Subaru OEM filters C&P - Bypass relief pressure measured

[Ranger83]

The primary longevity improvement for WRX is the Killer B oil pan, which holds six quarts. They used to be billet machined but are now cast aluminum.

https://www.killerbmotorsport.net/shop/category/oiling-oil-pan-25

Track cars also have better pickups and an air/oil separator.

On my 3.0R’s we use Purolator Boss filters.

This video is a year old. He states the Mazda OEM filter was the same.

 

[Dave Hess]

24 bucks spent straight from the local dealership to address the elephant in the room: The long debated bypass opening pressure of Subaru OEM filters. Both filters look very high quality as expected and thick can took a bit of elbow grease to cut open. Not much to say other than they're very well made jammed packed with many pleats. Both filters have a bypass opening diameter of 10mm and the Chatillon push force gauge read >3.5 pounds of force for the bypass valve to start opening, which estimated an opening pressure of 28.75 PSI. Very strong spring by the feel of the finger.

Take it for what it is or believe whatever you want, looks like the 2022 WRX in the family fleet will be sticking with OEM for now while still under warranty.
Dealership no longer sell the blue cans so these 2 were the only samples so far.

Subaru OEM filters - virgin sample

• Mewbs
• May 30, 2024
• 10

Subaru 15208AA20A & 15208AA170
Cut opened to measure bypass pressure...
OP Thread...

Small chart I made of all filter C&P I did so far here. I'll likely add as I cut open more filters over time.

View attachment 222196

Nice photos and write up.