe it off with a clean towel. I haven't had to do this to any of my cars but I work on yachts and we do this to gel coat and paint all the time, it will take out some of the worst oxidation and some light scratches. if you have deep scratches that aren't through the clear coat, take a small felt sanding block and some 1500 grit paper and wet sand them out.
