the coatings I would recommend
The best coating available right now on the market is (rust bullet) however it is expensive however it comes with a 10 year guarantee don't ask me the fine print it is around 100 dollars a litre and 3.7 Ltr is 350
I would also highly recommend kbs coatings is definitely better than POR-15
https://www.youtube.com/watch?v=17pakzLfY00
KBS RustSeal is cheaper it is 62.00 a litre and 4 Litres - $195.00 however it requires three steps which will bring the overall price up
STEP #1 - AQUAKLEAN
STEP #2 - RUSTBLAST
STEP #3 - RUSTSEAL
also I forgot to tell you that POR-15 is not UV stable and absolutely requires a topcoat