Oil Separators & Vent lines
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
This kit is the complete factory-specified breathing and oil-vapour separation system for the 981 Boxster and Cayman engines. It comprises the oil-separator unit, two vent valves, and all necessary hoses. Together, they ensure the crankcase is ventilated properly, blow-by vapours are separated, and only clean, oil-free air is recirculated or vented.
Fits:
Porsche 981 Boxster 2012 - 2016
Porsche 981 Boxster Spyder 2016>>
Porsche 982 Boxster GTS 4.0L 2017>>
Porsche 981C Cayman 2014 - 2016
Porsche 981C Cayman GT4 2016>>
Porsche 982C Cayman GT4 4.0L 2017>>
Diagram ref no 12 (Oil separator)
Diagram ref no 1, 2, 12 and 14.
Kit Contents:
1× 0PB115099A - Air-Oil Separator (AOS) body / main separator unit
1× 9A110503801 - Crankcase Vent Valve (cylinders 4–6)
1× 9A110503900 - Crankcase Vent Valve (cylinders 1–3)
1× 9A110752020 - Crankcase Vent Hose / Breather Line
1× 9A110751501 - Additional Crankcase Breather Hose (or secondary vent line)
All parts are Genuine Porsche OEM - manufactured to original factory specifications for materials, dimensions, sealing and performance.
Recommended when replacing the AOS system, during engine maintenance, or when experiencing symptoms of AOS failure (oil consumption, smoke, vapour in intake, etc.).
Replace all components together as a kit for best sealing, balance, and long-term reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
OILSEPKIT981
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- Porsche Boxster 987 MKII 2.9L 2009-2012
- Porsche Boxster S 987 MKII 3.4L 2009-2012
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche Boxster GTS 718 4.0L Manual (400 Bhp)
- Porsche Boxster GTS 718 4.0L PDK (400 Bhp)
- Porsche Boxster Spyder 718 4.0L (420 Bhp)
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
- Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
- Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L
The Genuine Porsche Air-Oil Separator is the factory-specified unit responsible for separating oil mist from crankcase blow-by gases on modern Porsche flat-6 engines. As part of the PCV system, it ensures clean ventilation, stable crankcase pressure, and proper oil control - critical for protecting the intake system and maintaining optimal engine performance.
Fits:
Porsche 987.2 Boxster 2009 - 2012
Porsche 981 Boxster 2012 - 2016
Porsche 981 Boxster Spyder 2016>>
Porsche 982 Boxster GTS 4.0L 2017>>
Porsche 987C.2 Cayman 2009 - 2012
Porsche 981C Cayman 2014 2016
Porsche 981C Cayman GT4 2016>>
Porsche 982C Cayman GT4 4.0L 2017>>
Diagram ref no 16
A factory-original air-oil separator designed to filter blow-by vapours, remove oil mist, and maintain stable crankcase ventilation.
Sold individually. It is recommended to also inspect and, if necessary, replace associated hoses and seals when fitting a new separator to ensure full system integrity.
This AOS:
• Removes oil droplets and vapour from crankcase gases before they enter the intake
• Maintains correct crankcase vacuum and pressure balance
• Reduces oil consumption and prevents oil contamination in the intake tract
• Helps prevent carbon build-up, fouled sensors, and smoky exhaust
• Ensures emissions compliance and proper engine breathing
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
0PB115099A
The product you are viewing cross references to these numbers
- Porsche Boxster 987 MKII 2.9L 2009-2012
- Porsche Boxster S 987 MKII 3.4L 2009-2012
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
- Porsche Boxster GTS 718 4.0L Manual (400 Bhp)
- Porsche Boxster GTS 718 4.0L PDK (400 Bhp)
- Porsche Boxster Spyder 718 4.0L (420 Bhp)
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
- Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
- Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L
A crankcase air-oil separator (AOS) that traps oil droplets and vapour from the engine’s blow-by gases and returns cleaned air to the intake system while keeping oil inside the engine’s lubrication system.
Sold individually. It is recommended to also inspect and, if necessary, replace associated hoses and seals when fitting a new separator to ensure full system integrity.
Fits:
Porsche 987.2 Boxster 2009 - 2012
Porsche 981 Boxster 2012 - 2016
Porsche 981 Boxster Spyder 2016>>
Porsche 982 Boxster GTS 4.0L 2017>>
Porsche 987C.2 Cayman 2009 - 2012
Porsche 981C Cayman 2014 2016
Porsche 981C Cayman GT4 2016>>
Porsche 982C Cayman GT4 4.0L 2017>>
Diagram ref no 16
This air-oil separator is an replacement unit designed to filter crankcase blow-by vapours on Porsche engines, separating oil mist from the air before routing clean air back into the intake or ventilation system.
Over time AOS units degrade - internal baffles can become clogged, seals can fail, or plastic can crack due to heat cycles. A faulty or clogged separator may allow oil vapour into the intake, causing:
• Increased oil consumption and oil-soaked intake/tracks.
• Blue or grey smoke from exhaust, rough idle, misfires or poor running.
• Sludge or carbon buildup, fouled sensors, and potential engine damage.
