Apparatus and method of replacing old fluid in a transmission system by feeding clean fluid into the system from a clean fluid tank using a pump and draining the old fluid into a waste tank and using a processor to monitor the clean fluid pressure in the clean tank and the old fluid pressure in the waste tank and adjusting the pump's speed using the processor such that the old fluid is drained at substantially the same rate as the clean fluid is fed.

An apparatus for changing oil in a vehicle having an internal combustion engine with lubrication passages, the apparatus having a system for air purging the lubrication passages to expediently remove the oil. The apparatus includes a pressure transducer in the fluid line of the air purge system to monitor a pressure drop of the compressed air when the spent oil has been removed from the engine. When the pressure drop exceeds a predetermined value the air purge system automatically deactivates.

Methods and apparatuses are provided for servicing a system having a used fluid, an inlet and an outlet. An exemplary apparatus comprises a first hose capable of being connected to the inlet, a second hose capable of being connected to the outlet, a first fluid tank including a first new fluid, a second fluid tank including a second new fluid, a pump and a selector. The selector selects one of the tanks and the pump pumps the new fluid from the selected tank into the system through the first hose and the inlet, and the second hose receives the used fluid via the outlet. For example, the first and second fluid tanks may communicate with the pump via first and second valves, respectively, and the selector may open the first valve and close the second valve, so that the pump pumps the first new fluid from the first fluid tank.

An environmentally sound apparatus for automatically extracting and injecting lubricating fluids is disclosed. The apparatus includes one or more sources of lubricating fluid, a waste fluid tank, and a source of compressed air, all with associated fluid-level sensing status switches, as well as other status switches for vacuum and low battery voltage. Signals from such status switches and from a fluid flow monitoring pulse meter are relayed to a central processing unit which operates through a front control panel to control a valved single pump and a plurality of valved lines in fluid communication with the single pump, and to display error messages to front control panel indicators when appropriate. Waste fluid is evacuated, from a crankcase oil pan of an internal combustion engine through one computer-determined arrangement of open valves and fluid lines, to the waste tank. Fresh fluid is injected, from one of the fluid sources through another computer-determined arrangement of open valves and fluid lines, to the oil pan. Quantities of both evacuated waste fluid and injected fresh fluid are at least periodically monitored and displayed. The system is also automatically cleared and purged of residual fluid. Evacuation, injection and clearing operations are initiated by an operator and executed automatically through status-monitored sequences controlled by the central processing unit. All fluid exchange sequences are performed without exposing the operator or the environment to either waste or fresh fluid.

Apparatus and method of replacing old fluid in a transmission system by feeding clean fluid into the system from a clean fluid tank using a pump and draining the old fluid into a waste tank and using a processor to monitor the clean fluid pressure in the clean tank and the old fluid pressure in the waste tank and adjusting the pump's speed using the processor such that the old fluid is drained at substantially the same rate as the clean fluid is fed.