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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T Wolf
Dallas, US
★★★★★ 5
Great for strong chewing dogs. Entertaining too!
Flavor Name: Peanut Butter, Size: Medium
My black lab can destroy the toughest of dog chew toys, but he's not destroyed this peanut. I fill it with peanut butter, yogurt, pumpkin or apple sauce and freeze it. It keeps him entertained for quite a while. When the filling is gone, he leaves it alone or carries it around begging for a filled one.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 31, 2026
H
Verified Purchase
Heather Murphy
Omaha, US
★★★★★ 5
Super cute! If you have one dog it'll last a while. If you have more than one...buy two.
Flavor Name: Marshmallow & Peanut Butter, Size: Large
This is THE FAVORITE chew toy in our household. We have two grown labs and a 10 month old mutt and they all love this toy. They got a variety of chew toys at Christmas and this is the one that they steal from each other. That said, they've definitely managed to kill it. It's well worth the money and it's held up well to heavy chewers but four months later and we're going to have to buy a new one. It's now a stub. They managed to break off all the marshmallows about a week ago and the stick itself is more like a chunk now but we definitely got our money's worth.
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Reviewed in the United States on May 1, 2025
A
Verified Purchase
AvidShopper333
Phoenix, US
★★★★★ 5
Lasting 6 months in! Great smell.
Flavor Name: Marshmallow & Peanut Butter, Size: Large
This actually does smell like marshmallows which is definitely more pleasant than most dog chews!! It has held up to our power chewer. It’s a bit heavy for our smaller dog but he manages and it’s quite funny!! It’s a bit hard but that’s why it is holding up. Would buy again if this one ever wears out.
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Reviewed in the United States on January 3, 2026
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Erika
Chelsea, US
★★★★★ 4
Great product
Flavor Name: Peanut Butter, Size: Medium
I have a very active, medium sized dog (heeler). I wish this product was just a little bigger but it is still a great product. I fill it with pureed meat baby food and freeze. A 2.5oz jar will fill this product about 2 times. This keeps my dog busy for a while. Its also great when she's outside on a hot day. I absolutely recommend this product and at such a great price ($6 when I purchased it) i may buy a few more so I'll always have a frozen one ready when needed.
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Reviewed in the United States on March 17, 2025
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Steph
Carnegie, US
★★★★★ 5
Extra durable and hard
Flavor Name: Marshmallow & Peanut Butter, Size: Large
Much harder and tougher than most of the chews and bones I get. Too tough for my own dog, but it’s become a favorite of two other dogs in my life who are stronger chewers. Also looks adorable when they carry it around.
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Reviewed in the United States on October 5, 2025

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