I used it on the frame and underside of the body of my 53 Ford convertible. Worked well and still looks good. Everything had been sand blasted and metal repaired first, the POR still has a nice shine to it. Wear a good set of rubber gloves, that stuff will stick to your skin for a long time.
I used one half a can and went back about two weeks later to use the other half. Couldn't get the lid off. The other half was rock hard when I did get the lid off. I would store unused POR in a mason jar but don't get any on the threads.