Thanks for all the helpful comments. I think I'm convinced to keep the aluminum radiator as it's working well but I like Carl's idea of painting the top tank. I imagine that you sprayed those tanks before you installed them, Carl, so I'll need to pull this one - but it saves me several hundred bucks & seems like a good compromise.
I scuffed what I needed to paint (the top tank and the sides) with a red Scotchbrite pad, used self etching primer, and black paint, all Rustoleum rattle can products. I did not paint the fins since there is no way to prep that for paint, and I did not want to interfere with air contact with the core.
Carl
