Thank you for all the feedback. So my understanding and I'll use POR-15 as an example. I brush clean gently the rust spots then use POR-15 metal prep then once dry 100% use the POR-15 rust prevention on the whole body then POR--15 top coat? That's my understanding for right now. And does PoR-15 last a good while 3 years tops before a real paint job as well as is their something better which I think what mustang7173 posted is the better stuff for it.
Don't use por 15--Prep is critical and meant for inner areas not exterior sheetmetal that's going to receive the actual topcoats exterior finishes. There are better easier to use products out there. If your looking to do the exterior sheetmetal epoxy primer is the way to go if the car is going to sit for a long time before actual paint. Simple process sand with 80 grit to bare metal with a oscillating sander-wipe with waterborne wax and grease remover-let sit 1 hour--apply epoxy as per instructions heres my vid on the epoxy primer
