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IAG Air / Oil Separator (AOS) Fits 2015-21 Subaru Impreza WRX

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IAG Air / Oil Separator (AOS) Fits 2015-21 Subaru Impreza WRX


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IAG Air / Oil Separator (AOS) Fits 2015-21 Subaru Impreza WRX

IAG Air / Oil Separator (AOS) Fits 2015-21 Subaru Impreza WRX


IAG Air / Oil Separator (AOS) Fits 2015-21 Subaru Impreza WRX

  • IAG Performance Air / Oil Separator (AOS) Street to Competition Series Conversion Kit For 2015-21 WRX
  • IAG Multi-Directional Hose Clamp Pliers


IAG Air / Oil Separator (AOS) fits 2015-21 SUBARU Impreza WRX


The IAG Air / Oil Separator (AOS) is a smart investment to safeguard and improve your Subaru's performance. Developed over years of rigorous testing on various standard and competitive applications, the IAG AOS provides unmatched protection for your 2015-2021 Impreza WRX engine. Our exclusive AOS design incorporates a 1-liter cast aluminum swirl pot canister that significantly improves oil separation from the PCV system before returning PCV gasses to the intake. The durable and lightweight aluminum housing provides improved ventilation, while incorporating the use of an intelligent baffle design that sets it apart from the competition. It works with all fuel types, prolongs engine lifespan, enhances crankcase ventilation, and seamlessly integrates with standard ECU settings.


Oil in the engine's intake tract may lead to various negative effects. Preventing oil from entering the engine intake is vital to prevent premature mechanical issues and to uphold optimal performance in your Subaru. Oil coated components in the intake, intercooler and plumbing can lead to the breakdown of the rubber and silicone hose connections. Once the oil enters the intake tract, the oil can access the intake manifold and then the engine’s combustion chamber, potentially triggering detonation, pre-ignition, excessive emissions, smoke, power loss, reduced fuel efficiency, and even engine damage or complete engine failure.

Oil in intake tract


Unlike ordinary catch-can systems, the IAG Air / Oil Separator functions without the need for routine draining or maintenance. The separated oil gathers along the walls of the AOS canister, then drains gradually into the engine's crankcase. The large body of the IAG AOS eliminates the risk of overflow by allowing the oil to drain slowly, whereas smaller catch cans are unable to keep up and often require manual draining. The exclusive heating system on the IAG AOS ensures that the gathered oil remains free of sludge, reducing the possibility of reintroducing it back into the engine.


The IAG Air / Oil Separator uses a unique baffle system to collect and drain the oil from your engine's PCV gasses back to the crankcase. The AOS body's inlet hoses create an internal gas vortex, which then filters through the baffles, trapping the oil and allowing the gas to escape from the top of the AOS canister. Because the OEM PCV remains functional, the engine is also able to provide additional vacuum, which helps to remove more of the PCV gasses.

Air / Oil Separator Inside and Function
Improved PCV Check Valve


The IAG Air / Oil Separator works alongside the OEM PCV system, while increasing its capacity. It assists the PCV gasses to the turbo inlet using a new, upgraded PCV check valve that provides extra suction and air-oil separation. In ethanol-fueled applications, it prevents oil dilution and lubrication issues by capturing fuel vapors from the oil and reintroducing them for combustion. IAG’s AOS prevents oil from entering the intake and oil dilution in the engine's lubrication system, going beyond the capabilities of the OEM PCV system alone.


Crafted with a lightweight yet sturdy aluminum housing, the IAG Air / Oil Separator is even lighter than our previous AOS iterations. Whether you're drag racing or hitting the track in your Subaru, we value the importance of weight savings. This is why we've fine-tuned and lightened this AOS design to enhance your Subaru's overall performance, guaranteeing you get the best results every time you race or hit the track.

Lightweight Design


The IAG Air / Oil Separator features a proprietary heating system that capably handles issues frequently encountered in lower-quality catch cans. Unlike inferior designs that allow hot PCV gasses to pass through cold passages, leading to condensation mixing with oil and causing sludge, IAG's improved design is linked to the vehicle's cooling system. This enables the transfer of heat from the engine into the AOS canister. By heating the AOS canister to the engine's temperature, condensation and associated buildup are significantly diminished or completely eliminated.


IAG's Air / Oil Separator comes with a complete set of custom-length SAE Quick Connection lines, simplifying the installation process and minimizing the risk of leakage as a result of a more dependable and secure connection compared to standard hose clamps. Once installed, our AOS system features a polished factory-like appearance that matches your Subaru’s engine.

SAE Quick Connection Lines
Easy to Install AOS


Our engineers set out to make the system as easy to install as possible for the 2015-2021 Impreza WRX. 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 IAG Air / Oil Separator also includes pre-cut and crimped hoses on applicable Subaru models. The IAG AOS is available in your choice of black, red or neon yellow to perfectly accentuate the engine bay of your Subaru.

What's Inside:

  • Product Name: IAG Air / Oil Separator (AOS) Fits 2015-2021 Subaru Impreza WRX
  • Part Number: IAG-ENG-7187
  • Material: Cast Aluminum
  • Color: Black, Red, Neon Yellow
  • Package Includes: 1x Air / Oil Separator, 1x Hose And Fitting Kit, 1x Mounting Bracket
  • Fitment: 2015-2021 Subaru Impreza WRX

Installation Instructions:

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Model Year & Fitment

  • 2015 Subaru WRX
  • 2016 Subaru WRX
  • 2017 Subaru WRX
  • 2018 Subaru WRX
  • 2019 Subaru WRX
  • 2020 Subaru WRX
  • 2021 Subaru WRX


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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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