SKU: 14371857191

Radium Engineering Air Oil Separator AOS-R – 2015-2020 Subaru WRX STi

Sale price$189.45 Regular price$210.50
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Description

Radium Engineering Air Oil Separator AOS-R – 2015-2020 Subaru WRX STiHigh powered modified Subaru 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 Subaru Dual Catch Can Kit, the AOS (Air Oil Separator) 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

High-powered modified Subaru 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 Subaru Dual Catch Can Kit, the AOS (Air Oil Separator) 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. 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 system. The AOS is constructed of three CNC machined sections that screw together and are sealed with O-rings.

Measurements
AOS Height: 6.94″ (top of the dipstick to bottom of AOS)
AOS Diameter: 3.45″ Round
AOS Capacity: 20.3 oz (600mL)


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 aluminum Radium Engineering Air Oil Separator
-Specially designed mounting bracket (see note at bottom of page)
-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 airflow. This will help prevent the natural phenomenon of water condensation freezing and potentially clogging the hose.

*For RHD vehicles, our Universal AOS-R must be used for custom mounting and plumbing.

*The Radium AOS-R kit may not be compatible with all other aftermarket products. 

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 14371857191

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Jerrod Bennett
Phoenix, US
★★★★★ 5
Best brown jeans for the price!!!
Color: Deep Brown, Size: 32W x 32L
Really nice vibrant brown color in person. They fit perfectly and the length is spot on. Look great 4 Less!!
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Reviewed in the United States on June 3, 2026
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Kathryn Eberly
Dallas, US
★★★★★ 5
Same sizes but different fits
Color: Light Green-new, Size: 32W x 32L
Great color and good fit. Feels more like a Jean. I bought two pair-exact same size. 32w x 32 length. Light green was exactly what I wanted. The maroon red was more like a jegging than jeans. Not what I wanted. Supposedly same style - so just be aware fits were completely different!
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Reviewed in the United States on May 1, 2026
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Bryan Brook
Chelsea, US
★★★★★ 4
Good product with quality-control issues
Color: Dark Grey, Size: 31W x 31L
I really like these jeans. I own them in almost every color they offer, but the manufacturing consistency is hit or miss. The latest pair I bought has a much smaller pocket opening than the others. I also always order the same size (31×31), but when I got the red pair they were ridiculously long, more like a 31×36. And the first khaki pair I bought had pockets about half as deep as the rest. My iPhone would literally stick out of them. That said, for the price and overall look, they’re still a solid buy.
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Reviewed in the United States on February 15, 2026
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George E.M.Yates
Birmingham, US
★★★★★ 5
Comfortable
Color: Deep Brown, Size: 34W x 32L
Nicely fit.
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Reviewed in the United States on May 25, 2026
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scott
San Leandro, US
★★★★★ 5
Just buy. You will want more in different colors
Color: Lemon Yellow, Size: 40W x 32L
Excellent pants. Super comfy
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Reviewed in the United States on May 20, 2026

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