PERRIN Air Oil Separator red anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator red anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator red anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator red anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN red Air Oil Separator installed in 2002-2021 Subaru WRX/STI engine bay.
PERRIN Air Oil Separator black anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator black anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator black anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN Air Oil Separator black anodized aluminum for 2002-2021 Subaru WRX and STI.
PERRIN black Air Oil Separator installed in 2002-2021 Subaru WRX/STI engine bay.
SKU: PSP-ENG-620RD

Air Oil Separator for 2002-2021 WRX, STI

Sale price$449.65 Regular price$529.00
IN-STOCK
Color:Red
The PERRIN Air Oil Separator removes oil vapors from crankcase gases before they reach the intake manifold. Its ceramic-coated, CNC-machined design reduces carbon buildup and supports engine health.

PROPOSITION 65

Proposition 65 Warning

WARNING: Handling passenger or off-highway motor vehicle parts can expose you to chemicals such as phthalates and lead, which can cause cancer and reproductive harm. To minimize exposure, service the vehicle in a well-ventilated area, wear gloves, and wash your hands.

For more information see: www.P65Warnings.ca.gov/motor-vehicle-parts

OFF ROAD USE ONLY

This product is legal in California only for racing vehicles which may never be used upon a highway. Check your local and federal laws prior to installation.

ESTIMATED DIY INSTALL TIME:
180 MINUTES
EMAIL OUR TECH DEPARTMENT:

Download Instructions

Specs & In The Box

In The Box

Warranty

5 YEAR WARRANTY

Warranties

The ASMC, LTD. (dba ALTA and PERRIN Performance) warrants to the original retail purchaser (“Purchaser”) who holds title to the vehicle on which the parts are originally installed will, when delivered, substantially conform to the respective written Product description furnished to Purchaser, and all PERRIN Performance & ALTA Performance brand products to be free from defects in material and workmanship (excludes cosmetics, coatings and appearance and applies only to the function of the Product for it's intended manner and purpose) within a sixty (60) months period from the date of purchase (purchased on or after October 1st 2010) and will perform in accordance with provided original operating instructions if properly installed, used and serviced on passenger cars. Should a product(s) become defective within such period, Purchaser at its cost shall submit its claim and the defective Product to ASMC, LTD. with an accompanying Return Manufacturer Authorization number (RMA) and the sales receipt stating the defects and the circumstances under which the defect occurred in which case ASMC, LTD. will examine, and upon establishing Purchaser’s validity of claim, at its sole discretion repair the Product(s), exchange the Product(s), or refund the purchase price, which shall fully satisfy and discharge any and all warranty claims. Warranty related inquires should be addressed to the following address: ALTA and PERRIN Performance c/o Warranty Service 3111 NE Shute Rd. Hillsboro Oregon 97124. This warranty extends only to the Product(s) installed in such vehicle model as specified for the respective Product(s) and does not extend to any Product(s) (i) which has been used or operated inconsistent with it’s intended use, (ii) has not been properly installed by a qualified licensed auto mechanic experienced in the installation of the Product(s), (iii) installed in a vehicle that has been used for racing or off road use (Product(s) specifically designated for “off-road“ use only may be submitted for warranty claim. ASMC, LTD. holds sole discretion to warranty claims on those Product(s) not to exceed sixty month limitation above.) , (iv) which was modified or repaired by anyone other than ASMC, LTD. personnel, (v) damaged because of misuse, neglect, accident or improper installation or service, (vi) Sold or used outside the United States of America. No warranty of fitness for a particular purpose is made. In addition, the forgoing warranty shall NOT apply to all components not manufactured by ASMC, LTD. Manufacturers and user of motor vehicles incorporating ASMC, LTD. products should at all times take necessary precautions against damage to persons or property resulting from malfunction of the products.

THE WARRANTIES SET FORTH HEREIN ABOVE ARE IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED. THE SALE IS MADE ON THE EXPRESS UNDERSTANDING THAT THERE IS NO IMPLIED WARRANTY THAT THE PRODUCTS SHALL BE FIT FOR ANY PARTICULAR PURPOSE. THE PURCHASER ACKNOWLEDGES THAT THERE ARE NO WARRANTIES, WHICH EXTEND BEYOND THE DESCRIPTION HEREIN. IN NO EVENT SHALL ASMC, LTD. BE LIABLE FOR CONSEQUENTIAL, INCIDENTAL, OR SPECIAL DAMAGES, AND DAMAGES ARISING OUT OF THE PURCHASE, UNLOADING, HANDLING AND THE USE OF ANY PRODUCTS, ALL OF WHICH ARE WAIVED BY PURCHASER AND IN ANY EVENT, DAMAGES HEREUNDER SHALL BE LIMITED TO A MAXIMUM OF THE PURCHASE PRICE OF THE RESPECTIVE PRODUCT. THIS WARRANTY GIVES THE CONSUMER SPECIFIC LEGAL RIGHTS AND THE CONSUMER MAY ALSO HAVE OTHER RIGHTS, WHICH VARY FROM STATE TO STATE.

