I had a mix of some light skims of bondo, some bare metal, some scuffed paint, and chrome.

Some of it I spraybomed with Rustoleum/Tremclad primer, some of it I mixed and sprayed with straight Tremclad primer (=the stuff you'd roll), and yet other areas I spraybombed with Duplicolor Primer. Generally I used more Rustoleum than Duplicolor, and all the bonodo was covered by Rustoleum, and it didn't sink in. That said, the bondo was no more than a skim in any of the areas, so there wasn't much to sink into...

Anyway, some of it was White primer, most was grey, and bit was even black (I should say that I did the bodywork over a period of time, and the patchwork of primers was simply because I wanted some paint on the thing to save it from being in bare metal). None of it was Primer/Surfacer.

Anyway, when I came to paint the car - using Rustoleum/Tremclad, the paintjob itself kind of spread from 'I'll just do a test patch' to 'I might as well keep going', and consequently, I went over the whole mess of different surfaces, totally forgetting that I 'should' have used a surfacer.

But - I had no adhesion problems, no flaking, nothing.

The only thing I can say is that each and every bit of primer was totally cured (at least 20 days) before I painted the thing, which probably helped.