Abstract: A system for the emptying, replenishing and testing of oil maintained within an oil reservoir of a crank case of a compressor unit having an external casing for purposes of housing the compressor motor wherein the interior of the casing is maintained under a positive pressure due to refrigerant entering the casing as it returns from the evaporator. An access valve is disposed on a free end of a conduit having the opposite end thereof disposed in direct access to oil within the oil reservoir. A valve opening structure, when applied to the access valve will position it in an open or flow allowing position, allowing the oil within the casing to pass through the conduit and out through the access valve due to the positive pressure within the casing. The oil may be replaced by securing a liquid pump in fluid communication to the conduit so as to force the access valve open. Upon the pressurized input, from the pump, oil flows back into the oil reservoir against the internal pressure within the casing.