I'm one that had bad results. Followed the directs to a 'T' since it was so dang expensive and, if anything, the rusting process seemed to speed up under the treated area. Where I had pitted metal when I applied it, a few years later, there was a gaping hole.

This was on a trunk pan, out of the weather, and not even getting wet from the underside as it was above the gas tank.

I have a pair of fenders in storage I need to pull out and take pics of. One fender I painted with just plain ol' Rustoleum the other POR15........20 yrs later, guess which one shows rust. Neither fender has been on a car since painting, always stored inside out of the weather.

Straight up crap.

I'd like to believe the formulation has improved in the 20 yrs since I last used it, but, I know it hasn't.