2002-2007 Subaru WRX
2004-2021 Subaru STI
2004-2008 Subaru Forester XT
An Air Oil Separator has one job: remove the oil from the engine ventilation system so that the oil doesn't get sent through the intake system. When there is oil in your system, it results in reduced fuel octane, higher chance of engine knock (detonation), worse emissions, and higher oil consumption.
The GrimmSpeed Air/Oil Separator has a unique design that allows you to maintain your PCV Valve while separating the oil out of the crankcase and head ventilation air! This AOS will allow your engine to run more efficiently due to the separation of oil from the intake system. In typical GrimmSpeed fashion, we have made a very compact unit that packs a powerful punch and looks good while doing it. No more having to constantly check or empty your catch can. The GrimmSpeed AOS coalesces oil without using a mesh media as mesh medias can cause contaminants to collect and build up resulting in possible sludge. Our AOS is self maintained so you can just sit back and enjoy driving your car!
- Available in anodized Black or Red finish
- White GrimmSpeed logo
- This unique design utilizes the factory oil filler cap location to maintain your PCV system
- Prevents harmful oil and oil vapors from entering the crankcase and head ventilation system
- Includes all of the required fittings for installation
- Includes a hose that is cut to specific lengths and zip ties
Please note: This product is designed to combat factory amounts of blow by. If you have a built motor or are experiencing abnormal amounts of oil consumption, this product may not work for you.