Perrin 02-07 Subaru WRX/STI Red Air Oil Seperator (perPSP-ENG-605RD)

Regular price $572.00 USD $461.89 USD

Ready To Ship! Special Order! Ships in 6+ weeks

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Part # perPSP-ENG-605RD

Before it reaches the intake, oil from the crankcase vents is captured by the PERRIN Air Oil Separator, which also lowers carbon buildup, boosts intercooler efficiency, and lessens the possibility of performance-robbing detonation.

The AOS decreases the quantity of oil deposited into your intercooler and intake system, increasing intercooler efficiency! Your intercooler will become less effective as blow-by and oil buildup inside of it because less heat will be removed from your engine. Detonation and power loss resulting from this might harm your engine.

Reduce the accumulation of carbon in your intake valves, combustion chamber, and other areas. Crank case blow-by is circulated back to the intake so that the engine can consume it, but while doing so, it becomes lodged in the intercooler, intake valves, and tract. This accumulates over time, resulting in a loss of power and more strain on your valve train.

Oil has a very low octane rating. When you put a lot of engine blow-by (oil) back into your engine, it lowers the octane level of your fuel, which can cause detonation or knock, which can result in loss of power and engine failure.

Using a PCV on the AOS outlet provides appropriate crank case venting during light loads and helps limit unwelcome blow-by gases into your intake system, which is why we built the PERRIN Air Oil Separator kit around this concept. Utilizing a PCV maintains your intake tract clean and lessens exhaust smell.

Over the years, a slight buildup may occur inside your AOS. This can be quickly taken care of by removing one bolt to access the inside for cleaning. This small feature is one of the many things that makes the PERRIN AOS stand out from the rest.

The base plate of the AOS is heated by coolant drawn from the engine. By keeping the AOS at the same temperature as the engine and blow-by gases, water condensation is decreased allowing oil and water vapor to separate and pass through the can. This vital feature eliminates nearly all the sludge that can build up in the AOS body, which drastically reduces how often you must clean it.

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


  • 2002-2007 WRX - 2002-2005 WRX installation requires the removal of the cruise control module.
  • 2015-2020 WRX - Modifications may be needed if installed with an after-market air intake box, contact tech for further details.
  • 2015-2020 WRX- Does not work on vehicles with EyeSight.
  • For left-hand drive cars only.


  • Subaru WRX/STI (2002, 2003, 2004, 2005, 2006, 2007)


  • Increase Intercooler Efficiency
  • Reduce Carbon Buildup
  • Reduce Detonation
  • PCV System Included
  • Easy Disassembly For Cleaning
  • Heated By Coolant
  • Powder coated for protection against the elements, the textured finish will look awesome for years to come


  • (1) PERRIN Air Oil Separator
  • (1) Car Specific Bracket
  • (1) PERRIN License Plate Frame
  • All necessary hardware for installation
  • Warranty & Instructions

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In stock, non special order items can be returned within 30 days of the product arriving to your house or place of work.
Returns will NOT be accepted on Clearance Items, Final Sales, Special Orders, Opened, Installed, Incomplete, or Otherwise Used Products. In order to initiate a return, an RMA number must be requested and approved via e-mail.
All returns will be subject to a 20% restocking fee minus complete shipping cost (roundtrip).

Any processed orders that have not shipped will incur a 6% cancelation refund fee unless the product was not available to ship within a timely manner. No fee will be incurred if used as store credit.

For complete details on our return policy, please see our Help and FAQ link under HELPFUL INFO.

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