SKU: 12273579771

AOS-R KIT, 2015+ SUBARU WRX, INCLUDES 20-0255

Sale price$199.32 Regular price$221.47
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Description

AOS-R KIT, 2015+ SUBARU WRX, INCLUDES 20-0255This kit is compatible with the following vehicles that use the FA20F engine (left hand drive models only): 2015+ Subaru WRX 14 18 Subaru Forester XT 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

This kit is compatible with the following vehicles that use the FA20F engine (left-hand drive models only):

2015+ Subaru WRX
14-18 Subaru Forester XT

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 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.

Same theories apply for this application. However, the direct-injected Subaru FA20F engine in particular has an inherent problem since there are no port injectors to clean the backside of the intake valves.

The AOS is constructed of CNC machined sections that screw together and are sealed with O-rings. The AOS can be completely disassembled for cleaning or servicing.

Benefits
-Effectively raises the fuel 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

2015+ Subaru WRX Installation
The Radium Engineering AOS kit installs on the LH side of the engine bay, near the brake master cylinder. The outlet (side port) of the AOS is plumbed back to the turbo inlet pipe, creating a completely sealed system.

The AOS mounts to the Radium Brake Master Cylinder Brace. This brace is REQUIRED for installation.

The PCV valve is replaced by a custom machined straight-through adapter fitting, shown below. Oil collected in the AOS drains out the bottom fitting and back into the engine block through this fitting.
Kit Contents
-Machined aluminum Radium Engineering Air/Oil Separator
-Specially designed mounting bracket
-All necessary SAE J30R7 rated PCV/Emissions hose
-Coolant hoses and fittings
-PCV delete fitting
-All necessary aluminum fittings and hose-ends
-Stainless steel mounting hardware
-20-0255 Master Cylinder Brace (20-0258-00 only)

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

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: 12273579771

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bunny
Lowell, US
★★★★★ 5
Simple, gorgeous, heavy duty
Style: L Bracket w/ Lip, Size: 11.25", Style: L Bracket w/ Lip, Size: 11.25"
I needed to mount a heavy wood shelf and wanted something with clean lines that would keep it safely in place above a bed. These are heavy duty solid iron and I mounted them into wall studs. Instructions didn't say what size drill bit to use, but 9/64" worked perfectly. The package has drywall mounts too, but I can't imagine they'd hold safely. Put the shelf up and it looks great! The lip on the front of each bracket is another plus that keeps the shelf from slipping forward.
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Reviewed in the United States on February 18, 2024
M
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Marcelo
Natrona Heights, US
★★★★★ 5
Great Brackets
Style: L Bracket w/ Lip, Size: 7.25" x 6"
Good quality, exactly what I ordered.
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Reviewed in the United States on April 8, 2026
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Lilly Mc
Omaha, US
★★★★★ 5
Beautiful shelf brackets
Style: L Bracket w/ Lip, Size: 9.25" x 6", Style: L Bracket w/ Lip, Size: 9.25" x 6"
I am extremely please with the brackets but had a hell of a time installing them. It is only me, so I had to be careful with making sure they were horizontal, etc. The little levelers are cute but definitely not a help. Use a standard size leveler. Also - I used the anchors provided for the drywall and they punched in two big holes. I ended up buying a different kind of anchor to put in the middle bracket (my first intentions were to use three brackets to make sure the shelf would hold). I was lucky that the size of the shelf I wanted coincided with the 2x4s in the walls so I was able to anchor the brackets and shelves to the 2x4s in the walls., so my shelves are very sturdy. I bought 3 sets intending to put up 4 shelves with 3 brackets but only did 2 shelves with 3 and 2 brackets, respectively. I like the look so much that I am keeping the ones that are unused and installing them in my bedroom for my books. Right now, I am extremely happy with them.
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Reviewed in the United States on June 27, 2022
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GA girl
Omaha, US
★★★★★ 4
Sturdy/Heavy brackets
Style: L Bracket w/ Lip, Size: 9.25" x 6"
We wanted to replace our awful white wire shelving in our pantry and purchased these brackets. Had the wood shelves cut to fit so very easy to install the shelving on top. The lip at the end of the bracket holds the shelf so the brackets do not need to be attached to the shelf. The brackets are very sturdy, heavy metal so they definitely hold the wood shelves and pantry items. Only complaint -the screws that are included. Some of the screws stripped or broke while trying to attach the brackets to the wall studs. They do include an extra screw in each box I guess for this purpose but we still had to purchase additional screws to replace the broken ones. Very frustrating but the finished result looks great and the brackets were an easy fix to replace the old shelving.
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Reviewed in the United States on June 7, 2023
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C Mason
Boise, US
★★★★★ 5
Sent more screws when needed!
Style: L Bracket w/ Lip, Size: 9.25" x 6", Style: L Bracket w/ Lip, Size: 9.25" x 6"
Screw heads frequently stripped, and on 3 the head sheared clear off. All this despite drilling pilot holes and lubricating screws. The seller was wonderful though and sent extra screws at no extra cost. Looks great and holds well now that complete!
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Reviewed in the United States on November 12, 2025

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