Best way to go about fixing the undercoating in the wheel well? From what I can tell it seems mostly rust free as none of the paint appears damaged. Would the usual spray on rubberized coating be appropriate? I've seen a lot of posts saying not to this as it can lock rust/moisture in and exacerbate any issues. I've also since done a black fluid film coat but as expected it just washed off going through usual rain and wet roads. Perhaps black cosmoline RP342 would be good? A little more resilient to the elements while being black and a rust inhibitor.

 

This is what I used on my BMW 2002s that I restored.

 

Elbow grease and bedliner.

 

3M undercoating

 

To each their own, but I hate that stuff. It's messy and doesn't harden. Scrapes off too easy.

 

Raptor liner or some sort of 2 part urethane undercoat will work after the appropriate prep (I feel sorry for whomever is doing it).

Don't use the 1 part spray cans you can buy at a store. They will fail, trap moisture, and cause rust.

 

I've had bad experiences w cheap stuff that never hardened. Total mess.

But the 3M stuff has always been the best. Hardens, yet remains flexible so doesn't flake off. Goes on as thick as you want.

Highest quality undercoating I've found.

 

Would this be similar to Rockerguard? I applied this stuff many years ago on a different car but didn't hold on to it long enough to see if rust was going to come through or not. It did look great once applied, but like others have said, I don't want to lock in moisture and eventually have it explode with rust.