I have been using Tractor enamel...its cheap and durable. I used a semi gloss. Never use a flat paint because it cannot be washed clean. And always buy tractor paint with HARDENER. Dries enough to handle in 4 hours. If you do not use hardener....it will be several days before you can touch it. The stuff I used was Valspar from Fleet farm, and now I used the cheap Old 55 (they stopped carrying Valspar), expect to pay $30-$50 for a gallon and $10-15 for reducer and $10-$20 for hardener. This paint is also impressively resistant to Brake fluid, which will eat off rattle can in less than a minute. I have let Brake fluid sit overnight....unintentionally and wiped it off and it just dulled the paint...never removed it. A gallon will do a whole chassis, underbody, fender liners, firewall and core support....and also the bottom of a hood. Not too bad for $75-$100.