Which primer under Dolphin Grey?

[Bordfunker]

I'm just about to repaint part of my chassis following a suspension overhaul, and have already primed it with a grey etch primer.

 

I was intending to give it a coat of red oxide primer before applying the top coat of Dolphin Grey, however I can't remember why I was convinced that I needed the red oxide base for the grey topcoat.

 

Is my memory playing tricks on me, or should be applying the top coat?

 

Karl