The Crawford 08+ WRX Air/Oil Separator effectively removes the oil from the air coming out of the engine’s ventilation system via a two stage process: - The first step in the process is a large volumetric swirl pot. The function of the swirl pot is to use centrifugal force to remove the oil from the air. The air is then passed through a second chamber (see second step below), and extracted through the top of the AOS. Gravity then sends the remaining oil down the walls of the swirl pot and collects in the bottom of the AOS. At this point the separated oil sitting on the bottom of the AOS is returned to a baffled chamber in the center of the engine block. - The second step involves a second chamber located within the first chamber. As the separated air moves up inside the AOS, it must enter the second chamber before it can vent out the top of the AOS. The function of the secondary chamber is to remove any residual oil that may have made its way up the swirl pot. The secondary chamber also has a drain to return any separated oil back to the engine. The Crawford V2 AOS incorporates an internal heater to keep the AOS operating at the proper temperature. The coolant line that runs from the turbo to the engine is now re-routed through the AOS. The effectively equalizes the temperature between the AOS and the engine to avoid condensation which can occur within any AOS. This heater also makes sure the vaporized water leaving the motor makes its way through the AOS in vapor form, rather than condensing back into a liquid. This is a MUST in cold weather and a bonus for any climate. NO OTHER AOS ON THE MARKET EMPLOYS THIS TECHNOLOGY!