GrimmSpeed Air Oil Separator

Part #: GRM 078006
MSRP: $314.99
( 37 reviews )



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This product is covered by our
RallySport Guarantee
No questions asked 30 day return policy


Brand: Grimmspeed
Color: Black
Installation Hardware Included: Yes
Material: Aluminum
Mfgr. Warranty: 2 years
Return Policy:

RallySport Guarantee - 30 Days

Items that are covered under the RallySport Guarantee offer a 30 day no questions asked return policy.

RallySport Guarantee items may be returned within 30 days of the original invoice date and must include all the original parts and contents for a refund.

The RallySport Guarantee does not apply to products that have been modified, damaged, misused or abused. All returns require an RMA (Return Merchandise Authorization) Number, and freight charges are strictly non-refundable. For more information regarding our freight refund policy, please refer to our return policy page found HERE.
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Subaru Impreza
WRX STI 2004, 2005, 2006, 2007WRX STI Limited 2007WRX STI Hatchback 2008, 2009, 2010, 2011, 2012, 2013, 2014WRX STI Special Edition Hatchback 2010WRX STI Limited Sedan 2011, 2012, 2013, 2014WRX STI Limited Hatchback 2011, 2012, 2013, 2014WRX STI Sedan 2011, 2012, 2013, 2014WRX 2002, 2003, 2004, 2005, 2006, 2007WRX TR 2006, 2007WRX Limited 2006, 2007
Subaru Forester
XT 2004, 2005XT Premium 2005XT Limited 2006, 2007, 2008Sports 2.5 XT 2008
Subaru WRX STI
Base 2015

An Air/Oil (AOS) 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 AOS has a unique patent pending design that allows you to maintain your PCV Valve while separating the oil out of the crankcase and head ventilation air!

Removing oil out of your intake system will result in a more efficient engine. An Air Oil Separator takes the place of an oil catch can or tank, resulting in you not having to empty your oil catch can. As well as being very subtle and not noticeable.

Another benefit to this unique design is the compact and clean look; making this ideal for someone who wants to keep it looking stock under the hood.

REVIEWS ( 37 )



Looks good
derekbutler9402075 8 months ago
Bought mine off the Grimmspeed website. It was under the Garage Sale section for $179. It's mixed colors but I don't really care because you never see it anyway. Honestly, it was a PITA to install. That's only cause I live in Maine and decided to install it on a 30 degree day and all the lines were very stiff so the half to half connectors were very difficult to put in. It does look great though. Especially after zip tying the hoses together. Which reminds me, the zip ties that come with this are crap, every single one of them broke on me. Went to the hardware store and picked up a pack of heavy duty 7 ties for about $5.

Great fitment and quality
watervilleimport03344 1 year ago
install was very easy, i even went a step further and routed almost all of the hoses underneath the manifold so you barely even notice its aftermarket. very happy with product, also noticed that there is no oil in the intercooler after running it

Great fitment and quality
watervilleimport03344 1 year ago
install was very easy, i even went a step further and routed almost all of the hoses underneath the manifold so you barely even notice its aftermarket. very happy with product, also noticed that there is no oil in the intercooler after running it
Verified Purchase
polzin.rich40086 1 year ago
For my car at least, definitely a great purchase. Idle is much smoother and the engine feels/sounds healthier. There's a big debate about the necessity of running an AOS, but I'd say its worthwhile. Install was easy, although beware if you have an older model as your hoses might be stiff, making the coupler near impossible to fit into, even with a bit of oil. An easy fix is to just use the supplied hose as replacement for the factory pieces.
Verified Purchase
Great Product
Infamous 1 year ago
theres an old saying all subarus leak oil and its usual... i was sick of the saying and got one of these. its so resourceful i swear it cleans and helps the motor. i didnt have to add oil anymore or worry about any getting in the intake causing blow by .... great product better than a catch can


  • AnswerQ: Fitment  dmonti11739951 5 months ago

    Someone is selling one of these off of a 2012 wrx, why will a 2012 STI confirm fitment but not a 2012 wrx? It is just the part that screws in and i am wondering if its just that particular part will it work?! :)

    • A: The 2008-2014 WRX models have a very different setup when it comes to induction and ventilation, it may be adaptable but this is not a direct fit and purchasing the correct AOS for your vehicle is recommended for ease of install.

      Nick S. 5 months ago

  • AnswerQ: Install video valid on 15 STI?  wongchonghing85258 6 months ago

    Was curious if the install video applies for the 2015 STI? All step and procedures are the same in the video for installation on 2015 STI?

    • A: The install should still be the same on your car.

      Josh P. 6 months ago

  • AnswerQ: Stiff hoses?  JeyMT 8 months ago

    I've evaluated my hoses in my 04 STi. They are quite stiff and hard to remove and prone to breaking. Will the provided hose from this kit be enough to replace the hoses accordingly while still having enough to connect to the AOS piece? It's 8 feet of hoses correct? Thank you!

    • A: There is 8.5 Feet of hose included and should be enough to replace the old lines that are stiff.

      8 months ago

  • AnswerQ: Power Rating  sikknt 12 months ago

    Does this still work if you're running 400hp?

    • A: This will still work with no issues.

      Kyle A. 12 months ago

    • A: Horsepower shouldn't be a limiting factor as long as your engine is running healthy and has no more than factory amounts of blow by. Mike

      sales559bb8b6bb86418e5b8c258d 11 months ago

  • AnswerQ: does it fit a 08+ wrx or only sti?  nicatlotus63359 1 year ago

    Will it fit my 2013 wrx or sti only?

    • A: We have a different part for the WRX Mike

      sales559bb8b6bb86418e5b8c258d 1 year ago

    • A: Unfortunately this one is not made for those years of WRX's however, here is the Grimmspeed AOS that you would need:

      Spencer H. 1 year ago