The transmission drain plug takes a 17mm hex key to remove. Being frugal people, we decided to make our own. Rooting around in the tool box we discovered a 3⁄4-inch hex key lying in the bottom. We cut off a piece approximately 11⁄2 inches long and then filed down each side until it fit into the plug. A 3⁄4-inch open-end wrench allows us to get in there and turn the thing.