Oil Filter......Flow vs. Filtration?

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I'll take filtration. Unless they forget to drill holes in the center tube, I don't think flow will be an issue.
 
Originally Posted By: dnewton3
I invite you to disucss in detail, how you believe the Ford study relates to "clean" oil. I do not believe it does.

I think the definition of "clean oil" is the disconnect in this discussion. I suspect that you and I are in agreement that "clean oil" and "new oil" are not the same things.
 
Originally Posted By: FetchFar
dnewton3, The SAE papers speak for themselves. I'll take those careful engineering studies over your ramblings any day.



One man's ramblings is another man's clear, thoughtful and detailed explanation. To each his own.

I would agree; they do speak for themselves.

And I would assume that you've spoken for yourself. In the face of my challenge to support your position with detailed analysis of the studies, you've acquiesced. You've given no substantial reason for me to believe that you’ve read them, nor are you willing to discuss them, nor are willing to debate the applicability to the real world situations.

Allow me to "raise the ante" and support my side of the discussion ...

First of all, we should agree that there are two filters on the typical engine; an air filter and an oil filter. The air filter generally deals with silicate ingestion; the oil filter deals with soot generated from the engine, as well as anything ingested that would pass into the lube system, and wear particles themselves.

We need to understand how a "normal" engine ingests contamination via air filtration. I offer Jim Allen's excellent explanation here: http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3229015/5
Depending upon how often you change air filters, you can significantly alter the ingestion rate. Just as with any filter, frequent changes actually REDUCE the efficiency. So I'm going to make some assumptions upon average folks and not anal-retentive BITOG over-achievers ...
Using Jim's data, I'll estimate that approximately .75 oz of dust ingested over perhaps 30k mile air filter change intervals. That is equivalent to about 21 grams of dust.

In regard to the GM filter study, I call into question not the validity of the study itself, as I understand the premise of its intent, but rather the application of the study to real world use of filters in everyday lives of millions of pieces of equipment. I'll go over my contentions one at a time:

1) Contamination loading:
In the GM study, they dumped 50 grams of fine AC dust into the sump every hour, for 8 hours. (Page 2, first paragraph). That is 400 grams of contamination over the 8 hours of testing. They did this to "accelerate" the wear attributed to differing filtration levels. For us to understand how much this relates to the "real world", we have to understand how much dust would enter an engine during normal use, and then figure an estimated mileage duration that would infer, presuming average air filter changes and loading. Using Jim's data, we can use the average of 21 grams of dust every 30k miles. Considering GM induced 400 grams of dust in the entire test that would be roughly equivalent to 19 air filter changes. Multiply that FCI quantity by the miles per change and you can see that the contamination loading was equivalent to 570k miles of typical road use dirt ingestion. Yes - you read that right; the sump in the GM study suffered Five-Hundred-Seventy Thousand miles of contamination loading based upon typical air filter changes. As I already stated, this is somewhat dependent upon your air filter change interval, etc. While we could debate this exposure duration, let us just agree it’s a LOT of contamination represented by a LOT of miles. Whether you think it’s 400k miles, 500k miles, or 600k miles is of no real consequence to me. Most folks NEVER own and operate a vehicle or other piece of equipment this long. This represents a HUGE amount of dust ingestion; more than a lifetime for most folks.

2) Oil sump changes:
In the GM study, they never changed oil for the duration of the test. While they did filter it, they never changed it, relative to each filter used. Each sump lasted 8 hours for each filter trial. Given that the sump endured an approximation of 570k miles of contamination ingestion, the OCI duration equivalent in terms of ingestion loading was also 570k miles. That does NOT mean the other contributors to contamination were equal; there is no reason to believe that soot loading was very high as only 8 hours were run per test. Soot loading is a factor of incomplete combustion byproducts; that is not an issue here because the engine simply didn’t run long relative to the real world OCI. In other words, the engine did not burn 570k miles worth of fuel; it only burned 8 hours of fuel, so the soot loading would have been very low relative to the ingestion of the fine dust. But the "age" of oil in terms of the variable manipulated (fine AC dust loading to affect wear) was prolifically long to say the least. A "typical" person would perhaps OCI every 5k miles, and would have seen 114 oil changes relative to the contaminant loading. To put that in perspective for 8 hours duration, they would have changed oil every 4.2 minutes to represent "normal" OCIs in terms of contamination. But they never changed oil at all. And so the sump loading of contamination was allowed to become extremely prominent to say the least. The overall presence of particulate was WAY more than a typical sump would ever see even in a worst case scenario. Why do we want to understand this? Because, while the filtration was manipulated ABOVE 15um, the net result was that a huge amount of small particulate stayed in the sump for the entire 8 hours! Any particle that was 5um, 7um on up to 10um was able to continually circulate repeatedly with no capture at all! Those particles (and there were certainly a LOT of them according to the data) just floated along indiscriminately and did damage while no filter was able to remove them. Therefore, because they didn’t change oil, they never got rid of the small particles (5-10um) that do a lot of damage. They dumped in 500k miles of dust, and then never addressed particles that are capable of damage below 10um. That 10um size is important and will be discussed further down; see the * … In short, because they never did an OCI for the equivalent of 500k+ miles of dust ingestion, the UOA wear data represents a LOT of metals due to smaller particulate never leaving the system; never at all.

