Air Oil Separator-Return (AOS-R) Kit Radium Engineering for Scion FR-S/Toyota GT86/Subary BRZ (LHD) - USA-RAD-20-0351 - COMPATIBILITY12-16 Scion FR-S (LHD)12-21 Toyota GT86 (LHD)12-20 Subaru BRZ (LHD High-powered modified Toyota 4U-GSE and Subaru FA engines tend to generate excessive blow-by oil and gasses. In these cases, an ordinary small catch can may quickly fill with oil and not be adequate. Like the Radium Engineering Dual Catch Can Kit, the AOS-R (Air Oil Separator-Return) kit is responsible for keeping blow-by oil and other pollutants out of the intake pipe, manifold, turbocharger, and intercooler during all engine loads. The main difference is that an AOS-R system returns what is collected back into the oil pan so there is no servicing required. The built-in heater keeps water from condensing in the AOS-R. And because water is more dense than oil, there is an integrated water trap found around the bottom perimeter of the can.  This prevents water from descending into the oil pan if ever present. Furthermore, because the water is trapped against the heater, it will eventually boil and evaporate out of the syste DIMENSIONSAOS-R Height: 6.3" (without fittings)AOS-R Diameter: 3.45" Round AOS-R Capacity: 20.3 oz (600m L) PORTS Inlet: 7/8"-14 threaded for 10AN ORB fittings Outlet: 7/8"-14 threaded for 10AN ORB fittings Return: 7/8"-14 threaded for 10AN ORB fittings Coolant: 7/16"-20 threaded for 4AN ORB fittings (x 2) BENEFITS-Effectively raises the octane and increases engine performance with cleaner inlet air -Prevents oil buildup in the intake or intercooler system walls, throttle body, intake manifold, etc.-Lowers hydrocarbon emissions INCLUDED-Machined alumium Radium Air Oil Separator-Specially designed mounting bracket-SAE J30R7 rated PCV/Emissions hose-Coolant heater hoses and fittings-All necessary aluminum fittings and hose-ends-Stainless steel mounting hardware  *If operated in freezing environments, Radium Engineering recommends installing insulation sleeving (not included) over any hose exposed to cold air flow. This will help prevent the natural phenomenon of water condensation freezing and potentially clogging the hose. *For RHD vehicles, our Universal AOS must be used for custom mounting and plumbing. Instruction PDF