Wix re efficiency increasing with use

[ZeeOSix]

Lake has a close connection with Wix and has done a couple oil filter vids about them. In one he also stated that high efficiency filters are restrictive. Some are, but as we know many are high flow and high efficiency. Perhaps Lake is getting both blanket statements from Wix not Donaldson.

As the thread linked below shows, the difference if dP vs flow with hot oil between what someone considers a "restrictive" oil filter and one "that's not restictive" is only a few PSI of dP ... even at high flow rates. At lower normal flow rates for most cars on the road crusing arond at 2500 RPM (like 5 GPM), the dP vs flow is very small between oil filters. I'm wondering it LSJr has even seen one dP vs flow perormance curve of any oil filter.

Thread 'The Myth of "Flow Over Efficiency"'

Aug 22, 2025

The phrase often used that "Lower efficiency oil filters favor flow over efficiency" has been used here for a long time. The misconception seems to be driven by the idea that lower efficiency oil filters must "flow better" because if they are lower efficiency then the media must not be as "tight" (full of holes), and therefore they must "flow better". That can be a factor, but in reality it depends on many factors in the overall design of the media. When talking about oil filter flow performance on an engine using a positive displacement (PD) oil pump, the term "flows better"...

• ZeeOSix
• Replies: 44
• Forum: Engine Oil Filters

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[ZeeOSix]

If my guess is right the problem with Wix is they do not like to give out data. At one point they wouldn’t provide us efficiently ratings on the XP because they were “proprietary”.

Yep, I still remember that phone call where I asked what the efficiency of the Wix XP was and the guy said it was "propriatary". I asked if it was developed by NASA for a sercret Gov't program, lol.

 

[ZeeOSix]

I sent the same exact question to Fram and K&N technical support. No response yet.

Send the question to Purolator & Mann+Hummel since they wrote a paper about it. Of course you'll get a canned response from the robots working the phones. Ask for a real engineer's response.

 

[ZeeOSix]

My strictly amateur, non-professional-engineer thought is that the bypass valve kicks in when the filter's flow is restricted to a point where the engine is no getting enough oil.

The bypass valve is also to ensure the oil filter doesn't get damaged from too much dP. If an oil filter has a 23 PSI byass valve, the media and center tube better be able to take the dP constantly with a safety margin. And when the bypass valve opens, the majority of the oil is still flowing through the media unless the filter is super clogged with debris instead of the bypass just opening from thick oil or a burst of high RPM driving.

 

[ZeeOSix]

This statement from Todd the Purolator engineer in his email response of:

Means this: At 20u, this filter would start out at 90% efficiency when new, and the efficiency would go down to 60% when fully loaded. So the ISO efficiency would be 75% @ 20u.

 

[ZeeOSix]

And here's some more oil filter ISO 4548-12 efficiency testing, and all showed an efficiency loss with loading, just like Ascent's ISO efficiency testing showed. Disregard the metal mesh filters - read the article about why they behaved like they did.

If Wix actually has an ISO test lab and ran the test, they too would see oil filters losing efficiency.

https://www.kitplanes.com/oil-filter-testing/

Summary of the efficiency testing. My calculation of the efficiency at the end of the test run is shown on the side of the table for the Wix (64% @ 20u) and Champion filters (12% @ 20u).

 

[oil pan 4]

What did you expect when you contacted a customer service agent? Did you think they also were a qualified filtration engineer or tenured lab tech, who just happens to moonlight on the phone lines and/or as a chat bot?

The answer you got reads like a combination of marketing hype and AI response to me.

Makes my clanker sense tingle.

 

[ZeeOSix]

Here's a study done by Fram in 1965, and even back then they concluded - after they stopped clinging to the "cake theory model" and did their own testing - that oil filters got less efficient with debris loading.

 

[4wd]

Here's a study done by Fram in 1965, and even back then they concluded - after they stopped clinging to the "cake theory model" and did their own testing - that oil filters got less efficient with debris loading.

View attachment 319826

View attachment 319827

I would think cake theory mainly applies to large filters designed to use a special pre coat powder like DE - used by pool, wine, and oil industries …

 

[ZeeOSix]

"Cake theory" works for some filters like air filters and other types that have relatively low flow velocity and a very small dP across the media, like in air filters. That typically doesn't fit an oil filter unless it was gigantic enough with a crazy amount of media area to bring the flow velocity and dP way down.

If you setup an oil filter to filter dirty oil with the flow driven just with gravity it would probably build a better cake layer, and also not shed debris (and therefore be more efficient) because the velocity and dP is not much over zero. Obviously "cake theory" didn't work in any of the oil filters ISO efficiency tested as shown in these discussions because they have way more velocity and dP, and therefore shed debris to some extent based on the design and performance of the media.

 

[Pablo]

He meant to say efficiency changes with use.

