Por 15, rust oleum, tractor implement paint, what to use on rusted metal

I looked at rust prone areas where water will go and rust will grow and thought "rust reform and/or inhibit applied like the water". So that's what I did. First use was years ago and a product called Neutra-Rust. Most recent is called Rust Ender. I've applied it with a brush, a pump spray bottle, and even poured it from the gallon jug. Used a little compressed air to push it too. Places like bottoms of quarter panels, bottoms of doors, hood, trunk lid, all those places where a body skin is folded over a substructure.
I've used it on rear ends, brake drums, and leaf springs too. None of this is meant to get a top coat of paint or any further effort. It does what I want to do, stops the current rust and prevent further/future rust. Next application will be vert rear seat spring frame assemblies ( that will be fun LOL ).