opinions please: treat the surface rust in wheel wells or leave it alone?

[dakota]

I'm looking for some guidance on what to do, if anything, with some surface rust in the rear wheel wells of my Challenger.  There's a triangle-shaped area in both rear wheels where it looks like the original undercoating was either never applied or has worn off.   While I have everything off the underside of the car, now would be the time to act if it's best to do something about it.    I am concerned that any surface coating that I add will end up making a little problem bigger by allowing any hidden rust to keep eating away at the metal.  If I treat it, I'm thinking about scrubbing the wheel well with a soap and a brush to remove as much dirt as I can, cleaning the exposed rusty area with a wire wheel, priming the bare spot, then going over the entire wheel well with an undercoating/bed liner spray.    Other than the area around the mounting points for the final set of exhaust point hangers, there appears to be only surface rust present on the underside.   The small holes around the exhaust hangars mounting point look like they were patched with fiberglass from inside the trunk.   I will have to do some poking around in the trunk to explore this further.

This is not a numbers-matching vehicle or a future show car.   

[moprr]

I would defiantly do something before it spreads,  blasting the spots would be best but anything you do is better than nothing.  Covering it up won't do any good show car or not.

[anlauto]

Krown rust proofing..

[rhamson]

I'm looking for some guidance on what to do, if anything, with some surface rust in the rear wheel wells of my Challenger.  There's a triangle-shaped area in both rear wheels where it looks like the original undercoating was either never applied or has worn off.   While I have everything off the underside of the car, now would be the time to act if it's best to do something about it.    I am concerned that any surface coating that I add will end up making a little problem bigger by allowing any hidden rust to keep eating away at the metal.  If I treat it, I'm thinking about scrubbing the wheel well with a soap and a brush to remove as much dirt as I can, cleaning the exposed rusty area with a wire wheel, priming the bare spot, then going over the entire wheel well with an undercoating/bed liner spray.    Other than the area around the mounting points for the final set of exhaust point hangers, there appears to be only surface rust present on the underside.   The small holes around the exhaust hangars mounting point look like they were patched with fiberglass from inside the trunk.   I will have to do some poking around in the trunk to explore this further.

This is not a numbers-matching vehicle or a future show car.

Knock off the loose rust and treat it with POR15. You will never worry about it again.

[TelisSE440]

Knock off the loose rust and treat it with POR15. You will never worry about it again.

  Clean the rust thoroughly and then put a good rust preventer. Everytime you get a lot of rust, you have to deal with it.

[tommyg29]

Mine had some minor surface rust in a few areas, but about 5 years ago I used eastman products, rust converter and then chassis saver IIRC, and it still looks great. Certainly not "mirrors on the ground" show quality, but great for a driver.
Personally, I would go crazy with a car with an immaculate painted underbody. I have enough trouble keeping the top half looking good. Of course, we can actually drive our cars, which is a great feature in itself