The IAG Air / Oil Separator (AOS) is a smart upgrade for your Subaru. Developed through years of testing on standard and competitive applications, the IAG Air / Oil Separator offers unparalleled protection for your 2002-2007 Impreza WRX, 2004-2007 STI or 2004-2008 Forester XT engine. Our 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. Constructed from a lightweight, yet durable aluminum housing, the IAG AOS offers improved ventilation and incorporates an intelligent baffle design that sets it apart from the competition. The IAG AOS works with all fuel types, improves crankcase ventilation, and seamlessly integrates with standard ECU settings.

Oil entering the engine's intake tract can result in a range of adverse effects. Preventing oil from entering the engine intake is crucial to prevent premature mechanical problems and to maintain optimal performance in your Subaru. The oil can coat the internal components of the intake, intercooler and plumbing, which can lead to the deterioration of the rubber and silicone hoses, eventually compromising the connections. Once inside 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.

The IAG Air / Oil Separator was designed for ease of use and unlike ordinary catch-can systems, our Air / Oil Separators work without the need for routine draining or maintenance. The separated oil collects along the walls of the AOS can, then drains gradually into the engine's crankcase. The oversized AOS body allows the oil to drain slowly, eliminating the risk of overflow often seen in smaller catch cans. Our exclusive heating system 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 system remains functional, the engine is also able to provide additional vacuum, which helps to remove more of the PCV gasses.

The IAG Air / Oil Separator is constructed from a lightweight, yet durable aluminum housing that is even lighter than any of our previous versions. Whether you drag race or take your Subaru to the track, we know that every little bit of weight counts. This AOS design has been lightened and refined to maximize the overall performance of your Subaru, ensuring you get the most out of every race or track day.

The IAG Air / Oil Separator incorporates the use of its exclusive heating system to eliminate problems found in lesser quality catch cans. Poorly designed versions allow hot PCV gasses to pass through the cold passageway, allowing for condensation to mix with the oil and cause sludge. IAG’s upgraded design attaches to the vehicle’s cooling system, allowing heat from the engine to transfer 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 includes a full set of custom length SAE Quick Connection lines that simplify the installation of the AOS system, as well as 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 polished factory-like appearance that blends seamlessly with your Subaru’s engine.

Our engineers set out to make the system as easy to install as possible. 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.