Special notes about exhaust related products:

We will not warranty any exhaust part that either fails or has warped flanges due to header wrap being installed. While header wrap protects the engine from heat as well as provides some performance benefits, it greatly reduces the life of any stainless-steel part. Header wrap greatly increases the rate of corrosion, added to that the actual temperature of the metal is much hotter, reducing its lifespan even further. Operation of vehicle without installation of splash guard will void warranty.

We will not warranty any flanges that are warped away from the weld if any aftermarket gaskets are used. Only OEM Subaru / Toyota gaskets are to be used on PERRIN Exhaust parts, excludes downpipes for turbo kits. Subaru / Toyota provides the proper crush gasket that still becomes flat when tightened (or over tightened) in comparison to aftermarket gaskets which can have a crush ring that is too thick, causing a hot-spot in the middle of the flange. These will warp the flanges of your PERRIN exhaust, causing a permanent exhaust leak that will not be fixable with a new gasket.

Special note about suspension & emissions related products:

Many modifications (and combinations of modifications) are not recommended and may NOT be permitted in your country, state or other form of local government. Consult your owner's manual, instructions for each product and all laws before undertaking these modifications. The owner and user are solely responsible for the legality and safety of the vehicle you modify using these components! ALTA and PERRIN Performance are not responsible for any physical or financial damages as result of proper or improper installation, usage or ownership of this product. Use of suspension products will result in a change in the handling characteristics of your vehicle. As with ANY vehicle, extreme care must be taken to prevent loss of control or roll-over during all driving maneuvers. Always wear seat belts, and drive safely, recognizing that reduced speeds and specialized driving techniques may be required. Failure to drive this vehicle safely may result in serious injury or death! Once installed do NOT drive the vehicle unless you are familiar with its unique handling characteristic and confident in your ability to maintain control under all driving conditions.

All engine and exhaust components (Including but not limited to the following, turbo systems, ECU Tuning, exhaust pipes, intake systems, supercharger pulleys, intercoolers etc.) have been designed and are intended for off-road applications only. These components are legal in California for racing vehicles only, which may never be used on public roads or highways. Federal and many state laws prohibit the removal, modification or rendering inoperable of any device or element of design affecting vehicle emission or safety in a vehicle used on public highways. Violation of such laws may subject the owner or user to a fine or penalty. Check your local and federal laws prior to installation! Installation of performance products may void vehicle warranty coverage, if any, on your vehicle. Vehicles modified by the use of performance parts may no longer be lawfully used on public highways. Re-sellers, installers and end users assume all costs and risk associated with these items. ASMC LTD. is not responsible for any losses incurred from the use of any and all products sold.

If you have ANY questions about a product or service, you must contact us prior to installation or use!

PERRIN Performance
3111 NE Shute Rd Suite 101
Hillsboro, OR 97124
Ph: (503) 693-1702



Compatibility

* Please note that after installing an AOS, 2002 to 2005 WRX models will lose the ability to use cruise control

Returns

We stand behind every order. Returning something should be easy.

Refund & Returns 

We offer free returns on all eligible domestic orders within 30 calendar days of delivery. Here is what that looks like:

  • Free return shipping : a prepaid label is issued through our online returns portal. No cost to you.
  • No restocking fees : unopened items in original packaging are refunded in full.
  • Store credit for installed or used parts : full store credit issued, no restocking fee.
  • Customer-damaged parts : a 50% damage fee is assessed; the remainder is issued as store credit.

How to Start a Return

You can submit a return request directly through your account on our store:

  1. Visit our How to Start a Return page, or go directly to account.perrin.com, then continue with the steps below.
  2. Sign in by entering your email address and clicking Continue.
  3. Check your email for a six-digit verification code from our store and enter it on the sign-in page.
  4. Find the order you want to return and click Request return. 
  5. If your order has multiple items, select the items you are returning.
  6. Choose a return reason and add any notes, then click Request return.

Once your return request is approved, you will receive an email with a prepaid return shipping label and instructions. After the item is received, your refund or store credit will be processed.

Need help? Email us at sales@PERRIN.com or call 503-693-1702 during business hours.

