Radium AOS-R Air Oil Separator for 2015+ WRX Radium

An AOS (Air Oil Separator) kit is responsible for keeping blow-by oil and other pollutants out of the intake pipe, manifold, turbocharger, and intercooler during all engine loads. The AOS-“R” system “returns” what is collected back into the oil pan so there is no servicing required. The AOS mounts to the Radium Brake Master Cylinder Brace. The AOS is available with or without the brace in case you have already purchased it.

Vehicle Fitment:
• 2015+ Subaru WRX (FA20F)
(* Fits LHD / Left Hand Drive ONLY *)

Required for Install:
Master Cylinder Brace
(Available with the AOS Kit if you don’t already have it.)

Install Notes:
• The Radium AOS-R kit may not be compatible with all other aftermarket products.

Install Instructions:
Download PDF

WRX Install Notes:
The Radium Engineering AOS kit installs on the LH side of the engine bay, near the brake master cylinder. The outlet (side port) of the AOS is plumbed back to the turbo inlet pipe, creating a completely sealed system.

The AOS mounts to the Radium Brake Master Cylinder Brace, as shown below. This brace is REQUIRED for installation. The kit is available with or without the brace in case you have already purchased the brace.

The PCV valve is replaced by a custom machined straight-through adapter fitting. Oil collected in the AOS drains out the bottom fitting and back into the engine block through this fitting.

More Information:
High-powered modified Subaru engines tend 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 Subaru Dual Catch Can Kit, the AOS (Air Oil Separator) kit is responsible for keeping blow-by oil and other pollutants out of the intake pipe, manifold, turbocharger, and intercooler during all engine loads. The main difference is that an AOS-“R” system “returns” what is collected back into the oil pan so there is no servicing required.

The built-in heater keeps water from condensing in the AOS, and because water is more dense than oil, there is an integrated water trap found around the bottom perimeter of the can. This prevents water from descending into the oil pan if ever present.

Furthermore, because the water is trapped against the heater, it will eventually boil and evaporate out of the system.

The direct-injected Subaru FA20F engine in particular has an inherent problem since there are no port injectors to clean the backside of the intake valves.

The AOS is constructed of CNC machined sections that screw together and are sealed with O-rings. The AOS can be completely disassembled for cleaning or servicing.

Benefits:
• Effectively raises the fuel 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.

Includes:
• Machined aluminum Radium Engineering Air/Oil Separator
• Specially designed mounting bracket
• All necessary SAE J30R7 rated PCV/Emissions hose
• Coolant hoses and fittings
• PCV delete fitting
• All necessary aluminum fittings and hose-ends
• Stainless steel mounting hardware
• 20-0255 Master Cylinder Brace (Optional)

Measurements:
• AOS Height: 6.94″ (top of dipstick to bottom of AOS)
• AOS Diameter: 3.45″ Round
• AOS Capacity: 20.3 oz (600mL)

Note for Cold Climates:
For users in extremely cold climates, Radium Engineering recommends installing insulation sleeving (not included) over the PCV hose near the turbo inlet. This will help prevent the natural phenomenon of water condensation freezing and potentially clogging the hose. This can be a problem if the vehicle starts in a freezing environment and drives a short distance.