I have looked around for this answer, and either it really hasnÆt been addressed yet, or I am just missing the boat, probably the later. What if anything is needed with POR 15 to treat metal that has surface rust and light scale? I have seen several kits on a few different web sites, and then I see just paint by itself. I have read on the POR-15 site to go through their 4 step process using all of their products, but I am looking for some feedback from people who have actually used the product. So far I have heard nothing but good things about it, but I am not sure what and how much I need to buy.