POR 15 on body panels?

Have any of yall used POR 15 on a body panel? I thought I had the rust on my roof killed out before I painted it,but not so as it is coming back and pushing off my 2 year old paint in a few spots. The Dart had a vinyl top before but I got rid of it. I am going to have to repaint an dwas wondering about POR on top of car.
Author: admin