Radium Engineering 2015+ Subaru WRX Air Oil Separator Kit (INCLUDES 20-0255), 20-0258-00

A high powered modified engine tends to generate excessive blow-by oil and gasses. In these cases, an ordinary small catch can may quickly fill with oil and not be adequate. Like the Radium Engineering Catch Cans, the AOS (Air Oil Separator) kit is responsible for keeping blow-by oil and other pollutants out of the air intake and intercooler (if equipped) systems. The main difference is that an AOS system returns collected oil back into the oil pan so there is no servicing required.

IMPORTANT INSTALLATION NOTES:

In order for the AOS to function properly, a port must be supplied on the engine for the oil to return through.

The AOS must be mounted high enough in the engine bay so that the port on the bottom is higher than the oil return port on the engine.

Engine coolant must be available to be routed to AOS in order facilitate heating it so that it functions correctly.

Without a properly designed AOS, water condensation can develop and find its way in the oil pan contaminating engine oil. Engine coolant lines are routed through the Radium Engineering AOS in a specially designed heating chamber. This keeps the AOS warm and prevents water from condensing inside.

For AOS crankcase plumbing, the valve cover vent(s) are routed into the top inlet where the stainless steel condensing material separates the oil from the gasses. The filtered liquid oil is collected at the bottom of the AOS and drawn into the oil pan. Meanwhile, the clean crankcase air can either be vented to atmosphere (VTA) or recirculated to the turbo air inlet pipe.

With a properly operating system, the fluid level inside the AOS will be empty after sitting. If there is a possible return obstruction, simply unscrew the anodized billet aluminum dipstick for inspection. Conversely, the entire billet unit disassembles into 3 large pieces for servicing.

Benefits

Effectively raises the octane and increases engine performance with cleaner inlet air

Prevents oil buildup in the intake or intercooler system walls, throttle body, intake manifold, etc.

Lowers hydrocarbon emissions

Included

Machined alumium Radium Engineering AOS

Anodized universal mount that permits 360deg rotation

Two 5/16" barbed fittings for coolant lines

Stainless steel hardware

Ports

Top Port: 7/8"-14 threaded for 10AN ORB fittings

Side Port: 7/8"-14 threaded for 10AN ORB fittings

Bottom Port: 7/8"-14 threaded for 10AN ORB fittings

Coolant Ports: 7/16"-20 threaded, includes two 5/16" barb fittings

Measurements

AOS Height: 6.94" (top of dipstick to bottom of AOS)

AOS Diameter: 3.45" Round

AOS Capacity: 20.3 oz (600mL)

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