Items That Cannot Be Returned

The following are not eligible for return or exchange:

  • Electrical parts
  • COBB AccessPORTs
  • CSF Radiators
  • Special order items, including sub-parts, hardware, hoses, and fittings

A Few Things to Know

The following are not eligible for return or exchange:

  • Hardware and accessories:  Items must be returned with all hardware, accessories, and equipment included at purchase or a damage fee will be assessed.
  • Original shipping costs:  Outbound shipping fees are not refunded in any case.
  • PayPal payments:  Refunds on PayPal orders will exclude the processing fee assessed by PayPal.

Refund Timeline

Once your return is received and inspected, refunds are issued by check, credit card, or account credit at our discretion. Please allow up to 12–14 working days for a credit card refund to appear on your statement.

 

Did your package arrive damaged or missing parts?

Shortage and damage claims must be made within 5 working days of the receipt date. All claims for damaged merchandise must be made with the carrier. Keep all shipping cartons and packing materials for carrier inspection. ASMC LTD. will not initiate any claims with the carrier. All approved refunds will be paid by either check, credit card, or account credit, to be determined by ASMC LTD.

Close-up of worn engine cylinder heads with carbon deposits

Reduce Carbon Buildup

Crankcase blow-by, made up of oil particles and air, is recirculated into the intake. The PERRIN Air Oil Separator captures the oil before it reaches the intake tract, which helps limit carbon buildup in the valves and combustion chamber. Reducing this buildup helps avoid power loss and lowers wear and tear on the valves.

PERRIN Air Oil Separator internal swirl pot design showing oil separation technology.

Advanced Airflow Separation

The PERRIN Air Oil Separator uses two internal airflow methods to remove oil from blow-by. The swirling airflow pulls oil particles out of the air, and the internal grooves, curves, turns, and holes create impact points that catch additional oil for efficient separation.

PERRIN red Air Oil Separator installed in 2002-2021 Subaru WRX/STI engine bay.

Optimized Placement

The 2002-2021 WRX/STI AOS places the unit in an ideal location to maintain proper operating temperature and keeps the AOS clear of strut bars, master cylinder braces, and cold air intakes.

Explain like I'm 5

The PERRIN Air Oil Separator isn’t like a catch can. A catch can is like a little cup that fills up with yucky engine stuff, and you have to empty it all the time. An Air Oil Separator is smarter, it separates the oil from the air and sends the oil back into the engine, so you don’t have to keep checking and draining it.

PERRIN Air Oil Separator coolant heating system with integrated hose connections.

Warmed for Proper Vapor Separation

Coolant heats both the top and bottom of the PERRIN AOS, keeping the body at the same temperature as incoming blow-by. This reduces condensation, prevents sludge buildup, and helps oil, air, and water vapor separate. 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.

Serviceable by Design

The PERRIN AOS is virtually maintenance free but can be opened with a single bolt when cleaning is needed. This simple design gives quick access to the internal surfaces so any residue can be wiped out easily.

Oil residue on top-mount intercooler showing need for PERRIN Air Oil Separator.

Intercooler Efficiency

Keeping oil out of the intake and intercooler is essential for maintaining efficient heat transfer. Oil buildup inside the intercooler reduces its ability to dissipate heat effectively, leading to higher intake air temperatures (IAT).

Oil Vapor Costs You Power

Preventing oil from entering the combustion chamber is critical for maintaining engine performance. When oil enters the chamber, it lowers the effective octane rating of the fuel mixture, which can reduce horsepower and increase the risk of detonation.

PERRIN Air Oil Separator precision CNC machined billet aluminum construction.

In-House Machining, Superior Durability

All major components of the PERRIN Air Oil Separator are CNC machined in-house from 6061-T6 aluminum for superior durability and long lasting performance.

PERRIN Air Oil Separator showing black anodized finish and billet aluminum construction

Ceramic Coated for Maximum Durability

The PERRIN Air Oil Separator features a ceramic coated finish rated for more than 500°F. Harder than powder coat, the finish is scratch resistant, extremely durable, and acts as a thermal barrier that helps retain heat in the AOS to reduce moisture buildup that can lead to sludge. It also provides strong chemical resistance, so engine oil, blow-by, and other chemicals will not affect the finish.

PERRIN Air Oil Separator fittings and hose connections for easy installation

Custom Crankcase Fitting

The EJ AOS features a purpose-built crankcase fitting rather than a universal adapter. The threaded drain fitting accepts a wide range of fittings, which makes it easy to customize for special projects and unique setups.

Two Clamp Styles Included

Each PERRIN AOS includes two styles of stainless steel hose clamps. Choose between low profile or screw drive clamps to match your preference. Unlike standard clamps, these stainless steel options resist rust and are built to last the life of your vehicle.

Durable Aluminum Connectors, Not Plastic

All PERRIN AOS hose attachment points use CNC machined aluminum fittings. Unlike plastic fittings, they will not snap during installation or fail over time. Each fitting is machined in house and anodized for corrosion resistance and long term durability.