I had to paint some parts I made out of aluminum and got a zinc primer and top coat in spray cans from an auto paint place. I also used a clear coat for protection but you wouldn't need to. The key is to use the right primer on aluminum and the paint store had it on the shelf. The cans were much more expensive than Rust Oleum but have held up for almost three years now and still look new.
SV Laurie Anne
1988 Brewer 40 Pilothouse