Maybe it was just the can. But it stayed out chunky at times to make the finish horrible. I shook the can before and during my painting. Had to resand it and used other paint. It just didn't turn out I have been painting for 40 years it's been a long time since I had a crappy finish

seems to rust right through it

Not quite the same paint as POR-15 Rust Preventative paint Black.
I understand the need for different final coat colors, especially when needed for UV protection, but this stuff is a different paint than the original POR-15. As others have noted - this top coat flows in very strange ways. In some ways it seems like it continues to flow for many hours, so when painting any vertical surface with it - be careful as it will continue to flow, drip and run long after you think that you have brushed out a nice smooth surface.
Like Black POR-15 this settles and smooths out fairly quickly, so it is great for hiding brush marks. The issue is that it does not stop flowing for many hours. I was painting a large steel tank 14"D x 45" long and so I used original POR-15 to cover all rust spots and bare metal. That paint has it own very unique flow qualities but I have used it long enough to know how to use it. Also know that within a couple of hours it has started to dry enough to stop flowing. But this White Top Coat is different. I VERY carefully brushed it out so it was applied evenly and it looked great But then hours later I check it and it was full of runs & drips. So be very careful when applying to any non-horizontal surface.
Also believe that this white Top Coat has a different chemistry, as you can thin it and clean brushes with regular Mineral Spirits. No way with Original POR-15 Black which is almost impervious to Mineral Spirits. For example - the brush I used for this Top Coat I could store in a small can of Mineral Spirits and it would remain soft and usable again. But for brushes used for original POR-15 they just hardened rock solid in the same container.
I love POR-15 but be aware that this is a different paint.

Very good product. Nozzle clogged but once I found a replacement if worked fine

Paint everything with it! Wear a good mask.