There are some specialty clears made to protect metal.
Have never used them personally, so I don't know how well they work.
Since most paints require an acid to promote adhesion.. I would think these clears might have a problem of peeling over a long period of time, especially if exposed to the California sun for a long time.
Just like any other paint........
If it's an acrylic base, adheres properly, and isn't lacquer based..... then I would think it'll protect against rust..
Definitely should be a two part clear, with epoxy based being preferred.
"Bye" Bye" Riceboy
(Ex-wife fore sale... take over payments)