3) Add-pack condition:
In the GM study, because they heavily dosed with dust, thereby creating artificial wear rates over one R-E-A-L-L-Y_L-O-N-G OCI, the additive package was greatly overwhelmed. The anti-agglomerates and detergents were so hopelessly over-run that I cannot really find a way to describe or define how it could be measured. Let it suffice to say there was no hope that the additives would have been able to handle the loading. Referring to the OCI duration in point #2 above, a 570k mile OCI with only oil filter changes isn’t representative of real world add-pack health. Admittedly, silica is not directly controlled by dispersants, but they can alter the ability of the add-pack to function when their concentration is so grossly high. I don’t know of any SAE study or ASTM test that can show us a definitive cut-off point or direct correlation, but I highly suspect the 570k miles of equivalent silica is “over the top” to say the least. I’ll note this as well; because the test was only run for 8 hours, we can exclude soot contribution to the loading of particulate; the engines simply did not run long enough to really produce a significant amount of soot. Eight hours is only one full day’s drive, after all. Overall, this topic is moot in terms of wear contribution. And so, the VAST majority of wear is only attributed to the equivalent of ingestion wear and not hydrocarbon byproducts.

4) Filter efficiency:
In the GM study, all filters were rated at 98% efficiency (a fairly good rate overall) at the desired particulate range as the starting point. They tested eight (8) filters total; four for a diesel engine and four for a gasoline engine. The four diesel filters were rated at 40um, 15um, 8.5um and 7um; all rated at 98% first pass. The gasoline engine filters were rated at 40um, 30um, 25um and 15um, again 98% first pass. They used the 40um filter as a “baseline” for performance. Now, we need to understand that today’s “typical” filter is nowhere nearly that bad in terms of performance. Many filters are available that can be 98% at 25um or maybe even 20 um, some are even 99% at 20um. Therefore, the “baseline” of the “improvement” in wear reduction really isn’t based upon a realistic starting point. We can easily get a decent filter that is 95-99% efficient at 20um from any manner of brands. The use of a 40um filter for a starting point may or may not have been reasonable back in 1988 when the study was posted, but it’s not anywhere reasonable today as most filters are much more efficient than that. So the claim by GM that filtration can reduce wear by “70%” is biased in that they started from such a poor state to begin with. That “70%” wear reduction rate was based upon contrasting the 40um filter to a 15um filter in the gas engine application. They showed a 70% reduction of wear going from the worst to best filter at 98% efficiency. But in today’s world, it would be easy to start at 20um as “baseline”. And frankly, you’d struggle to find a filter that would be so efficient at a significantly smaller size anyway in terms of full-flow performance; I’m not aware of a filter that is commercially widely available that would be 98% at 15um off the shelf.

* Also, they noted that while single pass filtration efficiencies can predict relative wear data shifts, multi-pass filtration can also narrow performance disparity when averaged over the life of the test. And I quote:
Even though filter (A) was rated at 40 micron, it effectively removed particles down to 10 micron. To do this, recirculation of the oil through the filter was required.” In other words, use your filter and the efficiency increases! Just as Jim’s data shows in air filtration, that same concept applies to oil filtration. The longer they used the 40um filter, the better job it did, and to a point where at 10um, there was a convergence of filter efficiency between all filters tested!!! To quote the study:
Note that concentrations converged above 10 micron for all filters. (page 4, fourth paragraph).
In essence, if you use a 40um filter long enough, it will perform as if it were a 15um filter as the pores close down. And any particulate smaller than the typical pore size after multi-pass, will pass ANY filter media anyway. This is why I state that once a filter is appropriately defined in terms of efficiency and pore size, using a “better” filter really does not show any real-world tangible wear reduction. Here is why this happened, so read VERY CLOSELY and UNDERSTAND the cycle of the test protocol.

