I bought a can of black paint over rust for my differential cover. However i never used it. Its just sitting there. The can says to sand it down then paint it. From what i read online there is no paint you can use to paint over a rusted area that stops the rust because it just continues rusting underneeth the paint.

Im not sure if this is true or not, because rust needs moisture to continue rusting i think, and if you paint it IMO i think it should stop but im not an expert. IMO, that roof looks like its totally gone. Maybe you could sand it down to get the surface rust off like i did to my Jeep. The Jeep lost its clearcoat and the paint washed off and started rusting on the outside in a few spots got to the size of your forearm almost i sanded it down to bare metal and painted right over it and the paint has been holding for like 7 months now. So i think its fine.

 

For your floor, I'd put POR 15 on after you have wire brushed and sanded off the majority of the rust. After that I would put down a good bedliner. Make sure to keep it out of any mounting holes.

The bedliner would deaden the sound and it's fairly easy to clean up. Along with the fact that it's made to be exposed to the sun. Your cab floor will still see sun at times and the U-V activity of por-15 may give you a undesirable finish.

 

Rust or corrosion happens when the base material reacts to oxygen, weather it is aluminum iron or plastic. Everything "rusts". Water is just a more condensed form of O2 it also acts as a mild acid and accelerates the oxidation. I am unfamiliar with por-15 but if it forms a neutral based oxygen barrier then it will do the trick. I would recommend painting over it to help protect the por-15 from scratches an abrasive wear as paint would provide a harder finish, I know rustolium makes a conversion coating as well it seems to do good at stopping rust but is very soft and wont stand up to well to anything so it has to be coated with paint to protect it.

I would definitely recommend opening up the hole to get all the rotted metal out and to coat the underside of your cab to make sure she don't rust through. Definitely pull the carpet and check there too the last thing you want to do is let any rust spreed farther from putting it off.

 

thanks for all the good info guys. Ill definatley be puling the carpet up as soon as I can get some time. I've been working 11 hour days so I have money to fix this stuff. When I bought this truck I was looking for a project to tinker with here and there but I never thought I'd be taking the whole interior out to make sure I wasnt gonna fall through the floor while im driving down the road. the weathers been getting nicer out in the 40's today so maybe I can get a start on it this weekend.