Frame prep

The Rust-Oleum brush-on gets my vote. Its inexpensive, easy to touch up, minimal prepwork, looks good, and it will last as long as anything else. I've used POR-15 and it's a good product, but only on surface rust. If you apply it over previously painted surfaces or clean metal, it won't stick for sh*t. I've used SEM Rust Trap and it sticks well to bare metal and painted surfaces, but it's around $45 a quart, and its very thin and doesn't cover well. IMO it doesn't seem to have any real advantage over Rustoleum. The Rustoleum underneath my Regal still looks like the day I put it on, although it doesn't have a lot of miles on it.

Unless you get the frame dipped, which is something I haven't heard of anyone doing up until this point, you are still going to get rust bleed from seams. My boss's truck frame was blasted and powder coated a few years back and its starting to peel and rust in spots, and it hasn't even been out of the garage since it was done.

After cleaning frame to bare metal then priming, I used Rust-oleum Hammered finish Black which looks grey, once it fully dried (about a month later) it is very hard and durable, for something that came out of a rustoleum can I was surprised.

I hate to be the only guy knocking Rust-Oleum but Im not impressed with it at all. I have a friend that used the hammer tone grey on his car trailer and it looks like crap after two years of being out in the weather. I think once the VOC laws came into play and all the good stuff was taken out of enamel paint none of the stuff out there really holds up that long.
I had my landscape trailer blasted to bare metal a few years ago. My neighbor does it in his shop. I wanted him to shoot it with an epoxy primer and spray it with a good automotive acrylic enamel. He told me not to waste the money and just do it in a good implement paint. I took his advice and bought Valspar enamel. Used their primer too.Worst thing I ever did. Looks like crap and its only been a few years. Looked great for the first year.
Ive had real good luck with SEM Hot Rod Black. Its the right semi gloss. 2K paint. Flows out nice. Matches every time you spray a part. Its not as cheap as a regular enamel but it seems to be a real quality product. A guy I know that owns a shop was so impressed with it he now uses all the time on frames and suspension parts.
I turned him on to the SEM and he turned me on to U Pol Raptor bed liner. Another great product ! Great for the bottom of your body !!

I totally agree with being out in the weather, extreme temp changes, constant sun, rain, use something better suited for that (my primer is a 2k epoxy primer). I do liked the hammered look and my cutlass only lives in good weather (my garage). If it didn't I would have gone a different route...

I had mine blasted, before notch, reweld, and boxing. Then epoxy prime, and Eastwood ceramic chassis black. I also used the internal frame coating.