I used Herculiner on my wheel wells and is has done a remarkable job. I am contemplating painting the whole trailer with it. Just grind off all of the rust, treat it with a rust converter, which you can buy at Wal-Mart in the automotive paint department and roll the hurculiner on with a 3 or 4 inch roller. It was pretty easy and the ther results have been great! The only downside is that it fades. They have a product that is supposed to stop the fading, but I haven't used it. Good luck!