Subaru and 27psi bypass Filter selection

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Jul 1, 2008
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10
Location
Ohio
Called Mobil1 customer service and they verified that the M1-101A has a b/p pressure setting of 18 vs 27 for the OEM filter for 2018 Subaru Legacy 2.5i. They said that they stand behind their product, and the Mobil1 filter can be used for that application, I would to like to hear from Subaru owners who have figured out that the OEM filter is not the best filter available and what do they use in an after-market filter. I have been using Wix 57055XP without issues. Thank you for your responses. Enjoy this website a lot!
 
Bypass seldom comes into play unless you have an exceptionally small filter, use 10W or thicker oil and go to highway speed before it gets warm. Even then, the oil in the pan is filtered it would need to pick up dirt during the brief warm up period. The bypass filter construction and setting is not precise,most of them I would be surprised to see less than a +-5 psi tolerance, Even split pleats do not seem to shorten engine life.

Don't worry be happy.

Rod
 
Originally Posted by ragtoplvr
use 10W or thicker oil and go to highway speed before it gets warm.

Rod


I cant agree 10w has nothing to do with it. a 0w or 5w could be thicker if its 10f colder.

also 10w is the winter rating not a thickness.
 
Let me summarize for you ...

For turbo's, the higher by-pass setting MIGHT matter, in a poorly maintained engine, where the turbo screen bolts MIGHT get clogged, if there were too many by-pass events with REALLY dirty oil and filter. MAYBE.

In a non-turbo engine, it won't make any difference.


That being said, the WIX 7055's are well built, and have the " correct " by-pass setting. They work, and you don't need to stress about the Subaru by-pass spec.
 
Originally Posted by CincyFritz
Called Mobil1 customer service and they verified that the M1-101A has a b/p pressure setting of 18 vs 27 for the OEM filter for 2018 Subaru Legacy 2.5i. They said that they stand behind their product, and the Mobil1 filter can be used for that application.


The Mobil 1 filter may be less flow restrictive than the OEM filter, therefore the Mobil 1 bypass setting can be lower. If Mobil specifies that filter, then they most likely tested or analyzed the "flow vs delta-p" and determined the 18 PSI bypass is adequate.
 
Originally Posted by Rand
Originally Posted by ragtoplvr
use 10W or thicker oil and go to highway speed before it gets warm.

Rod


I cant agree 10w has nothing to do with it. a 0w or 5w could be thicker if its 10f colder.

also 10w is the winter rating not a thickness.


10W at -10 deg F is still thicker than 5W or 0W.

But they are all still thick enough at -10 F to put a filter in bypass if the engine revs get high enough. Always best practice to keep engine revs low until the oil warms up.
 
OP, If you want the "best" filtration, then sadly, the Wix XP/Napa Platinum does not meet the criteria on efficiency. It's somewhere around 50%@20 microns, worse than the factory filter you appear to dislike.

Napa Gold 7055 is about the only one that checks off every single criteria of the factory filter, but I would be perfectly fine running a Fram Ultra 7317 as well. IMO, those Mobil 1 filters fall into about a mid-grade tier since they changed the media so they could write "Good for 20k miles" on the box.

In the big picture, good air filtration is the first key to engine longevity. After that, the act of just changing the oil filter is way more important than the filter you use. I'd have no problems running the NG 7055 for 10k, or the Fram Ultra to 20k. Considering your factory OCI is 6k, you either run the NG for 1 OCI, or the Fram XG for two OCI. Your pick. Either one will deliver results that are statistically indeterminable from any other filter... pick what makes your heart happy and AWD on your way!
thumbsup2.gif
 
Originally Posted by geeman789
Let me summarize for you ...

For turbo's, the higher by-pass setting MIGHT matter, in a poorly maintained engine, where the turbo screen bolts MIGHT get clogged, if there were too many by-pass events with REALLY dirty oil and filter. MAYBE.

In a non-turbo engine, it won't make any difference.


That being said, the WIX 7055's are well built, and have the " correct " by-pass setting. They work, and you don't need to stress about the Subaru by-pass spec.



Huh!?

If the turbo screen clogs, it will increase ALL upstream pressure, meaning there won't be ANY appreciable change in differential pressure across the filter.

The dP across the filter is based on the flow rate of oil (engine/oil pump speed), the viscosity of the oil and the makeup of the filter.

Take-away: keep the engine RPM low at cold oil temps.

//

OP, after running Subaru OE filter almost exclusively in my previous '06 WRX and '08 STI I gave up. I've been running Fram Ultra (previously Extended Guard) filters exclusively for a long time now, for the following reasons:
 
I will look at the NAPA 7055. We do about 8k a year and change every 6 months. Since you are SubieRudyRoo, you must know about Jeffersonville Gold...Idemitsu SM/GF5. My Subie loves that stuff. Does not use a drop! Thanks again.
 
