Done the underside mainly with rustabond and red oxide where I couldn't guarantee it was degreased properly.
Bought rustoleum combi colour which although horrible to paint seems hard wearing. Problem was it was more Rosso Red than radiant but thought two coats of this will protect it and I can worry about the top colour later

Bought a sample of Synthetic Radiant red of ebay, hardly any smell, painted over anything and no adverse reactions. They sell it in packs with a grey oxide primer and it painted over rustabond, red oxide, the rustoleum and the original radiant red no problem.

Bought five litres of synthetic radiant red from the local paint shop, feckin xylene based, fumes would kill a horse and it reacts badly with everything.
Total p.i.t.a.

So is there a non xyelene based synthetic paint. Sample from ebay was described as oil based coach enamel.