I used protec 408. Two pack and is excellent. Not as nasty as the best products eg strontiom chromate from ppg but I was not prepared to use nasty chemicals. Degrease scourer pad metho and spray. It's a perfect base for single stage two pack for your top coat. Ferrours and non ferrous But only prime when you ready to paint. You can do a wet on wet for even better results. Remember once the primer is about 36 hrs old it's no longer primer and should not have a top coat on it.
Lyndon