This I Build Race Cars Air Oil Separator kit is a great choice for your Subaru. It fits 2004 - 2021 Subaru STI, 2006 - 2007 Subaru WRX (08 - 14 WRX can work with STi intake manifold update), and 2004 - 2008 Subaru Forester XT. It also works with many other vehicles with EJ25 engine swaps using OEM STi or WRX aluminum intake manifolds. This triple - pass AOS has well - designed diameters and cross - sections to remove various oil droplet sizes. Installed directly above the main crank case vent between the intake manifold and the TMIC, it offers a clean look and short hose routing. The oil drains back into the block, so you never need to empty it. The spiral baffles with small ridges collect oil, keeping it out of the airflow and draining it down. You can easily clean the internals by disassembling the unit with the tool - free thumb screw on top. Key features include a drive - by - wire throttle body, carbon fiber outer housing for a high - performance feel, retaining factory PCV functionality, and easy assembly. The kit includes the AOS01 Assembly, mounting bracket, and all necessary hoses and clamps.
Using this air oil separator is easy. First, find the main crank case vent between the intake manifold and the TMIC of your Subaru. Then, install the AOS01 assembly right above it using the included mounting bracket. Connect all the hoses and secure them with the provided hose clamps. This product is designed to drain oil back into the block, so you don't need to empty it. But you should clean the internals regularly. Just use the tool - free thumb screw on top to disassemble the unit and clean it. Remember, this separator works well with specific Subaru models and some vehicles with EJ25 engine swaps using certain intake manifolds. Make sure your vehicle meets these requirements before installation.
