Description
The PERRIN Air Oil Separator (AOS) for 2002–2014 Subaru WRX, WRX STI, Legacy GT, and Outback XT applications is designed for vehicles equipped with a front-mount intercooler (FMIC). It improves engine reliability and performance by removing oil vapors from crankcase blow-by before they reach the intake system.
Built for Subaru EJ-series turbocharged engines, this system helps reduce carbon buildup on intake valves, protect intercoolers, and maintain consistent engine efficiency under high-performance conditions.
Unlike traditional catch cans that require regular emptying, the PERRIN AOS operates as a closed-loop system that captures oil from crankcase gases and returns it directly to the engine. This eliminates routine maintenance while ensuring cleaner intake airflow.
The system uses advanced internal airflow separation technology, combining a swirling oil separation process with engineered internal impact surfaces. These features work together to efficiently extract oil from air and vapor mixtures, reducing contamination in the intake tract, intercooler, and combustion chamber.
A key feature of this application is its compatibility with FMIC setups, ensuring proper routing and fitment in modified engine bays commonly used for performance builds.
Constructed from CNC-machined 6061-T6 aluminum and finished with a high-temperature ceramic coating rated over 500°F, the system is built for durability, heat resistance, and long-term reliability. Aluminum fittings and stainless-steel hardware provide a secure and precise installation.
FITMENT:
2002–2014 Subaru WRX (EJ engines, FMIC only)
2004–2021 Subaru WRX STI (EJ engines, FMIC only)
2005–2009 Subaru Legacy GT (EJ engines, FMIC only)
2005–2009 Subaru Outback XT (EJ engines, FMIC only)
Key Features:
Removes oil vapors from crankcase blow-by
Reduces carbon buildup on intake valves
Improves engine performance and longevity
Closed-loop oil return system (no draining required)
Advanced internal air/oil separation technology
Designed for FMIC-equipped vehicles
CNC-machined 6061-T6 aluminum construction
High-temp ceramic coated finish (>500°F rated)
Direct-fit installation with application-specific mounting
Includes mounting bracket and installation hardware
Specifications:
Application: Subaru WRX / STI / Legacy GT / Outback XT (2002–2014, FMIC only)
Engine: EJ-series turbocharged engines (EJ205 / EJ255 / EJ257)
Material: CNC-machined 6061-T6 aluminum
Finish: High-temperature ceramic coating
System Type: Air Oil Separator (closed-loop oil return)
Installation: Bolt-on, FMIC-compatible application-specific kit
