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IAG Air / Oil Separator (AOS) For 2008-14 Subaru WRX & 2008-21 STI

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IAG Performance

IAG Air / Oil Separator (AOS) For 2008-14 Subaru WRX & 2008-21 STI


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IAG Air / Oil Separator (AOS) For 2008-14 Subaru WRX & 2008-21 STI

IAG Air / Oil Separator (AOS) For 2008-14 Subaru WRX & 2008-21 STI


IAG Air / Oil Separator (AOS) For 2008-14 Subaru WRX & 2008-21 STI

  • IAG Performance Air / Oil Separator (AOS) Street to Competition Series Conversion Kit For 06-14 WRX, 04-21 STI
  • IAG Multi-Directional Hose Clamp Pliers


IAG Air / Oil Separator (AOS) fits 2008-14 SUBARU Impreza WRX & 2008-21 STI


The IAG Performance Air / Oil Separator (AOS) is a valuable investment to protect and maintain peak performance in your Subaru. Developed through years of meticulous testing on standard and competitive applications, the design of the AOS offers unparalleled protection for your engine. This AOS features a 1-liter swirl pot canister made of cast aluminum. This construction significantly enhances the separation of oil from the PCV system before the PCV gasses are directed back to the intake system.The Air Oil Separator features an aluminum housing that has superior ventilation, and it incorporates an exclusive baffle design that sets it apart from the competition. It works with all fuel types, prolongs engine lifespan, optimizes crankcase ventilation, and seamlessly integrates with standard ECU settings, so no tuning is required.


The presence of oil within the engine's intake tract brings about a range of adverse effects, so preventing oil from entering the engine intake is crucial for avoiding premature mechanical issues and maintaining optimal performance. Initially, the oil coats the internal components of the intake, intercooler, and piping, which can potentially harm or prematurely deteriorate rubber or silicone hoses, eventually leading to compromised connections. Once the oil enters the intake tract, it has access to the intake manifold and then the engine’s combustion chamber. Oil inside the chamber has the potential to trigger detonation, pre-ignition, excessive emissions, smoke generation, power loss, reduced fuel efficiency, and in extreme cases, severe engine damage or even complete engine failure.

Oil in the intake tract


The IAG AOS is designed for effortless upkeep. Unlike typical catch-can systems, our Air Oil Separators operate without the need for routine draining and maintenance. Separated oil gathers on AOS can walls and slowly drains into the engine's crankcase. With the help of our unique heating system, the collected oil remains free of sludge, ensuring that there is no risk of reintroducing it into the engine. The substantial size of the AOS body allows for a safe and gradual oil drainage process, effectively removing the chance of overflow commonly observed in smaller catch cans.


The IAG Air / Oil Separator features a unique baffle system that captures the oil suspended in your engine's PCV gasses, which are then able to drain back into the crankcase. The AOS body's inlet hoses are set up to create an internal gas vortex, which is then filtered through a series of baffles. The baffles gather the oil while enabling the gasses to exit from the upper part of the AOS canister. As the factory PCV remains active, this allows the engine to generate a vacuum in the AOS assembly to draw out even more of the PVC gasses.

What's Inside and AOS
AOS Improves the PCV System


The AOS works with the OEM PCV system, while also providing a boost to its capacity. The AOS directs PCV gasses to the turbo inlet, using an upgraded PCV valve for additional suction and air-oil separation. For applications using ethanol fuel, the AOS provides protection against problems like oil dilution and lubrication issues. This is accomplished by capturing fuel vapors emitted from the oil and then reintroducing them into the intake tract for combustion. The AOS provides exceptional protection against oil entering the intake flow and oil dilution in the engine's lubrication system, exceeding the capabilities of the OEM PCV system alone.


The IAG Air / Oil Separator uses a unique heating system to solve problems found in lesser catch cans. In inferior models, hot PCV gasses pass through a cold pathway, which causes condensation that mixes with the oil and causes sludge. IAG’s upgraded design attaches to the vehicle’s cooling system, allowing heat from the engine to transfer into the AOS canister. By warming the AOS canister to the engine's temperature, condensation and related buildup are greatly reduced or eliminated.

IAG Air / Oil Separator (AOS) for the 08-14 WRX & 08-21 STI


Our engineers set out to make the system as easy to install as possible for the 2008-14 Subaru Impreza WRX & 2008-21 STI. The connection hoses at the canister are custom fitted SAE Quick Connection lines that are the exact length to reach the corresponding engine parts. The AOS is available in your choice of black, red or neon yellow to accent the engine bay of your Subaru.


IAG’s Air / Oil Separator includes a full set of custom length SAE Quick Connection lines that not only simplify the installation of the AOS system, but they also reduce the chance of leakage because they offer a more reliable and secure connection than basic hose clamps. Once installed, our AOS system has a clean, factory-look that integrates seamlessly with your Subaru’s engine.

