Not if it was done right. I have the skid plate from the first Jeep I ever owned. An early '80's CJ-5 if i remember, anyways, not it mid '90's. It has the POR-15 on it and I wanted to see if it was any good. I left it outside under a Willow tree. Every year a layer of soggy leaves fall on it and act like a sloppy sponge until spring when the leaves get mostly blown off. It is a bit sun faded, but no rust! No chipping, peeling, or anything. So if I saw it on a Jeep I was looking to buy, and it looked to be applied right, I wouldn't hesitate to buy it. BUT if I saw any indication of cracking or rust underneath then I would walk away. If any paint like product was inside the frame I would pass on that too. If rust ever shows up under it inside the frame there is no way to fix that.
