PERRIN 02-14 Subaru WRX / 04-21 STI / 05-09 LGT & OBXT (w/FMIC Only) Air Oil Separator - Red

The PERRIN Air Oil Separator prevents oil from entering the intake by capturing it from the crankcase vents. This reduces carbon build-up, improves intercooler efficiency, and lowers the risk of performance-degrading detonation. It is a maintenance-free closed-loop system, separating oil from the air and draining it back to the engine, unlike traditional catch cans that require constant draining. The separator features swirl pot technology and multi-layer baffles, forcing incoming engine blow-by to move rapidly across the baffles, separating oil from the blow-by. The base plate is heated by coolant, significantly decreasing water condensation and preventing sludge buildup. It reduces carbon buildup in the combustion chamber, intake valves, and intake tract. The low-profile aluminum fittings are CNC machined and anodized black for corrosion resistance. The product is powder-coated for protection and is available in red. It is designed specifically for Subaru engines, connecting to each crankcase vent separately for better venting and reduced oil ingestion during high G corners. No tuning is required for installation, though more power can be gained with proper ECU tuning.