The Original Air/Oil Separator

Not just a catch can, the Crawford Performance Air/Oil Separator routs oil back where it's supposed to be. Forced-Induction (Turbo) motors, especially horizontally opposed ones like Subaru, are notorious for burning and consuming oil. This was even more apparent at the track where Quirt Crawford began to ponder how to remedy this nagging issue. Tested and proven with multiple race teams and street applications, the first ever Air/Oil Separator was released in 2006. Being spoiled in sunny southern California, we didn't realize that cold climate applications would see condensation. This is when V2 was released to ensure efficiency in all weather conditions.


In the stock configuration, the crankcase is vented to the intake system in three different places. Each of these vents have a baffle system built within the motor to minimize the transfer of oil to the intake, but some oil can still make its way into the combustion chambers. When the oil enters the combustion chambers, it effectively lowers the octane of the fuel, leading to detonation.

Our 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. Our Version 2 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. This 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!

See FAQ for even more information.