I recently bought a 93 Ford Ranger I'm doing top end work to it this summer, repainting it, and I'm looking into painting the frame because it is rot free and I'd like to keep it that way seen as I'm in MA, and it only has some surface rust on the frame. I don't care very much about how long it will take because it doesn't need to be on the road until November, but cost is an issue. I was thinking of just hand sanding it down then either spraying some black Rust-Oleum on or brushing it on. I was wondering what you all think of this idea and what you had done to your frames? Also I'm painting it while the body and frame are still connected.

 

not very cost effective but POR15 is great paint if properly applied to chassis components and frames. but i wouldnt apply it while everything is connected. but for what you are describing, i would just pick up some black rocker guard and some tar spray bombs to give everything a nice new coat of black. tar coating also sticks to rusty and oily surfaces without prep, then if you choose to oil spray it later the tar undercoationg will help absord more of the treament later on and help with corrosion resistance. i do this to my truck alteast once a season, really cleans it up..

 

I second the POR15. that is the way to properly do the job right the first time and it will likely outlive the truck.

 

POR-15 and be sure to top coat it with someting also, either one of POR's products or something else like Rustoleum or Hammerite.
MikeR