Wix re efficiency increasing with use

[mojoe]

Me to TechService@wix: Do oil filters for cars increase in efficiency, up to a point, as they load with use? I know that air filters do, and I just wondered if the same principle applied to oil filters.

Wix Tech Service:
Hi mojoe,
All filters increase in filtration as they capture dirt and debris. There is a fine line when it comes to oil filters as there is a bypass valve in the system.
The bypass valve will open when the oil is too cold and thick to pass through the media and also when the filter is stopped up with dirt.
Oil has to get back to the engine regardless of whether it can get through the media or not. This is the reason why oil change intervals must be done on time.
Dirty oil , grit and grime will over time shorten the life of an engine by wearing components of the engine out prematurely.


Thank you,

Mann+Hummel Product Information
Product Information (800) 949-6698)

I will follow up and ask about ISO 4548-12. The confusion and misconceptions are incredible. A lot of people are obviously unaware of some important information.

 

[dnewton3]

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.

 

[kschachn]

This is a concurrent thread where you may find additional discussion:

Thread 'LSJr Interviews Containing Oil Filter Efficiency'

Jan 14, 2026

LSJr is reiterating his opinion on filter efficiency improving with loading. He says particles that have already been captured are attracting other like particles (iron attracts other iron particles, etc.) & that's what makes the filter more efficient.

This first video is lengthy but gives some insight on his background, the filter remark is at 43:20:



This next video is shorter & a more detailed account of his career after leaving Total Seal. Oil filter remarks are at 7:20 & 8:50:

• garageman402
• Replies: 67
• Forum: Engine Oil Filters

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[mojoe]

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.

You could be right, but I specifically addressed this to technical service. Sure, it may be a canned AI response, but you gotta start somewhere, and I figure there are some people at Wix who know the answers to these questions. No harm in asking, right?

 

[mojoe]

This is a concurrent thread where you may find additional discussion:

Thread 'LSJr Interviews Containing Oil Filter Efficiency'

Jan 14, 2026

LSJr is reiterating his opinion on filter efficiency improving with loading. He says particles that have already been captured are attracting other like particles (iron attracts other iron particles, etc.) & that's what makes the filter more efficient.

This first video is lengthy but gives some insight on his background, the filter remark is at 43:20:



This next video is shorter & a more detailed account of his career after leaving Total Seal. Oil filter remarks are at 7:20 & 8:50:

• garageman402
• Replies: 67
• Forum: Engine Oil Filters

• 
• 
• 

Thank you - I've seen that.

 

[GW.]

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.

 

[mojoe]

Lake has a close connection with Wix and has done a couple oil filter vids. 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.

Could be - I have no way of knowing.

 

[GW.]

Could be - I have no way of knowing.

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”.

 

[mojoe]

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”.

Understood - Thank you.

 

[RDY4WAR]

The only data I've seen on this, published by a filter brand or independent testing, shows oil filtration dropping with use/loading. This is logical given the density of the oil, the flow rate, and viscosity. As the filter clogs, the pressure differential will increase until it reaches the critical pressure that forces the bypass open. The same volume of oil is forcing it's way through less and less media area which is why the pressure differential is increasing. The oil is going to find it's way through, like he said, which means pushing pleating aside and deforming the media, if necessary. Even once the bypass opens, there's still at least 12 psid (or whatever the bypass spring rating is) acting on the media with only the excess above that being bypassed. You can't tell me that the filter is more efficient at 12 psid than it is at 3-5 psid. I'm calling total BS on that.

 

[Fair enough]

They are right about most of it, but oil flowing forcefully through a tubing system is far different than much lighter air hitting an air box that is many times the area of a throttle body opening. The particles they travel with are going to be pressed into the media very differently.
IN MY OPINION.

 

[JavierH19]

"intellectual horsepower" "science not speculation" so much overcompensation.

 

[mojoe]

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”.

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

 

[JohnnyG]

If the WIX response is wrong, what IS the purpose of the bypass valve?

 

[Geekhead]

My opinion is the quality of the oil and change interval matters far more than filter efficiency. On all my cars I just use dealer/OEM filters and engine wear /oil consumption never was a factor in when I disposed of any high mileage car. Most went 15 years, 1 went 24 years and most exceeded 175,000 miles.

 

[mojoe]

If the WIX response is wrong, what IS the purpose of the bypass valve?

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.

 

[rstsco]

If the WIX response is wrong, what IS the purpose of the bypass valve?

Because dirty oil is better than no oil.

 

[gfh77665]

And in a heartbeat... Queue up LSJ.

Actually a microsecond.

 

[RDY4WAR]

If the WIX response is wrong, what IS the purpose of the bypass valve?

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.

 

[ZeeOSix]

I contacted Purolator back in 2011 and had many email communications with a couple of real engineers there and their manager CCed in the emails. Back then, their manager actual sent the questions to the actual engineers at Purolator.

Here's the email response I got when I asked if oil filters get more efficient with loading. This is where the whole "hockey stick" efficiency curve due to loading comes from. It's the term the Purolator engineer used in his response to describe the shape of the efficiency vs loading curve. I talked about this in this forum way back since 2011 (the threads and posts should still be around somewhere), and it's still something that people don't seem to believe.

I don't believe the canned answer that Wix gave. They are making the same leap that LSJr is making between air and oil filters. Ask them to have an actual Wix filter engineer respond to the question with some real test data like Purolator did.

This came out years later from a technical paper that Purolator/Mann+Hummel published showing how oil filters lose efficiency with debris loading. This is the efficiency "hockey stick" curve the Purolator engineer Todd was describing. We also have seen this in all the filters that Ascent tested, except Ascend cut off the test runs at 8 dP above the new filter's dP before the filter totally clogged to get the sudden rise in efficiency at the end of filter life.