The automatic ATF changer cleans and changes the fluid in the gearbox, torque converter and radiator within 20 minutes. The display, the compact design and the automatic intelligent switch for fluid flow direction ensure an easy operation. The following processes are automated: the filling, the detection of polarity, the cleaning and the transfer function. The fluid pressure of the A/F cooler and the outlet pressure of the device are displayed during fluid change. The different oils remain completely separated in the interior of the device and cannot mix.