I used Chassis saver, though I'm sure its the same as POR-15, Zero Rust, etc. Its about 50 bucks a quart, but it seems to stick really well. I've used POR too, but there is a bit more prep work with it. It does dry tough as nails though. I did a mower deck with it, and had to retap my threaded holes to get the bolts to start.
The chassis saver was easy to apply. Get the scale and loose stuff off, clean it. Clean it again, seriously. CLEAN. Brush it on, and let it dry. I used some thinner/reducer which helped level the brush marks out. Once its dry, I scuffed the gloss with a scotchbrite pad (red) and hit it with the semi-gloss Krylon, just to knock the edge off. Chassis saver is VERY glossy.
The chassis saver was easy to apply. Get the scale and loose stuff off, clean it. Clean it again, seriously. CLEAN. Brush it on, and let it dry. I used some thinner/reducer which helped level the brush marks out. Once its dry, I scuffed the gloss with a scotchbrite pad (red) and hit it with the semi-gloss Krylon, just to knock the edge off. Chassis saver is VERY glossy.