Radium Air Oil Separator Return Kit (AOS-R Kit) - 2013-2016 Scion FR-S / 2013-2020 Subaru BRZ / 2017-2020 Toyota 86
Radium Air Oil Separator Return Kit (AOS-R Kit) - 2013-2016 Scion FR-S / 2013-2020 Subaru BRZ / 2017-2020 Toyota 86
Radium Engineering
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PRODUCT DETAILS
RallySport Direct carries highly engineered products designed to improve the performance and longevity of your vehicle brought to you by Radium Engineering.
This is the Radium Engineering Air Oil Separator R Kit. In high-powered and modified Subaru engines, they tend to create excessive blow-by with oil vapors and gasses. in these cases, a regular small catch can fill up quickly with oil and not be adequate. The AOS R kit will keep blow-by oil and other pollutants out of the intake pipe, intake manifold, turbocharger, and intercooler (for those with aftermarket forced induction) during all engine loads. The main difference is that the AOS R system returns what is collected into the oil pan, so no servicing is required. The built-in heater keeps water from condensing in the AOS, and because water is denser than oil, an integrated water trap is found around the bottom perimeter of the can. This overall design prevents water from descending into the oil pan if ever present. Additionally, because the water is trapped against the heater, it will eventually boil and evaporate out of the system.
HIGHLIGHTS:
- The AOS is constructed of CNC-machined sections that screw together and are sealed with O-rings
- Prevents oil buildup in the intake or intercooler system walls, throttle body, and intake manifold
- Lowers hydrocarbon emissions
- Effectively raises the octane and increases engine performance with cleaner inlet air
- Height: 6.3" without fittings
- Diameter: 3.45" round
- Capacity: 20.3 oz (600mL)
INCLUDES:
- Machined aluminum Radium Engineering Air Oil Separator
- Subaru-specific designed mounting bracket
- All necessary SAE J30R7-rated PCV/emissions hose
- Coolant hoses and fittings
- All necessary aluminum fittings and hose-ends
- Stainless steel mounting hardware
NOTES:
- 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 any water condensation from freezing and potentially clogging the hose
- For RHD vehicles, Radium's Universal AOS-R must be used for custom mounting and plumbing
WHY WE CARRY THIS
We only list parts we’d run ourselves or recommend to a friend building a real car. If it feels vague, unverified, or inconsistent, it doesn’t make the cut.
- Fitment-first mindset — no “universal” roulette
- Brand reputation matters — we favor proven manufacturing
- Support that actually responds with real answers
WHAT TO EXPECT
This is the clean path: correct fitment, clean install, and results that match the intent.
- Install-ready experience with correct mounting where provided
- Finish that holds up to real driving, not just photos
- Selections on this page drive the exact fitment shipped
TRUST, BUILT INTO THE PROCESS.
Anyone can list parts. We curate what belongs on a serious build. Our goal is simple: fewer surprises, cleaner installs, and confidence when you hit “Buy.”
Fitment checked
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Proven manufacturing and consistent quality matter more than hype. We bias toward what actually holds up.
Real support
If you have a question, you’ll get a human answer that helps you finish the build — not a copy-paste shrug.
RallySport Direct carries highly engineered products designed to improve the performance and longevity of your vehicle brought to you by Radium Engineering.
This is the Radium Engineering Air Oil Separator R Kit. In high-powered and modified Subaru engines, they tend to create excessive blow-by with oil vapors and gasses. in these cases, a regular small catch can fill up quickly with oil and not be adequate. The AOS R kit will keep blow-by oil and other pollutants out of the intake pipe, intake manifold, turbocharger, and intercooler (for those with aftermarket forced induction) during all engine loads. The main difference is that the AOS R system returns what is collected into the oil pan, so no servicing is required. The built-in heater keeps water from condensing in the AOS, and because water is denser than oil, an integrated water trap is found around the bottom perimeter of the can. This overall design prevents water from descending into the oil pan if ever present. Additionally, because the water is trapped against the heater, it will eventually boil and evaporate out of the system.
HIGHLIGHTS:
- The AOS is constructed of CNC-machined sections that screw together and are sealed with O-rings
- Prevents oil buildup in the intake or intercooler system walls, throttle body, and intake manifold
- Lowers hydrocarbon emissions
- Effectively raises the octane and increases engine performance with cleaner inlet air
- Height: 6.3" without fittings
- Diameter: 3.45" round
- Capacity: 20.3 oz (600mL)
INCLUDES:
- Machined aluminum Radium Engineering Air Oil Separator
- Subaru-specific designed mounting bracket
- All necessary SAE J30R7-rated PCV/emissions hose
- Coolant hoses and fittings
- All necessary aluminum fittings and hose-ends
- Stainless steel mounting hardware
NOTES:
- 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 any water condensation from freezing and potentially clogging the hose
- For RHD vehicles, Radium's Universal AOS-R must be used for custom mounting and plumbing
