In case anyone asks about my recommendation.
I've used both POR15 and ZeroRust. I like ZeroRust. Using a paint gun, the texture, look, and feel are nice on metal. I coated my entire engine bay with it.
Read about it here:
http://zero-rust.com/
I bought mine from
http://www.restorick.com/zerorust.htm
I have pictures here: