Correct me if I'm wrong, but he asked for "best" not "cheapest".
My truck is also a driver, but I do not see that as a reason to do a substandard job on it. I do obviously have money constraints so I also used Rustoleum(in quarts). However for a tub of filler, some abrasive paper, and 30 hrs work I can have a
smooth shiny
frame, which is definitely worth it. And now I'm driving it around with a restored frame and rusty body as I am flat out of cash.
Honestly NOT trying to pick an argument but sometimes a more economical (and slower) way MAY be the best way. I'm not saying I would EVER paint over scale or rust using my part-at-a-time approach. On the contrary, I'd pressure wash the chunks off, clean the scale, loose rust and paint off with a wire wheel, then sand (not a DA air sander as is standard in all car magazine write ups = expensive compressor & accessories) with my regular cheapazz electric sander, all the paint to an acceptable finish before priming and painting. Maybe by brush if necessary but if using a good self-leveling oil based enamel like Rustoleum, how is this "cheap" or substandard? Its not like we're going to be laying on the ground admiring our frames daily. If you want to do that, then by all means, go nuts.
I'd rather have the knowledge I did a thorough - if slow job, and can sand/touch-up minor chips inexpensively as necessary with indetectable results.
