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.
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: D-660-25 D-660-45