Radium Engineering Air Oil Separator Kit | 2002-2007 Subaru WRX STI (20-0207-02)

A built EJ fills a catch can before the oil change; the AOS-R never asks to be emptied.

High-powered modified Subaru engines tend to generate excessive blow-by oil and gasses, and an ordinary small catch can may quickly fill and not be adequate. The Radium Engineering Air Oil Separator (AOS-R) Kit for the 2002-2007 Subaru WRX and STI keeps blow-by oil and pollutants out of the intake pipe, manifold, turbocharger, and intercooler during all engine loads, and 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, the integrated perimeter water trap catches what forms, and the AOS is constructed of three CNC machined sections that screw together and are sealed with O-rings. AOS height is 6.94" (top of dipstick to bottom), diameter 3.45" round, capacity 20.3 oz (600mL).

What You'll Feel

• Set-and-forget crankcase protection on the blow-by-happy EJ, oil returning to the pan automatically
• Effectively higher octane and cleaner inlet air on a knock-sensitive turbo boxer
• The turbo and intercooler protected from the oil film that costs charge cooling
• Oil kept water-free by the coolant heating and perimeter trap
• A chassis-specific bolt-in with everything included

Features

• AOS-R for the 2002-2007 WRX/STI (EJ205/EJ255/EJ257), plus 04-08 Forester XT and 05-06 Saab 9-2X Aero
• Returns collected oil to the pan; no draining required; coolant-heated with perimeter water trap
• 3-piece CNC construction, O-ring sealed; 6.94" H x 3.45" dia; 20.3 oz (600mL) capacity
• Includes machined aluminum AOS, Subaru-specific mounting bracket, all necessary SAE J30R7 rated PCV/emissions hose, coolant hoses and fittings, aluminum fittings and hose-ends, and stainless mounting hardware
• LHD only; lowers hydrocarbon emissions

The Details

Radium's fitment notes deserve the pre-order read: 02-05 Subarus with a cable-actuated throttle body must use Radium's Cruise Control Relocation Bracket; freezing environments call for insulation sleeving (not included) over any hose exposed to cold air flow to prevent condensation freezing and clogging; RHD vehicles must use the Universal AOS-R for custom mounting and plumbing; and the kit may not be compatible with all other aftermarket products. The system runs invisible when healthy, with the fluid level empty after sitting and the dipstick confirming it in seconds. The 08+ chassis use the separate 20-0607.

Kit Includes

• 1x Machined aluminum Radium AOS-R with dipstick
• Subaru-specific mounting bracket; SAE J30R7 PCV/emissions hose
• Coolant hoses and fittings; aluminum fittings and hose-ends; stainless hardware

Applications

• 2002-2007 Subaru Impreza WRX and WRX STI (LHD)
• 2004-2008 Subaru Forester XT; 2005-2006 Saab 9-2X Aero
• 02-05 cable throttle cars require the Cruise Control Relocation Bracket; RHD uses the Universal AOS-R