We made a device to empty all the oil out of the Jack that works like a champ. Cap off the oil inlet to the jack. One hole in the cap has a hose you lower to the bottom of the jack between the piston and the jack. The other side to a drum. We use a vic plug tapped for a hose fitting. You also put a air chuck on the vick plug. Cap off the jack and hit her with about 4lbs of air pressure and all the oil is forced out the hose. Same idea as a keg of beer only not as tasty.