I probably missed that on the rust proofing .. Wd40 will def help get rid of that stuff. I hate degreaser personally because it dries out rubber as well. I like to think of it as a cleaner for engine blocks only from the prehistoric carbureted days where there wasn't so much rubber and plastic underhood. Back then domestic car makers couldn't build a car right let alone valve cover gaskets etc that would leave oil all over the side of the block that would accumulate dirt and debris. Degreaser is good for that.