- They dump in 50 grams of dust (equivalent to 70k miles of ingestion all at once!), and this is done once every hour
- Wear escalates because the FIRST SEVERAL PASSES of the oil allows a lot of garbage to continue around in circulation and generate wear in the engine
- As the media loads up, REGARDLESS of the starting pore size rating, the filter essentially loads to a point where ALL filters tested see performance converge above 10um

Why is this important to understand? Because the filters with larger pore sizes allow a lot more stuff to circulate in the first few passes, causing a LOT of wear in the first few minutes of each hour’s “ingestion”. But after those first several passes, the filters will all settle to a reasonably similar pore size with good efficiency. The wear spikes at the front end of the contamination load in the test, and then it falls dramatically after a few minutes because the media of ALL filters becomes loaded to a point where 10um pores are about the only thing remaining! The filter was ONLY changed once the dP would approach bypass. Until then, the filter just continued to load up and all filters loaded equally well after the first few minutes.

This is why I state that using a “better” filter really does not reduce wear in a tangible manner for the average garage engine in a typical application. While the first pass efficiency may result in a tiny fractional difference, the multi-pass effect over 5k-15k miles is moot because all the filters essentially load up equally. And because we don’t “spike” dirt into the engine (the air filter stays in place and the soot production is a low constant), there will never be a cause for wear to escalate arbitrarily.

(NOTE: The ONLY time we typically see wear escalate is at the front end of an OCI, and that is because of the removal of the tribochemical barriers by the add-pack, as established and proven in the Ford/Conoco study 2007-01-4133. It has nothing to do with filtration in this regard.)


How would all this relate to the real world? Well – if you’re inclined to “spike” your engine with dirt by arbitrarily removing the air filter for a few weeks and driving through a dusty bean field all day long, then this would roughly be a reasonable equivalent. Your wear would escalate dramatically until your oil filter would capture what your missing air filter did not. And don’t forget to not change oil for while you’re at it!


Here’s what I do like about the GM study: they did show a reasonable correlation between wear data in UOA analysis and wear data as measure by % weight loss concentration. This is actually one part of the study I like and believe has merit, although it is only mentioned in passing. They did both methods, as well as relied upon former studies also linking wear data tracking methods to show that UOAs can be reasonably used to track relative wear conditions. They also noted that physical measurement methods are prone to errors; you cannot disassemble an engine multiple times during a test and expect repeatability as thing like bearings and such will be altered by the removal and reinstallation. However, changes in weight of components had a reasonable correlation to percent shift in UOA spectral analysis; I agree with this!


And so, I contend that the GM filter study was a lab test that did prove what it set out to prove. It showed a reasonable correlation of wear reduction to filtration pore size at a stated efficiency relative to the first few passes. But that entire test was heavily biased towards accelerated wear to a point where no “normal” equipment would ever be allowed to run. The test bordered on, in my opinion, absurd. I would liken such treatment to abuse or neglect. Some would contend that they did this to “accelerate” the wear to simulate 500k+ miles of use. OK – I might agree with that. But again, they did not also do the things in that simulated 500k miles which ALSO go along with wear control. They didn’t change oil at a reasonable frequency; they didn’t change oil at all! Therefore the wear they induced was ONLY applicable to someone who runs a 500k mile OCI, and only manages the oil filter to a point where the component is changed only when the dP across the media is at 10-20psi (a point at which most any normal filter would already be in constant bypass due to complete media blinding anyway) ….

Here is a quote I agree with, but only because they confine their statement well:
By comparing filter bench test performance with the engine wear data, it becomes apparent that a filter’s single pass efficiency correlates very well with its ability to control abrasive engine wear.” (page 5, paragraph 1)
Why do I agree? Because they state it related in SINGLE PASS scenarios. And this is proven true when you never change oil and also dump a slug of garage into the sump!
But if you change oil with normal frequency, and maintain a reasonable air filter situation, and you allow the oil filter to control contamination via MULTI-pass, you’ll NEVER see this kind of disparity between filters.


Do you see the difference between what they did in their “test” and what the real world does in the garage?


And so I disagree with anyone who says that study has merit in the real world. No one I know of, nor any maintenance program I’m aware of, uses such parameters to run their equipment.