AOS Quick Connection Lines

What's Inside:

  • Product Name: IAG Air / Oil Separator (AOS) For 2008-14 WRX, 2008-21 STI, 2005-09 LGT
  • Part Number: IAG-ENG-7186BK, IAG-ENG-7186RD, IAG-ENG-7186NY
  • Material: Cast Aluminum
  • Color: Black, Red, Neon Yellow
  • Package Includes: 1x Air / Oil Separator, 1x SAE Quick Connect Hose And Fitting Kit, 1x Mounting Bracket.
  • Fitment: 2008-14 Subaru Impreza WRX, 2008-21 STI, 2005-09 Legacy GT

Model Year & Fitment

  • 2008 Subaru WRX
  • 2009 Subaru WRX
  • 2010 Subaru WRX
  • 2011 Subaru WRX
  • 2012 Subaru WRX
  • 2013 Subaru WRX
  • 2014 Subaru WRX
  • 2008 Subaru STI
  • 2009 Subaru STI
  • 2010 Subaru STI
  • 2011 Subaru STI
  • 2012 Subaru STI
  • 2013 Subaru STI
  • 2014 Subaru STI
  • 2015 Subaru STI
  • 2016 Subaru STI
  • 2017 Subaru STI
  • 2018 Subaru STI
  • 2019 Subaru STI
  • 2020 Subaru STI
  • 2021 Subaru STI
  • 2005 Subaru Legacy GT
  • 2006 Subaru Legacy GT
  • 2007 Subaru Legacy GT
  • 2008 Subaru Legacy GT
  • 2009 Subaru Legacy GT

FREE SHIPPING on orders of $250 or more* Simply look for the logo to enjoy free shipping on selected items throughout the store. Oversized packages and freight shipments do not qualify for free shipping. If the items in your order which qualify for 'Free Shipping' total $250 or more, your order ships FREE! Free shipping is only available to the continental United States also referred to as the “lower 48 states”.

Shipping Policy: All products sold on the shopping cart are shipped by UPS or USPS. All packages include shipping insurance in case they are lost or damaged. USPS requires signature confirmation on all insured orders over $200.00. USPS shipping times are estimated and not guaranteed. UPS tracking numbers are automatically generated when a package ships and the number is sent to the email address you provided. If a package contents is damaged during shipping please notify the shipping driver and file a claim with the shipper. You have 14 days to inspect your shipment and contents. After that period of time, IAG is no longer responsible for missing items. You have 30 days to report any damaged or incorrect items, after that period of time IAG is no longer responsible for returns or exchanges. You can contact us by Email or call 410-840-3555 for assistance. *International orders are subject to customs charges, duties or fees. Please check with your local customs office before ordering. IAG is not responsible for international customs charges, duties or brokerage fees.

Drop Shipping: Some items require drop shipping to complete an order. These products are shipped from manufacturer or distributor warehouses across the country. In some cases, this may speed up delivery time. In other cases, it could add 1-3 days to the delivery time. If you have a question regarding an order please contact our sales desk at 410-840-3555.

Order Processing: Orders placed after 3PM EST may not be processed the same day. Order processing may take 24-48 hours. USPS orders placed after 10am EST will ship the following business day if the items are in stock


How do I return an item?

You have 14 days to inspect your shipment and contents. After that period, IAG is no longer responsible for missing items. You have 30 days to report any damaged or incorrect items, after that period IAG is no longer responsible for returns or exchanges. All stocking products are subject to a 30 Day return policy. The item(s), when approved for return, are subject to a 20 percent restocking fee. Canceled orders may be subject to a 20 percent cancellation fee. All product returns require a return authorization number before being shipped back to IAG or the manufacturer. An “RMA” number is obtained by calling the IAG Support Desk at 410-840-3555 or emailing Some products may require shipping back to the manufacturer for inspection before a return or exchange may be processed. Some products may not be able to be returned. Products that have been modified or installed are not eligible for return. There are no returns or cancellations for Special Order/Made to Order items and Electrical Components (including the COBB Accessport). Items returned after the 30 Day return period without an RMA will be refused. Canceled service appointments with deposits are non-refundable.

Refunds take 30 days or less. Payments made by Credit Card or PayPal are returned back to the original account used during the transaction. There are no cash returns; we will issue a business check for the return of funds. Refunds are decided by the management and not by sales staff. Canceled service appointments with deposits are non-refundable.

IAG Performance Product Warranty (Excluding - Short Blocks / Long Blocks)

This limited warranty gives you specific legal rights and you may also have other rights, which vary from state to state. We limit the duration and remedies of all implied warranties, including, without limitation, the warranties of merchantability and fitness for a particular purpose to the duration of this express limited warranty. Some states do not allow limitations on how long an implied warranty lasts. The remedies described below are your sole and exclusive remedies and our entire liability for any breach of this limited warranty. Our liability shall under no circumstances exceed the actual amount paid by you for the product, nor shall we under any circumstances be liable for any consequential, incidental, special or punitive damages or losses, whether direct or indirect.

This warranty covers defects in materials and workmanship of your IAG Performance Product for 12 Months or 12,000 Miles from the date of receipt.

IAG will repair any IAG Manufactured Product that proves to be defective in materials or workmanship within the warranty period. If a repair is not possible, we will either replace your Product with a new Product of similar composition and price, or refund the full purchase price of your Product, at our sole discretion. There is no charge for inspection but the buyer is responsible for shipping charges.

IAG Performance Engine Warranty

For more information concerning our engine warranty please visit IAG Performance Engine Warranty Page

Other Manufacturer Products:

Products not manufactured by IAG are subject to the individual manufacturer warranties which may apply. If you have questions concerning the fitment, appearance, or performance of your item, please contact a member of our customer support team for assistance.

Our customer service team is happy to assist you with the products purchased from IAG Performance. Our support associates can help you with installation support, troubleshooting advice, and help to identify possible manufacturer defects.

For products that are found to have defects, our support department can provide the contact information for the manufacturer to arrange a warranty inspection and, if applicable, any necessary repairs or replacement shipments.

You may also contact the manufacturer directly for information regarding product eligibility and specific terms and conditions of warranty coverage.

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