Abstract: Apparatus and method for maintaining viscous liquid sealing substances such a grease adjacent and in contact with seals utilized in pneumatic cylinder-and-piston actuators for oil and gas well swabs, the structure including a piston member which is slideable on the piston rod and which includes an external O-ring for sealing engagement between the cylinders and the piston member and an internal O-ring which is in sealing engagement between the piston member and the piston rod. The piston member is resiliently urged by a compression spring towards the actuating piston and the viscous liquid is trapped between the actuating piston and the slideable piston member. A further like slideable piston member may also disposed on an extension of the piston rod on the opposite side of the actuating piston which is also urged towards the actuating piston. Viscous liquid is trapped between the latter slideable piston member and the actuating piston.