And GM even acknowledged this on page 2, in the last paragraph …
Used oil analysis from engines in the field will not typically show such a clear correlation since wear metals generated between oil changes will be a much lower concentrations.
In other words, they know that because OCIs were negated AND contamination was grossly overdone in their test, simple routine maintenance will not ever result in such wear rates, therefore the filter disparity will never materialize. So GM went to great effort to correlate UOA wear data with weighed component wear data, and then clearly states that real world usage wear data will never show filter performance differences because wear is just never, ever that bad in normal circumstances.

In short, I agree that the test proved what it set out to prove. What I disagree with is that the study has any valid application to real world situations. And anyone who states such will have to prove to me just how they think 500k mile OCIs with single-pass base-rated at ol-skool 40um filters is applicable to today’s equipment management.

I welcome anyone’s interpretation that would otherwise counter mine for discussion, but again I ask that if you want to convince me I’m wrong, please bring PROOF and show how your position is relevant to REAL WORLD applications, because this study most certainly isn’t. Please be willing to discuss how and why you see merit where I do not. Don’t just revert to a position of “because they said so …” What that outwardly indicates to me is that one has not read, and/or does not understand, the basic principles and limitations of that GM filter study.


The papers have spoken, you have spoken, and I have spoken.
Now the folks can decide for themselves.
 
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I sound like I disrespect dnewton3, so I apologize for that. I do have a bias toward real-world engine testing though, which makes me discount theoretical discussions, however cool or basically valid they are.
 
Good to see that mine aren't the only posts that are popcorn worthy on this board. At least in this one there's only impassioned discussion, and no extraneous/irrelevant picture posting, consuming bandwidth. But I digress.

To the topic, when someone can prove to me that flow is a significant factor in standard passenger car use, I might give it some consideration. Until then I'll take filtration first. And while there may be debate, as shown in this thread, as to whether finer filtration will reduce wear, as Jim Allen has said here on the subject, there's nothing lost by having it.
 
Originally Posted By: sayjac
. Until then I'll take filtration first. And while there may be debate, as shown in this thread, as to whether finer filtration will reduce wear, as Jim Allen has said here on the subject, there's nothing lost by having it.


Agreed, in fact I tend to side with those who favor low-micron filtration, such as the claims made at microgreenfilters.com where they show how getting the finer stuff out, down to around 4 microns or so, is beneficial. They claim to have done fleet studies, although I'd like independent corroboration of it all. I guess fleet managers have been convinced its the way to go to save $$ on maintenance by getting better filtration.
 
Originally Posted By: sayjac
Good to see that mine aren't the only posts that are popcorn worthy on this board. At least in this one there's only impassioned discussion, and no extraneous/irrelevant picture posting, consuming bandwidth. But I digress.

To the topic, when someone can prove to me that flow is a significant factor in standard passenger car use, I might give it some consideration. Until then I'll take filtration first. And while there may be debate, as shown in this thread, as to whether finer filtration will reduce wear, as Jim Allen has said here on the subject, there's nothing lost by having it.


I didn't see this coming when I started this Thread! But, it sure has been an interesting read......

I will say that I have settled on Wix filters at the moment. They are a happy medium and made really well! I just purchased 6 Wix 57055 and 6 57356 filters.
 
Originally Posted By: Cooper

I will say that I have settled on Wix filters at the moment. They are a happy medium and made really well! I just purchased 6 Wix 57055 and 6 57356 filters.


Medium nothing, those are premium filters, glass fiber plus cellulose blends. You chose well. Might as well use good ones, no reason not to.
 
Originally Posted By: sayjac
To the topic, when someone can prove to me that flow is a significant factor in standard passenger car use, I might give it some consideration. Until then I'll take filtration first.

I would agree with that. I've never really bought into the argument that any off the shelf filter when used in its specified application is restrictive. That's never been an issue for me. But, to be clear, while I "prefer" a higher filtration efficiency, I don't think that any of the big names we see on the shelf or from OEMs aren't "good enough," either.

For example, I like the P1's 99.9% rating, let's say. Considering the difficulty in finding them, I'm not going to chase them, either. Flow is good, too, but I couldn't be bothered with a racing filter, either.

If one is really worried about filtration, one can set up bypass filtration and all sorts of goodies. It's all pretty cool and interesting stuff, but one has to decide whether or not it's worth it in one's own use.
 
Originally Posted By: FetchFar
The SAE papers speak for themselves. I'll take those careful engineering studies over your ramblings any day.


Originally Posted By: FetchFar
I do have a bias toward real-world engine testing though, which makes me discount theoretical discussions, however cool or basically valid they are.