Replacing with a correct fresh separator restores clean crankcase ventilation, keeps oil inside, and helps maintain reliable performance and engine health.
You should replace the air-oil separator when:
• You notice oil in the intake system, oil residue around intake or throttle body, or excessive oil consumption.
• The separator is showing signs of age: cracks, hardened plastic, degraded seals, or clogging.
• Your engine exhibits excessive smoke, rough idling, or misfires potentially related to intake contamination.
• Carrying out engine maintenance, PCV servicing, or installing new hoses/seals.
• The separator hasn’t been replaced for many years or high mileage - preventive maintenance helps avoid more serious issues.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
0PB115099A
The product you are viewing cross references to these numbers
- Porsche Boxster 987 MKII 2.9L 2009-2012
- Porsche Boxster S 987 MKII 3.4L 2009-2012
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12
- Porsche 997 MKII Turbo 2010-13
- Porsche 991.1 Carrera C2 3.4L (350Bhp) 2012-16
- Porsche 991.1 Carrera C2S 3.8L (400Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350Bhp) 2012-16
- Porsche 991.1 Carrera C4S 3.8L (400Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560Bhp) 2014-16
- Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
Sold each - 2 required per car

Fits:
Porsche 987.2 Boxster / Cayman - 2009 to 2019
Porsche 987.2 Boxster S / Cayman S - 2009 to 2012
Porsche 981 Boxster / Cayman - 2013 to 2016
Porsche 981 Boxster S / Cayman S - 2013 to 2016
Porsche 981 Cayman GT4 - 2016
Porsche 997.2 Carrera 2 / Carrera 4 - 2009 to 2012
Porsche 997.2 Carrera 2S / Carrera 4S - 2009 to 2012
Porsche 997.2 turbo - 2009 to 2012
Porsche 991.1 Carrera 2 / Carrera 2S - 2012 to 2016
Porsche 991.1 Carrera 4 / Carrera 4S - 2012 to 2016
Porsche 991 turbo - 2012 to 2019
Click 'Zoom in' for large parts diagram.
Diagram ref no 12
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99970765140
The product you are viewing cross references to these numbers
Oil Separators & Vent Lines – Maintain Clean Airflow and Engine Efficiency
The oil separator and vent line system plays a critical role in your Porsche’s crankcase ventilation process. By separating oil vapour from the engine’s blow-by gases, these components ensure only clean air is returned to the intake system — reducing emissions, preventing carbon build-up, and maintaining consistent engine performance.
At Design911, we stock a complete range of oil separators, breather hoses, and vent lines designed for Porsche engines of all generations. Manufactured from high-grade, heat- and oil-resistant materials, these components are built to handle the demands of high-performance driving, ensuring a tight seal, proper ventilation, and long-lasting reliability.
Whether you’re maintaining a daily-driven 911 or servicing a track-ready Cayman, our oil separators and vent lines help preserve your engine’s efficiency, longevity, and power output.
What Do Oil Separators & Vent Lines Do?
The oil separator and vent system controls crankcase pressure and removes oil vapour from the air circulating inside the engine.
Core Functions:
- Separate oil vapour from crankcase gases, keeping intake air clean.
- Prevent oil from entering the intake manifold or combustion chamber.
- Maintain stable crankcase pressure for efficient engine breathing.
- Reduce harmful emissions and extend engine life.
- Support consistent power delivery and smooth idle performance.
By ensuring clean ventilation and stable pressure, these components protect your Porsche’s engine from oil contamination and performance loss.
Why Do Oil Separators & Vent Lines Fail?
Over time, heat cycles, oil vapours, and pressure fluctuations cause these parts to degrade or clog, leading to poor ventilation and increased oil consumption.
- Common Causes of Failure Include:
- Clogged internal membranes in the separator.
- Cracked or brittle vent lines from heat and age.
- Oil leaks from worn seals or connections.
- Vacuum leaks, causing rough idling or poor throttle response.
- Build-up of sludge or condensation within breather hoses.
Typical symptoms include increased oil consumption, blue exhaust smoke, rough idle, or oil leaks around the intake area, all indicating the need for inspection or replacement.
Why Replace Components?
Replacing a faulty oil separator or vent line restores proper crankcase ventilation and prevents costly engine issues like carbon build-up or oil contamination. Our precision-engineered replacements are designed for accurate fitment and long-term durability, ensuring your Porsche operates efficiently.
Key Benefits:
- Restores clean airflow and stable crankcase pressure.
- Reduces oil leaks and smoke from the exhaust.
- Improves fuel efficiency and throttle response.
- Constructed from high-quality, heat- and oil-resistant materials.
- Direct-fit compatibility with Porsche engines.
- Ideal for maintenance, rebuilds, or performance tuning.
Upgrading or replacing your oil separator and vent lines is essential for maintaining your Porsche’s smooth performance and clean emissions system.
Highlights:
- High-quality Porsche oil separators, breather hoses, and vent lines.
- Ensures clean crankcase ventilation and stable engine pressure.
- Reduces oil leaks, smoke, and carbon build-up.
- Durable construction for long-term reliability.
- Direct-fit for Porsche 911, Cayman, Boxster, Panamera & more.
- Perfect for preventive maintenance or full engine rebuilds.