POR15

ya you can brush it on.  I would sandblast but if you do not have than a wire wheel on a side grinder then sand untill your satisfied. but to me it sounds as though you have some surface rust i would sandblast it off even if you have to rent a sandblaster for a weekend.

I just have a bit of surface rust in the common spots ( frame rails, trunk and floor pans) places like that, I was reading on there website and it says that it stops rust and even fills pin holes, just wondering if it is true ? thanks

Like azz7772 said I would try and remove the surface rust i.e. 4 1/2" wire wheel on an angle grinder. You would have to be able to get to both sides of the surface to seal it from spreading. I brushed it on the RR and you can't tell it was brushed. Forms a very hard plastic like coating. I plan on doing the same with the Dart. Also the sealer is not UV friendly.

Tom

Just like paint prep is key.

I suggest you use their MetalReady for prepping surface. Its basically phosphoric acid and zinc. After a couple minutes, the acid etches the metal and the zinc bonds to the metal. Just rince off to neutralize. Worked great on my floor pan

Fred

I used Ospho to treat any marginal spots and a 4.5" cup wheel. Brushed on the Por15 and then top coated with Rustoleum Semi-flat black. Looks nice.

Andy