The cork works great if installed correctly. (Cork and rubber mixture) on a lot of things and they do not leak. You spray the pan surface with the yellow weather-stripping glue and only one side of the gasket. I use cork or corapreme (cork and ruwhen it gets tacky you put them togather. When you assemble the pan to the transmission you insure that there is no oil or any kind of gasket sealer on the mating surface. If there is the cork will squeeze out of the sealing area. I even install the gaskets completely dry and they work great. Only have trouble when I use any kind of gasket sealer.