The PERRIN Air Oil Separator traps oil from the crankcase vents before it enters the intake, reduces carbon build-up, increases intercooler efficiency, which reduces the chance of performance-robbing detonation.

Increase horsepower and torque without ECU recalibration or tune! This part is designed and tested to work safely on your vehicle without any tuning required! However, more power can be gained with proper ECU tuning! Confirm any tune or recalibration you add is specific for ALL modifications added to the vehicle. 

The PERRIN Air Oil Separator is not a catch can. Catch cans capture engine blow-by and stores it in a container, which requires constant attention and removal of oil every few hundred miles. The air oil separator separates the oil from the air, draining it back to the engine, which eliminates the need for constant attention and draining of oil. As oil drains from the bottom of the PERRIN Air Oil Separator, clean oil-free air vents out of the top to rejoin the intake tract.

The PERRIN Air Oil Separator features swirl pot technology and multi-layer baffles. This design forces incoming engine blow-by to move rapidly across the baffles, separating oil from the engine blow-by. Multiple layers of baffles means more surface area to collect more oil, making for a compact and efficient design.

The base plate of the air oil separator is heated by coolant drawn from the engine. This heats the entire air oil separator to the same temperature as the engine blow-by. By keeping the air oil separator the same temperature as the blow-by, water condensation is significantly decreased, allowing oil, air, and water vapor to separate and pass through the body.

The PERRIN Air Oil Separator increases intercooler efficiency by reducing the amount of oil deposited into your intercooler and intake system! As blow-by/oil builds up inside your intercooler, the less efficient it becomes due to less heat being transferred away from your engine. This leads to power loss and detonation, which can be damaging to your engine.

Reduce carbon buildup in the combustion chamber, intake valves, and in your intake tract. Crankcase blow-by is recirculated back to the intake to be ingested by the engine, but in doing so, gets stuck in the intake tract, intake valves, and the intercooler. This builds up over time which causes a loss in power and extra wear and tear on your valves.

The low-profile aluminum fittings provided with the PERRIN Air Oil Separator are CNC machined and anodized black for both a clean, sleek look and corrosion resistance. These tough and durable fittings are designed and finished to last the life of your vehicle.

Included with the PERRIN Air Oil Separator for 2015-2018 WRX, the PERRIN Turbo Sump Pump Restrictor fixes burning oil issues relating to turboback exhausts or Stage 2 and higher tunes. 

Instead of using a universal type fitting, we have designed a purpose built crank case fitting that does the job perfectly. Like the air oil separator body, the drain fitting is threaded to except virtually any kind of fitting to allow for easy customization on special projects.

Powder-coated for protection against the elements, the textured finish will look awesome for years to come. The PERRIN Air Oil Separator is available in black, red, or neon yellow powder coating.

Subaru EJ engines have 3 crank case type vents located on the engine blow and valve covers, and the Subaru EJ engines have 2 crank case type vents. Each PERRIN Air Oil Separator is designed to connect to each of these separately without requiring any T-connections. This allows for better venting and reduces the chance of oil being ingested during high G corners (common issue on flat type or boxer engines).