I have seen pretty effective results using zinc-chromate primer, although intended for non-ferous aluminium, it seems to protect steel very well too.
Recently, I saw this stuff, "Rust-Oleum" Professional, cold galvanizing compound, zinc-rich coating, at Home Depot. It is in a spray can, the heaviest spray can I have ever felt!
I plan to try it on my rust bucket, 450 SL, and see if it will do better than paint, epoxy, or whatever.
I agree too that oil seems to be a very effective barrier for steel and a good way to go for sure.
BB