PERRIN Air Oil Separator - Black - 22-25 Subaru WRX

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.

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.

The 2022+ WRX AOS uses a bottom plate designed specifically for this application. It places the unit in an ideal location, maintains proper operating temperature, and keeps the AOS clear of aftermarket intercoolers, charge pipes, master cylinder braces, and cold air intakes.

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.

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.

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.

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)

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

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.

The PERRIN Air Oil Separator is ceramic-coated inside and out with a finish rated for more than 500°F. This coating is harder than powder coat, scratch-resistant, and extremely durable. It offers strong chemical resistance, so engine oil, blow by, and other common chemicals will not affect the finish.

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.

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.