Skip to product information
1 of 1

Kthnxbye Racing

Crawford FMIC Air Oil Separator Black 2002-2007 WRX / 2004-2007 STI

Crawford FMIC Air Oil Separator Black 2002-2007 WRX / 2004-2007 STI

Regular price $356.20
Regular price Sale price $356.20
Sale Sold out
Shipping calculated at checkout.

The Crawford Air/Oil Separator effectively removes the oil from the air coming out of the engine’s ventilation system via a two-stage process: 

The Crawford Performance Air Oil Separator (AOS) is the original solution to Subaru's notorious oiling system issues. Although the technology was pre-existing with other vehicle brands such as Porsche, Crawford Performance is the inventor of the first system specifically for Subaru. No other AOS on the market employs the same technology.


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 newest version of the air oil separator features a coolant line pass system, which helps eliminate milky residue when driven in cold climates or short trips. Making this ideal for any street-going car, or full-blown race car!


  • Not a Catch Can - Closed Loop and Maintenance Free
  • Consume Less Oil
  • Extend the Life of your Engine
  • Reduce Detonation and Risk of Engine / Ringland Failure
  • Reduce Fuel Dilution and Subsequent Power Loss
View full details