undercarriage frame paint/rust protection choices?

Thinking about scrubbing down the frame rails etc on the underside of the Challenger and coating/painting the metal.
What is the best for protecting the underside of the car? PUR15? paint?
Rubberized spray?
How do you guys prep?: de-grease? Rust encapsulate spray?
Thanks
Smos

Anything that labels itself as a rust encapsulator is crap IMO.

Best? Sandblast bottom of car, epoxy prime and undercoat. If sandblasting is not an option I would use a diesel fired hot water pressure washer. That would take most down to bare metal, whatever's left you could hit with a wire wheel on a grinder, then rewash and epoxy prime.

I agree with these fellas

I spent almost the entire summer under my 'Cuda with a torch and scrapper. Got it clean as a babies but. Then sprayed it with Hammerite. Thats some tough stuff. Ain't no easy way to do it.

Dude I have to say, I spent 4 hours one afternoon and had a bare bottom, clean enough to eat off of when I removed undercoating...3 cars so far. I used a steam pressure washer, it's tons easier and better than a torch. Rent one, it's worth it for this job and get your car done this decade.

And entire summer just removing undercoating?