I don't really understand how you can make those two statements in regard to the same SAE study by GM.
You accept the GM study as "careful engineering" but then you have a "bias toward real-world testing"?
As I clearly have explained, that GM study is about as far from reality as one could get, unless your typical day includes dumping 70k miles worth of contamination into your engine every hour, and never changing oil ...

I never took your comments as personal affronts; you don't owe me any apology, but it is very civil of you and I thank you for the offering. However you do owe us some form of explanation as to how you can make those two opposing statements above in context to the GM study. You have yet to show me how my "ramblings" are without merit, and yet a heavily biased and unrealistic test is worthy of your respect. My contention has always been that the GM study has no applicability to real-world situations. How is it that you claim to favor real world data, but discount my review of the GM study, and then never rise to the duty of explanation? I have no objection if you disagree with me; many here do. But I ask that if you don't see things as I do, please explain how any why. After all, if you're right and I'm wrong, I just might be able to learn something new!

I, too, favor the information of results (outputs) over predictors (inputs) all the time; it is my penchant in my job as a QC statistical analyst. I, too, appreciate real-world data over lab testing. While I most certainly do see merit and validation in lab testing to exhibit distinct differences of subject matter, they are often targeted (on purpose) with a bias to bring some feature or characteristic to light. Real world use will typically show us how things are, not how someone wants them to be. If it's real world data you seek, then read my article:
http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/
I have well over 10,000 UOAs in my database; I've simply stopped counting at this point. I do continue to collect data, but I no longer quantify the totals for the sake of hapless knowledge. What we can take from this data I put together is the fact that regardless of brand and grade of oil, despite the use or eschewment of premium filters, most all equipment soldiers on with no complaints. Macro data shows that "normal" is just that; it's typical and the V-A-S-T majority of requipment works just fine with everyday products. Only when one ventures WAY off the reservation do you need some alternate form of extra protection. The micro-data example in my article shows that premium products did absolutely nothing to alter wear in an appreciable manner under the typical operating conditions.


Allow me to bring this full circle, and home again ...
Both flow and filtration in any typical filter are way more than adequate to achieve the safe, healthy operation of one's stuff. My real world data shows that despite all the hand-wringing and sleepless nights BITOGers go through, using any properly qualified product will suffice to make the equipment last longer than most would care to own it.

Allow me to quote myself from my first post in this thread:
Originally Posted By: dnewton3

- Do you, as the typical BITOGer, run 20w-50 in your fuel-efficient 4-banger, and then stomp on the loud-pedal to WOT for minutes on end immediately after starting your engine in the Yukon in winter?
- Do you, as the typical BITOGer, run your engine with no air filter, change oil every 100k miles, while leaving the oil filler cap off, and only changing oil filters every 20k miles or so?
If these conditions don't apply to you, then the topic about flow vs filtration is moot. Period.

In my opinion, many of you guys worry too much about silly little nuances that don't ever manifest into anything in the real world.


I can articuably describe why the GM filter study is useless in the real world.
I can distinctly show how thousands upon thousands of engines operate well with all manner of products, where neither flow or filtration matter above the other.

Rather than pose a question as to why we should "choose" between flow and filtration, perhaps the better question is this:
Can anyone show clear, definitive proof that flow and filtration are mutually exclusive and cannot provide proper protection without negative effect of the other?

The entire topic of this thread, that of having to choose one operational parameter over the other, is, frankly, stupid.
The more I think about it, the more I owe everone else an apology.
I'm sorry I ever got involved in such an inane topic in the first place.
grin.gif
 
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Originally Posted By: Garak
Originally Posted By: sayjac
To the topic, when someone can prove to me that flow is a significant factor in standard passenger car use, I might give it some consideration. Until then I'll take filtration first.

I would agree with that. I've never really bought into the argument that any off the shelf filter when used in its specified application is restrictive. That's never been an issue for me. But, to be clear, while I "prefer" a higher filtration efficiency, I don't think that any of the big names we see on the shelf or from OEMs aren't "good enough," either.

For example, I like the P1's 99.9% rating, let's say....

Completely agree. I'm not fanatical about it, I've used many a filter that didn't have a super published efficiency rating with no concern. But all other things being equal my preference would be toward the higher efficiency rated filter.

I guess the bigger point was, based on reading this board over the years filter flow is so insignificant in pc use, that it's not even worth mentioning imo.
 
Originally Posted By: dnewton3
Originally Posted By: FetchFar
dnewton3, The SAE papers speak for themselves. I'll take those careful engineering studies over your ramblings any day.



