I sprayed this one with Rustoleum on the cab and bed and used Kirker ultra-glo acrylic urethane single stage on the fenders..
No oil base or synthetic-alkyd enamel will hold up well or keep its gloss if used without a hardener or activator. I used the same Kirker ultra-glo urethane activator with the Rustoleum that I used with the Kirker paint on the fenders. The Rustoleum-Kirker combination worked well and saved lots of money. Kirker sells one of the lowest priced single stage urethanes that I know of. I painted my speedster with Kirker acrylic enamel with hardener in 1995 and it still retains its shine .
Dodge makes a good point about Rustoleum and patina if left outside. If no type hardener or activator is used it will fade quickly, even quicker if thinned with lacquer thinner or acetone.
I plan to use Rustolem without hardener, thinned with lacquer thinner on my 29 tudor. I want the patina look. If used in this manner it will have good gloss at first but will fade quickly. Purdy.