Epoxy Primers when used on metal are for corrosion protection and helping with adhesion. It is a NON-SANDING Primer! The Correct Name Should be "EPOXY SEALER", because that's all it is! This product is a sealer to use on different surfaces for protection from foreign elements to eliminate contamination!
Some advantages of Epoxy over Self-Etch:
Epoxy is very friendly (user friendly) and is very compatible with other products. You don't have to worry about anything lifting like you might with a Self-Etch primer. With epoxy, you can lay it over just about anything, body work, sanded paint, metal and you're going to be fine. With Self-Etch, if put it over different layers of paint, if put on too wet, it's going to lift because Self-Etching primer has acid in it. Be aware of this. Epoxy can be more expensive, but then again….when you are already spending hard earned money on restoring the car of your dreams, a few extra bucks isn't going to break the bank.