Originally Posted by CincyFritz
I will look at the NAPA 7055. We do about 8k a year and change every 6 months. Since you are SubieRudyRoo, you must know about Jeffersonville Gold...Idemitsu SM/GF5. My Subie loves that stuff. Does not use a drop! Thanks again.


Your '18 FB25 is the same as my '15 FB25. It will very likely love anything and not burn a drop on anything. Or are you saying that you've tried oils that resulted in some consumption?

If I were you, I'd change my oil and filter once/year. EASY
 
Originally Posted by CincyFritz
I would to like to hear from Subaru owners who have figured out that the OEM filter is not the best filter available...


The Subaru OEM oil filter is perfectly adequate, I am always curious to know what may lead anyone to think otherwise.

The answer to your general question is to use a WIX/Napa Gold oil filter if the bypass spec is important to you and want marginally better efficiency than the Subaru OEM oil filter.
 
The Fram XG7317 has a bypass valve that opens at 13 PSI. That Fram filter does not meet the requirement. It open at half the designed pressure for a Subaru engine. When the bypass opens at just 13 PSI, the filter is 0% efficient.
 
I'd like to see some math behind the effect a pressure relief valve has on the overall efficiency of a filter combined with how good the filter itself actually performs.

What is worse?

A. The filter performs at 50% efficiency @ 20-micron for 99.9% of the time and 0% efficiency for 0.1% of the time when PRV is open.

B. The filter performs at 97% efficiency @ 20-micron for 99.8% of the time and 0% efficiency for 0.2% (twice as often) when PRV is open.

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Originally Posted by wdn
The Fram XG7317 has a bypass valve that opens at 13 PSI. That Fram filter does not meet the requirement. It open at half the designed pressure for a Subaru engine. When the bypass opens at just 13 PSI, the filter is 0% efficient.


Hi there, you are
18.gif


In fact you are not only beating a head horse but you are taking that dead horse that has been beaten, buried, dug up, rebeaten, reburied, and digging it up again so you can beat it some more.

I am just going to leave some interesting reading I found:

https://www.bobistheoilguy.com/foru...an-share-fram-xg7317s-flow-delta-p-graph

https://www.bobistheoilguy.com/foru...he-horse-to-death-subaru-and-fram-ultras

https://www.bobistheoilguy.com/foru...s-fram-comparison-fits-honda#Post3114348

https://www.bobistheoilguy.com/foru...xp-and-fram-xg7317-cut-open-and-compared
 
Ignatius, Fram XG7317 does not meet the Subaru spec. Specs are specs. I don't know who appointed you the project historian for Bob, but a bunch of old threads are immaterial. In any case nobody is shooing me off this one. If you would care to identify some other aftermarket filters that do meet the spec, by Fram or others go ahead.

Today's topic is " Subaru and 27psi bypass Filter selection".
 
Not a Subaru owner, yet. Like what I hear about them though. How about Purolator Boss PBL14615 has 20-30 bypass.
 
Unless the Subaru manual or some other service bulletin claims the 27psi valve is required (and lists the test method & parameters & reasons with data), your vehicle doesn't need it. You're splitting hairs.

The anal retentive powertrain engineers just want the filter filtering as much as possible (no bypass), whereas the warranty guys just want oil without an adjective in front of it and a filter that doesn't create debris.

How much "debris" does your engine create that it needs filtration at all the little blips of the PRV up to 27psid? I'd say the higher PRV setting would be most useful during the first couple oil changes for flushing out all the casting BS, but after that your engine just needs oil, and the oil in the sump is clean enough. On a small gas engine, the filter is there for stopping anomalies from tanking an engine. Dirt in oil only comes from 2 places -- throttle body air or internal wear. Oil is pretty clean despite it's brown appearance after it's been used.

Filters are not 100% efficient. Subaru historically uses a pretty high air perm paper that's made to stop the big stuff.

Besides, doesn't FRAM make the Subaru?? If there was any issue, it would be in FRAM's best interests to abide by their customers' preference. But they don't. Because PRV of 13 or 27 psid doesn't matter!!
 
Originally Posted by wdn
Ignatius, Fram XG7317 does not meet the Subaru spec. Specs are specs. I don't know who appointed you the project historian for Bob, but a bunch of old threads are immaterial. In any case nobody is shooing me off this one. If you would care to identify some other aftermarket filters that do meet the spec, by Fram or others go ahead.

Today's topic is " Subaru and 27psi bypass Filter selection".

Good times.
 
A further note, on Amazon the Puro Boss PBL14615 states compatible with Subaru. The 20-30 bypass is in line, likely the same as, a 27 psi stated as one number. If not wanting the OE that is what I would use or the Wix.
 
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