This part is legal for sale and use on Emissions Controlled Vehicles in all 50 states when used in accordance with the manufacturer's application guide because it has a California Air Resources Board (CARB) Executive Order (EO) number:
The COBB Air/Oil Separator is placed within your Subarus crankcase ventilation system and helps to prevent oil vapors from being introduced into the intake system. The COBB Air Oil Separator has been developed in partnership with IAG Performance and offers exclusive features.
- 1 Liter Holding Capacity
- Integrated ORB Ports
- Compact Cast Aluminum Body w/ Black Powdercoat Finish
- Heat Shielding on Crankcase Breather and Oil Return Lines
- Coolant Bleeder Valve
- Bespoke COBB Color Combination
- Laser Etched COBB Logo
The Subaru EJ engine has 3 ports that vent crank pressure: one on each cylinder head and another on the top of the block. Each engine vent port receives its own connection to the AOS. By giving each engine port its own entrance to the AOS we have allowed for more effective and faster excavation of crankcase pressure. Additionally, this reduces overall system pressure. With a 4" OD and 5.75" height, the AOS has an approximate 1 liter of holding capacity. The larger the AOS, the more power you can safely make without having to worry about the AOS overfilling.
The bottom of the AOS is shaped like a snail, redirecting positive crank pressure into the same swirl pattern produced by the 3 side ports. Allowing maximum oil drainage while separating oil from the air in all the venting ports.
The back plate of the AOS features a unique coolant routing system that heats the entire AOS to the same temperature of the engine. This maximizes the evaporation of any water collecting inside of the can. The hotter the AOS, the less water will collect inside and mix with the oil.
The COBB Subaru Air/Oil Separator helps to prevent crankcase oil vapors from recirculating back through your engine's intake system.
Oil vapors passing through your engine's intake system lower the effective octane rating of fuel and can contribute to both oil and carbon buildup over time.
- Compact Cast Aluminum Tank Design
- Bespoke COBB Anodizing on Caps
- Wrinkle Black Powder Coated Canister
- Laser Etched COBB Logo
- Developed in Partnership with IAG Performance
09-13 Subaru Forester XT 2.5 EJ255
05-09 Subaru Legacy GT 2.5 Turbo EJ255
08-14 Subaru Impreza WRX STI 2.5 Turbo EJ257
15-21 Subaru WRX STI 2.5 Turbo EJ257
08-14 Subaru Impreza WRX 2.5 Turbo EJ255
Payment & Security
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.