Tim,
If it is very oxidized there are really only 2 choices for improvement. 1) Paint. 2) A labour intensive project of cutting (if bad enough may need "wet sanding" as a last resort), followed by polishing, followed by the application of a good wax.
#2 requires the use of a good polisher and hours of time.
If you are interested in #2, PM me with your email address and I will send you a copy of an article I got from Rod Collins of marinehowto.com, but I could not find the article on his site today.