One man's ramblings is another man's clear, thoughtful and detailed explanation. To each his own.

I would agree; they do speak for themselves.

And I would assume that you've spoken for yourself. In the face of my challenge to support your position with detailed analysis of the studies, you've acquiesced. You've given no substantial reason for me to believe that you’ve read them, nor are you willing to discuss them, nor are willing to debate the applicability to the real world situations.

Allow me to "raise the ante" and support my side of the discussion ...

First of all, we should agree that there are two filters on the typical engine; an air filter and an oil filter. The air filter generally deals with silicate ingestion; the oil filter deals with soot generated from the engine, as well as anything ingested that would pass into the lube system, and wear particles themselves.

We need to understand how a "normal" engine ingests contamination via air filtration. I offer Jim Allen's excellent explanation here: http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3229015/5
Depending upon how often you change air filters, you can significantly alter the ingestion rate. Just as with any filter, frequent changes actually REDUCE the efficiency. So I'm going to make some assumptions upon average folks and not anal-retentive BITOG over-achievers ...
Using Jim's data, I'll estimate that approximately .75 oz of dust ingested over perhaps 30k mile air filter change intervals. That is equivalent to about 21 grams of dust.

In regard to the GM filter study, I call into question not the validity of the study itself, as I understand the premise of its intent, but rather the application of the study to real world use of filters in everyday lives of millions of pieces of equipment. I'll go over my contentions one at a time:

1) Contamination loading:
In the GM study, they dumped 50 grams of fine AC dust into the sump every hour, for 8 hours. (Page 2, first paragraph). That is 400 grams of contamination over the 8 hours of testing. They did this to "accelerate" the wear attributed to differing filtration levels. For us to understand how much this relates to the "real world", we have to understand how much dust would enter an engine during normal use, and then figure an estimated mileage duration that would infer, presuming average air filter changes and loading. Using Jim's data, we can use the average of 21 grams of dust every 30k miles. Considering GM induced 400 grams of dust in the entire test that would be roughly equivalent to 19 air filter changes. Multiply that FCI quantity by the miles per change and you can see that the contamination loading was equivalent to 570k miles of typical road use dirt ingestion. Yes - you read that right; the sump in the GM study suffered Five-Hundred-Seventy Thousand miles of contamination loading based upon typical air filter changes. As I already stated, this is somewhat dependent upon your air filter change interval, etc. While we could debate this exposure duration, let us just agree it’s a LOT of contamination represented by a LOT of miles. Whether you think it’s 400k miles, 500k miles, or 600k miles is of no real consequence to me. Most folks NEVER own and operate a vehicle or other piece of equipment this long. This represents a HUGE amount of dust ingestion; more than a lifetime for most folks.

2) Oil sump changes:
In the GM study, they never changed oil for the duration of the test. While they did filter it, they never changed it, relative to each filter used. Each sump lasted 8 hours for each filter trial. Given that the sump endured an approximation of 570k miles of contamination ingestion, the OCI duration equivalent in terms of ingestion loading was also 570k miles. That does NOT mean the other contributors to contamination were equal; there is no reason to believe that soot loading was very high as only 8 hours were run per test. Soot loading is a factor of incomplete combustion byproducts; that is not an issue here because the engine simply didn’t run long relative to the real world OCI. In other words, the engine did not burn 570k miles worth of fuel; it only burned 8 hours of fuel, so the soot loading would have been very low relative to the ingestion of the fine dust. But the "age" of oil in terms of the variable manipulated (fine AC dust loading to affect wear) was prolifically long to say the least. A "typical" person would perhaps OCI every 5k miles, and would have seen 114 oil changes relative to the contaminant loading. To put that in perspective for 8 hours duration, they would have changed oil every 4.2 minutes to represent "normal" OCIs in terms of contamination. But they never changed oil at all. And so the sump loading of contamination was allowed to become extremely prominent to say the least. The overall presence of particulate was WAY more than a typical sump would ever see even in a worst case scenario. Why do we want to understand this? Because, while the filtration was manipulated ABOVE 15um, the net result was that a huge amount of small particulate stayed in the sump for the entire 8 hours! Any particle that was 5um, 7um on up to 10um was able to continually circulate repeatedly with no capture at all! Those particles (and there were certainly a LOT of them according to the data) just floated along indiscriminately and did damage while no filter was able to remove them. Therefore, because they didn’t change oil, they never got rid of the small particles (5-10um) that do a lot of damage. They dumped in 500k miles of dust, and then never addressed particles that are capable of damage below 10um. That 10um size is important and will be discussed further down; see the * … In short, because they never did an OCI for the equivalent of 500k+ miles of dust ingestion, the UOA wear data represents a LOT of metals due to smaller particulate never leaving the system; never at all.

