My underbody isnt that bad but I have some rust by the fuel tank and my rear and and axles are all rust colored. I want to paint my rear end and fuel tank and maybe around it black, I dont know much yet about cars so I cant take stuff off. A guy at work who has a 74 gto said to use por 15 and that you just use a paint brush?

 

Yes, use POR15...but make sure you knock any loose rust scale off first. A cup wire brush on an angle grinder works great for that.

 

POR15 put on by a paint brush will be flat black. Put on by a paint gun will be gloss black. I sprayed the frame of my first chevelle with the stuff after sandblasting it. I've also got it sprayed on the rear end in my current chevelle. It's pretty good with rust but not as damage resistant (chips/dents/scratches) as they say it is.

 

ya Im not pulling out all my rear end stuff so I will have to use a brush, Why would it matter though of gloss if i used a paintgun or brush?

 

Some people like the underbody of the car to look just as good as the rest, that's why the gloss vs. flat matters.