I followed a very specific procedure for this protection, and after a year of use, I can say that it's held up perfectly. So if you're looking for a sure fire way to prevent rust, this is it.
After deciding which parts you want to paint with POR-15, strip away as much as possible from the area you plan to paint. This paint is really extreme, if you get any on a screw and it seeps into the threads, you'll never be able to remove that screw, ever. It's a chemical bonding paint.
Day one: Using soap and water and a brush, scrub and wash everywhere you plan to paint to remove any loose dirt and grime. Then I sprayed Simple Green all over, and using a wire brush wheel attachment on a portable drill I thoroughly scrubbed the surface, but not so hard as to remove the factory paint or protective finish, just hard enough to remove any remaining grease and dirt. Rinse it all off very thoroughly with the hose and allow it to dry over night.
Day two: When the surface is 100% dry, apply the paint in thin coats, and follow the instruction on the paint can for how frequently to re-apply multiple coats. I did three coats of POR-15 and allowed it to fully cure for a week.
|POR-15 finish rear wheel well|
|POR-15 & rocker guard on front wheel well|
|POR-15 & rocker guard on frame rail|