Skip to content
🌟 Shop The Memorial Day Sale 🌟
🌟 Shop The Memorial Day Sale 🌟

GrimmSpeed Air Oil Separator Black 2002-2007 WRX / 2004-2021 STI / 2004-2008 Forester XT

SKU 078006
Original price $299.00
Original price $299.00 - Original price $299.00
Original price $299.00
Current price $269.10
$269.10 - $269.10
Current price $269.10

An Air/Oil Separator has one job, remove the oil from the engine ventilation system so the oil does not get sent through the intake system.

The GrimmSpeed Air/Oil Separator for turbocharged Subaru models has a unique design that allows you to maintain your PCV Valve while separating the oil out of the crankcase and head ventilation air! Our AOS will allow your engine to run more efficiently due to the separation of oil from the intake system. When there is oil in your system, the result is:

  1. Reduced fuel octane
  2. Higher chance of engine knock (detonation)
  3. Worse emissions
  4. Higher oil consumption.

Our Air/Oil Separator will help all of these problems. 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 check/empty your catch can and refilling your oil. The GrimmSpeed AOS coalesces oil without using a mesh media. Mesh medias can cause contaminates to collect and build up resulting in possible sludge. Our AOS is self maintained so you can just sit back, stop worrying, and enjoy driving your car!

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.


  • Maintenance free design - no more draining your catch can
  • Fully machined billet aluminum construction
  • Durable anodized finish
  • User replaceable O-ring seals


  • 2004-21 Subaru STI
  • 2002-07 Subaru WRX
  • 2004-08 Subaru Forester XT
  • 2004-06 Subaru Baja XT

Customer Reviews

Based on 1 review
J Davis
Easy to install

Super easy to install. The blue matched my WRX well


The simple yet effective design of the GrimmSpeed AOS ensures engine reliability by removing the oil from the engine ventilation so that it does not go back into your intake system! You never have to empty this AOS unlike a catch can and the unique design is slick and clean! We appreciate your 5 Star Review!


Compare products

{"one"=>"Select 2 or 3 items to compare", "other"=>"{{ count }} of 3 items selected"}

Select first item to compare

Select second item to compare

Select third item to compare