3) Add-pack condition:
In the GM study, because they heavily dosed with dust, thereby creating artificial wear rates over one R-E-A-L-L-Y_L-O-N-G OCI, the additive package was greatly overwhelmed. The anti-agglomerates and detergents were so hopelessly over-run that I cannot really find a way to describe or define how it could be measured. Let it suffice to say there was no hope that the additives would have been able to handle the loading. Referring to the OCI duration in point #2 above, a 570k mile OCI with only oil filter changes isn’t representative of real world add-pack health. Admittedly, silica is not directly controlled by dispersants, but they can alter the ability of the add-pack to function when their concentration is so grossly high. I don’t know of any SAE study or ASTM test that can show us a definitive cut-off point or direct correlation, but I highly suspect the 570k miles of equivalent silica is “over the top” to say the least. I’ll note this as well; because the test was only run for 8 hours, we can exclude soot contribution to the loading of particulate; the engines simply did not run long enough to really produce a significant amount of soot. Eight hours is only one full day’s drive, after all. Overall, this topic is moot in terms of wear contribution. And so, the VAST majority of wear is only attributed to the equivalent of ingestion wear and not hydrocarbon byproducts.

4) Filter efficiency:
In the GM study, all filters were rated at 98% efficiency (a fairly good rate overall) at the desired particulate range as the starting point. They tested eight (8) filters total; four for a diesel engine and four for a gasoline engine. The four diesel filters were rated at 40um, 15um, 8.5um and 7um; all rated at 98% first pass. The gasoline engine filters were rated at 40um, 30um, 25um and 15um, again 98% first pass. They used the 40um filter as a “baseline” for performance. Now, we need to understand that today’s “typical” filter is nowhere nearly that bad in terms of performance. Many filters are available that can be 98% at 25um or maybe even 20 um, some are even 99% at 20um. Therefore, the “baseline” of the “improvement” in wear reduction really isn’t based upon a realistic starting point. We can easily get a decent filter that is 95-99% efficient at 20um from any manner of brands. The use of a 40um filter for a starting point may or may not have been reasonable back in 1988 when the study was posted, but it’s not anywhere reasonable today as most filters are much more efficient than that. So the claim by GM that filtration can reduce wear by “70%” is biased in that they started from such a poor state to begin with. That “70%” wear reduction rate was based upon contrasting the 40um filter to a 15um filter in the gas engine application. They showed a 70% reduction of wear going from the worst to best filter at 98% efficiency. But in today’s world, it would be easy to start at 20um as “baseline”. And frankly, you’d struggle to find a filter that would be so efficient at a significantly smaller size anyway in terms of full-flow performance; I’m not aware of a filter that is commercially widely available that would be 98% at 15um off the shelf.

* Also, they noted that while single pass filtration efficiencies can predict relative wear data shifts, multi-pass filtration can also narrow performance disparity when averaged over the life of the test. And I quote:
Even though filter (A) was rated at 40 micron, it effectively removed particles down to 10 micron. To do this, recirculation of the oil through the filter was required.” In other words, use your filter and the efficiency increases! Just as Jim’s data shows in air filtration, that same concept applies to oil filtration. The longer they used the 40um filter, the better job it did, and to a point where at 10um, there was a convergence of filter efficiency between all filters tested!!! To quote the study:
Note that concentrations converged above 10 micron for all filters. (page 4, fourth paragraph).
In essence, if you use a 40um filter long enough, it will perform as if it were a 15um filter as the pores close down. And any particulate smaller than the typical pore size after multi-pass, will pass ANY filter media anyway. This is why I state that once a filter is appropriately defined in terms of efficiency and pore size, using a “better” filter really does not show any real-world tangible wear reduction. Here is why this happened, so read VERY CLOSELY and UNDERSTAND the cycle of the test protocol.

