Usually I file this kind of stuff under the "snake oil' category, but POR-15 seems to do what they say. One side of my 39 has a good drip rail, the driver side......not so good. It is pretty evident that some Georgia pine needles or other trash was trapped in the rail and held moisture. There's about an 18" section that had some rot in the bottom, other places on the sides. I was able to weld some sections in for the sides, but the bottom is almost impossible to get to. I DID NOT want to replace the whole rail. Anyway, I used some duct tape to form a dam for under the rail. I cut some strips of metal and laid them in where the rot was. Then I used paper towels to form dams at either end of the rusty area. Out of the shop fridge comes the POR-15 and I poured it into the makeshift mold of the drip rail. Before it dried, I pulled the paper towel plugs out and let the POR-15 flow. It did such a good job I poured POR-15 into both sides of the drip rails. It left them slick and ready for the Pebble Beach concours, where my car will be displayed the same year as they get an ice maker in hell. Now a little glass bondo on the bottom side and we're on to the next challenge. By the way, I'm a pretty fair sheet metal welder as I do it on a part time basis. I can weld to thin metal and I can even weld to rust, but I can't weld to rusty thin metal. Add POR-15 to the bondo, baling wire and duct tape list. I'm packing my suitecase with these and a pair of vice grips and going to Japan now to fix their reactor.