Air Oil Separators

An air oil separator (AOS) sits in the engine's crankcase ventilation system. It separates oil mist from the blow-by gases before they are routed back into the intake. This range includes vehicle-specific kits for popular Australian 4x4 utes and turbo Subaru and Ford models, plus universal units. Brands include Process West, PERRIN, COBB Tuning, GrimmSpeed and Radium Engineering. You'll find more crankcase and lubrication parts in our Oiling and Crankcase range.

Shop by Vehicle

Toyota: HiLux (N70, N80), LandCruiser 200 Series (J200), LandCruiser 79 Series (J70), Toyota 86 (ZN6) and GR86 (ZN8) – Process West and PERRIN
Ford: Ranger (PX/PX2/PX3 3.2L, PX3 2.0L, PY), Focus ST (LZ) and Focus RS (LZ) – Process West and COBB Tuning
Mazda: BT-50 (UP/UR 3.2L and 2022+) – Process West
Isuzu: D-MAX MY16.5+ and 2022+ – Process West
Nissan: Navara (D40 2.5L diesel, NP300) and Patrol (GU ZD30 3.0L diesel) – Process West
Mitsubishi: Triton (MN, MQ) and Pajero (NX) – Process West
Volkswagen: Amarok (2H) 4cyl and V6 diesel – Process West
Subaru: WRX and STI across GD, GG, GR, GV and VA chassis, WRX 2022+, BRZ (ZC6/ZD8) and Outback – PERRIN, COBB Tuning and GrimmSpeed
Ram: 2500/3500 6.7L Cummins (2010–2021) – Process West SEPR8R
Universal: Process West SEPR8R Universal and Radium Engineering AOS-R (10AN ORB)

Related ranges: Catch Cans, Breather Components, Oil Coolers, Oil Filters, Oil Pumps and Sumps. You can also browse all brands.

Choosing the Right Part

Match the chassis and engine: Many kits are specific to a chassis code and engine. Examples include Ranger PX3 2.0L versus PX/PX2/PX3 3.2L, Navara D40 2.5L diesel, Patrol GU ZD30 and Amarok 4cyl versus V6 diesel. Confirm both before ordering.
Check the model year range: Subaru kits are split by chassis and year. For example, GrimmSpeed offers separate hardware kits for the GH8/GR8 WRX and the 2002–07 WRX / 2004–21 STI.
Vehicle-specific or universal: Vehicle-specific kits are designed around a particular engine bay. Universal units such as the Process West SEPR8R Universal and the Radium AOS-R (10AN ORB ports) suit custom setups and need suitable fittings and hose.
Accessories: Separate hardware kits and mounting brackets are available, such as the PERRIN FMIC mounting bracket for WRX/STI. Check whether your separator needs one.
Construction: Some units, such as the COBB Tuning Focus ST separator, are billet aluminium.

Installation & What You'll Need

Installation involves rerouting crankcase ventilation hoses and mounting the separator in the engine bay. Some kits also connect a drain or return line. Check the kit contents on each product page so you know whether hoses, fittings, brackets or hardware are included. Universal units need fittings and hose matched to their port size. Installation by a professional is recommended.

FAQ

What does an air oil separator do?
It separates oil mist from crankcase blow-by gases so less oil vapour is routed back into the intake.

Is an air oil separator the same as a catch can?
Both deal with oil vapour from crankcase ventilation, but designs differ. Check the product details, or browse our Catch Cans range to compare.

Do you have separators for diesel 4x4s?
Yes. Process West kits cover diesel models including the HiLux, LandCruiser 79 and 200 Series, Ranger, BT-50, D-MAX, Navara, Patrol GU ZD30, Triton, Pajero and Amarok.

Is there a universal option?
Yes. Choose from the Process West SEPR8R Universal and the Radium Engineering AOS-R with 10AN ORB ports.

Need help choosing? Contact our team at sales@chicaneaustralia.com.au.