Perrin Air/Oil Separator | 2002-2007 Subaru WRX/STI w/ TMIC (PSP-ENG-605)

Perrin Performance
Looking for the lowest price?

Give us a call to get the best prices and parts for your build. Or, just call us with a cool racing story...either way we're here.

Phone Call or Text 651-927-4510

Email -

Fits Your:
FREE Delivery Expected by , when ordered within hrs and mins
 Need Help Getting Started?
Call Or Text Our Experts at 651-927-4510

$486.20 $572.00Instant Savings of 15% ($85.80)

Earn  $9.72 In MAP Rewards!

Air/Oil Separator for WRX/STI with TMIC by Perrin

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. A 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 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. A By keeping the air oil separator the same temperature as the blow-by, water condensation is significantly decreased, allowing oil, air, A 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.


  • 2002 - 2007 Subaru Impreza WRX (TMIC)
  • 2004 - 2007 Subaru Impreza WRX STI (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



  • Manufacturer's Warranty

Customer Reviews

Based on 1 review
Peter S.
A dose of reliability for your EJ

Install was straight forward and it seems to have no issues!