POR-15 is great stuff. Are you using this as a rustproofing or is there definetly rust that you are covering. POR-15 is meant for rusted metal. If it's too be used on clean metal, the metal has to be prepped with their "Metal-clean". Also, since you can't really see inside the rockers, it would be impossible to see if everything got covered. If you have never used this stuff before, let me give you a heads up. Anything, and I mean anything, that you use to apply the stuff will be ruined. You will not be able to clean out a brush or anything, once this stuff starts to dry. I had a brush that hardened so much, I was able to use the brush to cut into a piece of pine. Nothing will clean/dislove this stuff. I even let the brush soak in gasoline for over a week, and it did nothing. So if you use a garden nozzle, kiss it good bye.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section