Perrin Performance - Air Oil Separator - 08-14 Subaru WRX / 08-21 STI with TMIC

Perrin PerformanceSKU: PSP-ENG-606BK

Sale price$486.20

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Perrin Performance - Air Oil Separator - 08-14 Subaru WRX / 08-21 STI with TMIC


The PERRIN Air Oil Separator is not a catch can. Catch cans capture engine blow-by and stores it in a container, which requires constant attention and removal of oil every few hundred miles. The air oil separator separates the oil from the air, draining it back to the engine, which eliminates the need for constant attention and draining of oil. As oil drains from the bottom of the PERRIN Air Oil Separator, clean oil-free air vents out of the top to rejoin the intake tract.

The PERRIN Air Oil Separator features swirl pot technology and multi-layer baffles. This design forces incoming engine blow-by to move rapidly across the baffles, separating oil from the engine blow-by. Multiple layers of baffles means more surface area to collect more oil, making for a compact and efficient design. Oil entering from the crankcase vents spins counter clockwise through the entire body of the AOS, passing along four walls equaling roughly 50 sq/in of surface area. The multiple baffle walls in our compact design simulate the surface area of an AOS that is 13.5" tall!

The base plate of the the air oil separator is heated by coolant drawn from the engine. The heats the entire air oil separator to the same temperature of the engine blow-by. By keeping the air oil separator the same temperature as the blow-by, water condensation is significantly decreased, allowing oil, air, and water vapor to separate and pass through the body. This vital feature eliminates nearly all the sludge that can build up in the air oil separator body, which is a common problem with catch cans and other air oil separators.

Powder coated for protection against the elements, the textured finish will look awesome for years to come. The PERRIN Air Oil Separator is available in black or red texture powder coating.

Please Note: The Perrin WRX/STi Air Oil Separator is Designed for Left Hand Drive Vehicles Only.


  • 2008 - 2021 Subaru STi (TMIC)
  • 2008 - 2014 Subaru WRX (TMIC)


  • Swirl Pot Technology
  • Heated By Coolant
  • Increased Intercooler Efficiency
  • Reduced Carbon Build-Up
  • Custom Drain Back Crank-Case Fitting
  • Powder Coated Finish

What's In The Box?

  • 1 - Perrin Air/Oil Separator
  • 1 - Mounting Bracket
  • 1 - Perrin License Plate Frame
  • All Necessary Hardware
  • Warranty Information
  • Stickers

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