 

[ZeeOSix]

But got the direction of change in the wrong direction, lol.

 

[Zee09]

Wix schmix

 

[4wd]

"Cake theory" works for some filters like air filters and other types that have relatively low flow velocity and a very small dP across the media, like in air filters. That typically doesn't fit an oil filter unless it was gigantic enough with a crazy amount of media area to bring the flow velocity and dP way down.

If you setup an oil filter to filter dirty oil with the flow driven just with gravity it would probably build a better cake layer, and also not shed debris (and therefore be more efficient) because the velocity and dP is not much over zero. Obviously "cake theory" didn't work in any of the oil filters ISO efficiency tested as shown in these discussions because they have way more velocity and dP, and therefore shed debris to some extent based on the design and performance of the media.

I have 60 SF to filter water at 50 gpm …
That thing is bigger than my motor, never mind my FS10575

 

[JohnnyG]

The bypass opens when the filter becomes too clogged to flow sufficiently, ensuring the engine isn't starved of oil. Note that even when the bypass is open, the majority of the oil is still flowing through the filter media. (unless it's just that clogged) If the bypass rating is 12 psid, then it will open when the pressure drop across the filter is 12 psid. When the psid falls below that, the valve shuts. The oil pressure entering the filter could be 100 psi but if the pressure after the filter is 89 psi, that's 11 psid and thus that valve is shut. When bypassing, that psid will remain at 12 psid with only enough oil bypassing to keep it there. As the filter becomes more clogged/restrictive, more and more oil will be forced through the bypass.

Also note that bypass events are rare, even with a moderately clogged filter. It can open with a new filter if the viscosity is high or low enough to significantly impact oil flow through the filter and the engine.

Of course I knew all that, but the responses to the OP's post made it sound like an oil filter would NEVER get clogged.

 

[Panda87]

I have 60 SF to filter water at 50 gpm …
That thing is bigger than my motor, never mind my FS10575

Same, the three canisters I use to filter my home’s water are 2’ long each. I pre-stage with a 40um sediment metal mesh filter, followed by a finer sediment main polyphosphate, followed by an activated carbon block and lastly a kinetic degradation fluxion filter. It’s a massive assembly, but yours sounds even more massive!

Edit: Meant to add, look at the difference of a new PHO filter versus the one in use for a year at the right side of the filtration assembly. The canister housing is clear so you can see what’s getting caught.

 

[oil pan 4]

Of course I knew all that, but the responses to the OP's post made it sound like an oil filter would NEVER get clogged.

I've cut open oil filters with thousands of hours on them that weren't clogged.
They'll clog eventually, way beyond a sensible OCI. Like way beyond several OCIs.

 

[ZeeOSix]

Here's a Machinery Lubrication article about oil filters. Note the part where they talk about "channeling" (shown below), which is basically what happens when the filter gets a surge of flow and the resulting rise in dP across the media, like if you were driving down the road cruising at 1800 RPM, then suddenly floored it and went up to redline. The media design will determine how much debris is released as flow and dP increases - and also determines how much an oil filter will shed as it loads up as seen in the ISO efficiency test data. This shedding due to flow and dP increases described below is on top of the filter decreasing in efficiency as it loads up.

https://www.machinerylubrication.com/Read/29396/oil-filter-anatomy

Here's a video (first video in the post link below) that shows this phenomena. They also mention efficiency decrease over time (ie with loading), which is seen in the ISO 4548-12 test data.

J

Post in thread 'Metal Fiber Filter Medium'

Aug 29, 2024

What is the single and multi-pass efficiency of this media?


Does the media need to be returned to the manufacturer to be cleaned or could it be cleaned by the end user?

The efficiency is the same as with glass fiber media. Check out this video on Youtube from my previous company
It shows a glass fiber element breaking down during dynamic testing. Then a metal fiber element is tested. You can see that it does not break down. This is why the Army helicopter hydraulic systems cleaned up so quickly and stayed clean. The Army saves over $50M per year now in...

• JMothersbaugh

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[ZeeOSix]

People who believed the Earth was flat needed to be told 50 different ways with proof that it wasn't because misconceptions are hard to break, lol. What's your technical input to the subject matter?

 

[TiGeo]

People who believed the Earth was flat needed to be told 50 different ways with proof that it wasn't because misconceptions are hard to break, lol. What's your technical input to the subject matter?

None. That's why I just read along and post memes. At some point soon, LSJR will likely address this apparent error on his part is my guess. My non-technical take? He has some "real world" information/data from his dyno oil testing and/or UOA testing that he is basing that comment on...or maybe not. Meanwhile, I wonder what the total post count increase has been across BITOG based on that one comment he made. It seems to be THE hot topic on the 'tog right now which by the SOPs of the MLOB, requires a BINGO card.