Protect Your Intercooler & Engine

The Perrin Air Oil Separator (AOS) increases intercooler efficiency by reducing the amount of oil deposited into your intercooler and intake system. As blow-by and oil build up inside your intercooler, heat transfer efficiency drops — leading to power loss and potential detonation that can damage your engine.

Reduce Carbon Buildup

Crankcase blow-by is recirculated back into the intake, depositing oil and carbon throughout the intake tract, intake valves, and intercooler. Over time this causes measurable power loss and accelerated valve train wear. The Perrin AOS intercepts this contamination before it reaches your engine.

Coolant-Heated Base Plate

The AOS base plate is heated by coolant drawn directly from the engine, keeping the unit at operating temperature. This minimizes water condensation and allows oil and water vapor to separate cleanly as they pass through the can.

Low Maintenance Design

The coolant-heated design virtually eliminates sludge buildup inside the AOS body — dramatically reducing how often you need to clean it compared to unheated units.

Fitment: 2002–2014 Subaru WRX | 2004–2021 Subaru STI | 2005–2009 Subaru Legacy GT

Part Number: PSP-ENG-607NY

Prop 65 Warning

⚠️ This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.