For Subaru enthusiasts and owners keen on maintaining peak engine performance and longevity, understanding the function and benefits of an Air Oil Separator (AOS) is crucial. Particularly for Subaru vehicles, known for their unique horizontally opposed engine design, an effective oil management system is paramount. The Crawford Performance Air Oil Separator (AOS) stands out as a pioneering solution, specifically engineered to address the oiling system nuances of Subaru engines. While the underlying technology isn’t exclusive to Subaru, Crawford Performance holds the distinction of developing the first AOS system tailored for these vehicles, employing a unique approach not replicated by other aftermarket solutions in the realm of Aos Car Parts.
What Does an AOS Car Part Do?
Imagine an air purifier for your engine’s breathing – that’s essentially the role of an AOS car part. Just as an air filter cleans incoming air, an AOS is designed to meticulously separate oil from the air circulating within your engine. This separation process is vital in preventing oil from being drawn into the intake manifold, which can lead to a myriad of engine performance and durability issues. The AOS ensures that only clean air is recirculated, while the separated oil is returned to the engine, maintaining optimal oil levels and combustion efficiency.
AOS Car Part vs. Catch Can: Understanding the Benefits
When it comes to managing oil in the engine’s ventilation system, two primary solutions are often discussed: the Air Oil Separator (AOS car part) and the catch can. While both aim to prevent oil from entering the intake, their methods and effectiveness differ significantly. An AOS utilizes centrifugal force, skillfully guiding engine oil through a complex internal labyrinth. This intricate system effectively separates oil from engine condensation and blow-by gases. The key advantage of an AOS lies in its self-maintaining operation. The separated, clean oil is automatically drained back into the engine, eliminating the need for manual intervention. It’s a truly install-and-forget solution, offering continuous, maintenance-free protection.
In contrast, a catch can is essentially a collection reservoir. It traps oil and other contaminants but requires manual draining. Furthermore, some catch can setups necessitate pouring the collected oil back into the engine. This process can reintroduce dirty oil and requires regular maintenance. The AOS car part, therefore, presents a more sophisticated and efficient solution by actively separating and recycling clean oil back into the engine, ensuring a cleaner and more sustainable engine environment compared to the passive collection method of a catch can.
Why is an AOS Car Part Essential for Subaru Engines?
Subaru engines, particularly those with a horizontally opposed or “boxer” configuration, are known for experiencing higher-than-average oil consumption. The unique side-to-side movement of pistons in boxer engines, combined with G-forces during driving, can push excess oil towards the top of the pistons. Oil, being combustible, disrupts the controlled combustion process within the cylinders. This irregularity leads to uncontrolled explosions, commonly known as detonation – a serious threat to engine health.
Over time, the accumulation of excess oil intensifies detonation, escalating the risk of engine damage. Detonation is a primary culprit behind “ringland failure,” a term unfortunately familiar to many Subaru owners. This issue is exacerbated in modified, higher-performance Subaru engines. Power-enhancing modifications and increased G-forces from spirited driving further increase the amount of oil entering the intake system. An AOS car part acts as a vital secondary defense system, mitigating detonation risks that are not related to engine tuning issues. By minimizing oil consumption and preventing excess oil buildup, the AOS helps maintain an optimal air-fuel mixture in the cylinders. This, in turn, maximizes engine power output and ensures that your Subaru engine operates efficiently and reliably, freeing you from concerns about avoidable detonation and potential engine damage.
Crawford AOS Car Part: Setting the Standard
Crawford Performance AOS car parts stand out in the market for several compelling reasons, establishing them as a leader in Subaru engine protection:
- The Original Innovator: Crawford Performance pioneered the AOS concept specifically for Subaru vehicles. The current V3 model embodies the latest advancements, featuring patent-pending technology unmatched by competitors.
- Exclusive Dual Chamber Technology: Crawford offers the industry’s only Dual Chamber system in their V3 AOS, and crucially, it achieves this without requiring the removal of any emissions control components, maintaining street legality where applicable.
- Simplified Installation: Designed for efficiency, Crawford AOS kits, particularly the V3, boast significantly faster installation times, often taking half the time compared to other AOS systems on the market.
- Superior Separation Efficiency: The Crawford AOS design uniquely forces oil through an engineered labyrinth system. Each change of direction within this labyrinth enhances the oil separation process, maximizing efficiency.
