Well POR works well but you need to sand down the frame to bare metal. Eastwood has some stuff for frames that is pretty good from what I have heard, but never used it. I would personally just hit any rust starting on the floor boards with it after grinding/sanding the worst stuff off. I did POR under my truck originally when I got it, to keep more damage from happening. I just got the floor fixed in a couple spots that were bad before I bought it and used Zerorust aerosal spray cans on the bare metal. Much cleaner then brush on IMO.
Hit the rust areas with your choice of stuff...ZR, POR, etc. I nailed the under side areas that were painted and no rust with Restoleom gloss black... s coats and them used a cheapie $2-3 a can undercoating on decently thick. IMO remove any rust if possible... treat the area, and then layer, layer, layer. That's my $.02 worth oin dealing with MN salt
-Mikey
1987 Chevy K5 Blazer- 350 TBI
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