GrimmSpeed Red Air / Oil Separator Subaru WRX 02-07 / STI 04-21 / Forester XT 04-08 | 078006R

  Fitment Information: 2002-2007 Subaru WRX 2004-2021 Subaru STI 2004-2008 Subaru Forester XT Features: An Air Oil Separator has one job: remove the oil from the engine ventilation system so that the oil doesn't get sent through the intake system. When there is oil in your system, it results in reduced fuel octane, higher chance of engine knock (detonation), worse emissions, and higher oil consumption.The GrimmSpeed Air/Oil Separator has a unique design that allows you to maintain your PCV Valve while separating the oil out of the crankcase and head ventilation air! This AOS will allow your engine to run more efficiently due to the separation of oil from the intake system. In typical GrimmSpeed fashion, we have made a very compact unit that packs a powerful punch and looks good while doing it. No more having to constantly check or empty your catch can. The GrimmSpeed AOS coalesces oil without using a mesh media as mesh medias can cause contaminants to collect and build up resulting in