- Leak-Proof Reliability: Each Crawford AOS canister undergoes rigorous pressure testing post-manufacturing, ensuring exceptional reliability and eliminating concerns about coolant leaks, a potential issue with less robust systems.
Crawford AOS Car Part Versions: V2, V3, and Baja Edition Explained
Crawford Performance has continually refined its AOS car part offerings, resulting in distinct versions tailored to different Subaru models and driving demands:
-
V1 & V2 AOS: The V1, Crawford’s original design developed in 2005 for race vehicles, addressed oil starvation and detonation issues. However, it faced challenges in colder climates due to condensation. The V2 was developed to resolve this with an added coolant bypass line to maintain operating temperature and prevent condensation. It’s important to note that the V2 AOS, by removing the PCV valve, is intended for off-road use only in California and regions with similar emissions regulations.
-
V3 AOS: Representing the pinnacle of Crawford AOS technology for street use, the V3 retains the PCV valve, ensuring emissions compliance. This dual-chamber design utilizes vacuum from the PCV system in one chamber and pressure from the oil system in the other. This innovative approach ensures continuous clean air circulation to the valve covers. Each chamber houses its own labyrinth, further enhancing separation efficiency compared to the V2. The V3 is positioned closer to the engine for optimal heating, eliminating the need for a coolant bypass line and simplifying installation. While incredibly efficient for daily driving, the V3 is not optimized for extreme oil volumes experienced in high-G track racing scenarios.
-
Baja Edition AOS: Launched in 2018, the Baja Edition AOS car part emerged from Crawford Performance’s involvement with Subaru of America’s Crosstrek Desert Racer. Engineered for extreme off-road conditions, this single-chamber AOS, like the V2, uses vacuum from the PCV system but with a simplified two-port design for easy installation. Initially designed for the Crosstrek, the Baja Edition line is expanding to cover more naturally aspirated (NA) Subaru models. It’s ideal for NA Subaru owners seeking robust oil separation in demanding conditions.
Crawford V2 AOS Kit Fitment List by Vehicle
V2 Kit
- 2004 Subaru STI
- 2005 Subaru STI
- 2006 Subaru STI
- 2007 Subaru STI
S0714-1: Designed for Top Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0715-1: Designed for Front Mount Intercoolers with Stock Location or Rotated Turbo, pitch stop mount.
- 2002 Subaru WRX
- 2003 Subaru WRX
- 2004 Subaru WRX
- 2005 Subaru WRX
- 2006 Subaru WRX
- 2007 Subaru WRX
S0714-1: Designed for Top Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0715-1: Designed for Front Mount Intercoolers with Stock Location or Rotated Turbo, pitch stop mount.
- 2004 Subaru Forester XT
- 2005 Subaru Forester XT
- 2006 Subaru Forester XT
S0714-1: Designed for Top Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0715-1: Designed for Front Mount Intercoolers with Stock Location or Rotated Turbo, pitch stop mount.
- 2008 Subaru STI
- 2009 Subaru STI
- 2010 Subaru STI
- 2011 Subaru STI
- 2012 Subaru STI
- 2013 Subaru STI
- 2014 Subaru STI
S0720 (Replaced S0713-1 & S0716-1): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount. (V3 Kit also available)
S0720-1 (Replaced S0716-2): Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
- 2015 Subaru STI
- 2016 Subaru STI
- 2017 Subaru STI
- 2018 Subaru STI
- 2019 Subaru STI
S0720 (Replaced S0713-1 & S0716-1): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount. (V3 Kit also available for top mount intercoolers)
S0710: Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
- 2008 Subaru WRX
- 2009 Subaru WRX
- 2010 Subaru WRX
- 2011 Subaru WRX
- 2012 Subaru WRX
- 2013 Subaru WRX
- 2014 Subaru WRX
S0720 (Replaced S0718): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount. (V3 Kit also available for top mount intercoolers)
S0720-1 (Replaced S0718-1): Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
- 2005 Subaru Legacy GT (LGT)
- 2006 Subaru Legacy GT (LGT)
- 2007 Subaru Legacy GT (LGT)
- 2008 Subaru Legacy GT (LGT)
- 2009 Subaru Legacy GT (LGT)
S0720 (Replaced S0718): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0720-1 (Replaced S0718-1): Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
- 2007 Subaru Outback XT (OXT)
- 2008 Subaru Outback XT (OXT)
- 2009 Subaru Outback XT (OXT)
S0720 (Replaced S0718): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0720-1 (Replaced S0718-1): Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
- 2007 Subaru Forester XT (FXT)
- 2008 Subaru Forester XT (FXT)
- 2009 Subaru Forester XT (FXT)
- 2010 Subaru Forester XT (FXT)
- 2011 Subaru Forester XT (FXT)
- 2012 Subaru Forester XT (FXT)
- 2013 Subaru Forester XT (FXT)
S0720 (Replaced S0718): Designed for Top Mount or Front Mount Intercoolers with Stock Location Turbo, passenger side strut tower mount.
