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1 (800) 821-KAMI (USA)

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GrimmSpeed Air Oil Seperator 02+ Subaru WRX STi

GrimmSpeed (AOS) Air/Oil Separator - 02-07 Impreza WRX, 04-14 Impreza WRX STI, and 15+ WRX STI

Regular price $295.00 USD $295.00 USD Sale

Availability: In Stock Sold Out

Manufacturer: GrimmSpeed

SKU: grm078008


The Grimmspeed AOS (Air Oil Seperator) is a compact upgrade that does the job of combating the factory's blow-by problem; this is a common problem in Subaru EJ25 motors and can cause the dreaded ring land issue.

Most systems implement a complex and cumbersome system with an actual oil catch tank, the Grimmspeed system is a much simpler inline kit that replaces the oil cap*. This kit basically keeps oil away from the engine's ventilation system, this way you'll have a cleaner air intake system without oil going through it.

As a result, you will experience the following:
  1. Consistent oil octane
  2. Reduced chances of engine knock (detonation)
  3. Reduced oil consumption
  4. Cleaner emissions and MPG

  • Subaru Impreza WRX [GD/GG] (2002, 2003, 2004, 2005, 2006, 2007)
  • Subaru Impreza WRX STi [GDB] (2004, 2005, 2006, 2007
  • Subaru Impreza WRX STi [GRB/GVB] (2008, 2009, 2010, 2011, 2012, 2013, 2014)
  • Subaru WRX STI [VAB] (2015, 2016, 2017, 2018)
*Recommended for OEM, Stage 1, or Stage 2 builds. For Stage 3 and High Horse power builds a AOS with catch tank is recommended


Compact system
Helps ensure engine longevity
Ideal for OEM, Stage 1, and Stage 2 builds
Available in 3 finishes
Made of Anodized Aluminum for looks and endurance
A must have for all EJ25 Turbo Motors

Extended Information

Type: Air Oil Separator
Catch Tank: Not included
Design: In line with PCV system
Finish: Black, Blue, or Red
Material: Aluminum

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Return Policy

Returns Policy

Most items may be returned within 30 days of the product arriving to your house or place of work.
Returns will NOT be accepted on special order, opened, installed, incomplete, or otherwise used products.

In order to initiate a return, an RMA number must be requested and approved. All returns will be subject to a 15% restocking fee minus complete shipping cost.
For complete details on our return policy, please see our Help and FAQ link under HELPFUL INFO.