Radium Engineering 2015+ Subaru WRX Air Oil Separator Kit (INCLUDES 20-0255)

The Radium Engineering Air Oil Separator Kit for the 2015-2021 Subaru WRX and 2014-2018 Forester XT is designed for FA20F-powered vehicles that generate more crankcase blow-by than a conventional catch can may comfortably handle. Instead of storing collected oil for periodic draining, Radiums AOS-R system separates oil from the crankcase vapors and routes it back into the engine, creating a low-maintenance closed-loop system.

The separator is coolant-heated to help control condensation, and an integrated water trap keeps collected moisture from draining back into the engine oil. Vapors are routed back to the turbo inlet, keeping the system sealed while helping reduce oil contamination inside the intake tract, turbocharger, intercooler, throttle body, and intake manifold.

This kit installs near the brake master cylinder and includes the Radium brake master cylinder brace required to mount the AOS-R. Radium lists the kit for left-hand-drive 2015-2021 Subaru WRX and 2014-2018 Subaru Forester XT models. It is not the correct AOS-R kit for the WRX STI or 2022+ WRX.