S0720-1 (Replaced S0718-1): Designed for Front Mount Intercoolers with Rotated Turbo, pitch stop mount.
Crawford V3 AOS Kit Fitment List by Vehicle
V3 Kit
- 2013 Subaru BRZ
- 2014 Subaru BRZ
- 2015 Subaru BRZ
- 2016 Subaru BRZ
- 2017 Subaru BRZ
- 2018 Subaru BRZ
- 2019 Subaru BRZ
- 2013 Scion FR-S
- 2014 Scion FR-S
- 2015 Scion FR-S
- 2016 Scion FR-S
- 2013 Toyota GT86
- 2014 Toyota GT86
- 2015 Toyota GT86
- 2016 Toyota GT86
- 2017 Toyota GT86
- 2018 Toyota GT86
- 2019 Toyota GT86
- 2017 Toyota 86
- 2018 Toyota 86
- 2019 Toyota 86
S0711: Designed for any modifications, centered mount between strut bars.
- 2015 Subaru WRX
- 2016 Subaru WRX
- 2017 Subaru WRX
- 2018 Subaru WRX
- 2019 Subaru WRX
S0717: Designed for Top Mount Intercoolers, front of brake fluid reservoir mount. (more fitments in R&D)
- 2014 Subaru Forester XT
- 2015 Subaru Forester XT
- 2016 Subaru Forester XT
- 2017 Subaru Forester XT
- 2018 Subaru Forester XT
S0717: Designed for Top Mount Intercoolers, front of brake fluid reservoir mount. (more fitments in R&D)
- 2008 Subaru STI
- 2009 Subaru STI
- 2010 Subaru STI
- 2011 Subaru STI
- 2012 Subaru STI
- 2013 Subaru STI
- 2014 Subaru STI
- 2015 Subaru STI
- 2016 Subaru STI
- 2017 Subaru STI
- 2018 Subaru STI
- 2019 Subaru STI
S0699: Designed for Top Mount Intercoolers, behind coolant tank mount. 2015+ STi sound generator delete. (more fitments in R&D)
- 2008 Subaru WRX
- 2009 Subaru WRX
- 2010 Subaru WRX
- 2011 Subaru WRX
- 2012 Subaru WRX
- 2013 Subaru WRX
- 2014 Subaru WRX
S0699: Designed for Top Mount Intercoolers, behind coolant tank mount. (more fitments in R&D)
- 2007 Subaru Forester XT
- 2009 Subaru Forester XT
- 2010 Subaru Forester XT
- 2011 Subaru Forester XT
- 2012 Subaru Forester XT
- 2013 Subaru Forester XT
- 2014 Subaru Forester XT
S0699: Designed for Top Mount Intercoolers, behind coolant tank mount. (more fitments in R&D)
Crawford Baja Edition (NA) AOS Kit Fitment List by Vehicle
Baja Edition Kit
- 2013 Subaru XV Crosstrek
- 2014 Subaru XV Crosstrek
- 2015 Subaru XV Crosstrek
- 2016 Subaru Crosstrek
- 2017 Subaru Crosstrek
S0698: Driver’s side intake manifold mount.
- 2012 Subaru Impreza 2.0i
- 2013 Subaru Impreza 2.0i
- 2014 Subaru Impreza 2.0i
- 2015 Subaru Impreza 2.0i
- 2016 Subaru Impreza 2.0i
S0698: Driver’s side intake manifold mount.
- 2014 Subaru Forester
- 2015 Subaru Forester
- 2016 Subaru Forester
S0698: Driver’s side intake manifold mount, non-turbo models.
- 2018 Subaru Crosstrek
- 2019 Subaru Crosstrek
S0696: Driver’s side intake manifold mount.