- They dump in 50 grams of dust (equivalent to 70k miles of ingestion all at once!), and this is done once every hour
- Wear escalates because the FIRST SEVERAL PASSES of the oil allows a lot of garbage to continue around in circulation and generate wear in the engine
- As the media loads up, REGARDLESS of the starting pore size rating, the filter essentially loads to a point where ALL filters tested see performance converge above 10um

Why is this important to understand? Because the filters with larger pore sizes allow a lot more stuff to circulate in the first few passes, causing a LOT of wear in the first few minutes of each hour’s “ingestion”. But after those first several passes, the filters will all settle to a reasonably similar pore size with good efficiency. The wear spikes at the front end of the contamination load in the test, and then it falls dramatically after a few minutes because the media of ALL filters becomes loaded to a point where 10um pores are about the only thing remaining! The filter was ONLY changed once the dP would approach bypass. Until then, the filter just continued to load up and all filters loaded equally well after the first few minutes.

This is why I state that using a “better” filter really does not reduce wear in a tangible manner for the average garage engine in a typical application. While the first pass efficiency may result in a tiny fractional difference, the multi-pass effect over 5k-15k miles is moot because all the filters essentially load up equally. And because we don’t “spike” dirt into the engine (the air filter stays in place and the soot production is a low constant), there will never be a cause for wear to escalate arbitrarily.

(NOTE: The ONLY time we typically see wear escalate is at the front end of an OCI, and that is because of the removal of the tribochemical barriers by the add-pack, as established and proven in the Ford/Conoco study 2007-01-4133. It has nothing to do with filtration in this regard.)


How would all this relate to the real world? Well – if you’re inclined to “spike” your engine with dirt by arbitrarily removing the air filter for a few weeks and driving through a dusty bean field all day long, then this would roughly be a reasonable equivalent. Your wear would escalate dramatically until your oil filter would capture what your missing air filter did not. And don’t forget to not change oil for while you’re at it!


Here’s what I do like about the GM study: they did show a reasonable correlation between wear data in UOA analysis and wear data as measure by % weight loss concentration. This is actually one part of the study I like and believe has merit, although it is only mentioned in passing. They did both methods, as well as relied upon former studies also linking wear data tracking methods to show that UOAs can be reasonably used to track relative wear conditions. They also noted that physical measurement methods are prone to errors; you cannot disassemble an engine multiple times during a test and expect repeatability as thing like bearings and such will be altered by the removal and reinstallation. However, changes in weight of components had a reasonable correlation to percent shift in UOA spectral analysis; I agree with this!


And so, I contend that the GM filter study was a lab test that did prove what it set out to prove. It showed a reasonable correlation of wear reduction to filtration pore size at a stated efficiency relative to the first few passes. But that entire test was heavily biased towards accelerated wear to a point where no “normal” equipment would ever be allowed to run. The test bordered on, in my opinion, absurd. I would liken such treatment to abuse or neglect. Some would contend that they did this to “accelerate” the wear to simulate 500k+ miles of use. OK – I might agree with that. But again, they did not also do the things in that simulated 500k miles which ALSO go along with wear control. They didn’t change oil at a reasonable frequency; they didn’t change oil at all! Therefore the wear they induced was ONLY applicable to someone who runs a 500k mile OCI, and only manages the oil filter to a point where the component is changed only when the dP across the media is at 10-20psi (a point at which most any normal filter would already be in constant bypass due to complete media blinding anyway) ….

Here is a quote I agree with, but only because they confine their statement well:
By comparing filter bench test performance with the engine wear data, it becomes apparent that a filter’s single pass efficiency correlates very well with its ability to control abrasive engine wear.” (page 5, paragraph 1)
Why do I agree? Because they state it related in SINGLE PASS scenarios. And this is proven true when you never change oil and also dump a slug of garage into the sump!
But if you change oil with normal frequency, and maintain a reasonable air filter situation, and you allow the oil filter to control contamination via MULTI-pass, you’ll NEVER see this kind of disparity between filters.


Do you see the difference between what they did in their “test” and what the real world does in the garage?


And so I disagree with anyone who says that study has merit in the real world. No one I know of, nor any maintenance program I’m aware of, uses such parameters to run their equipment.

And GM even acknowledged this on page 2, in the last paragraph …
Used oil analysis from engines in the field will not typically show such a clear correlation since wear metals generated between oil changes will be a much lower concentrations.
In other words, they know that because OCIs were negated AND contamination was grossly overdone in their test, simple routine maintenance will not ever result in such wear rates, therefore the filter disparity will never materialize. So GM went to great effort to correlate UOA wear data with weighed component wear data, and then clearly states that real world usage wear data will never show filter performance differences because wear is just never, ever that bad in normal circumstances.

In short, I agree that the test proved what it set out to prove. What I disagree with is that the study has any valid application to real world situations. And anyone who states such will have to prove to me just how they think 500k mile OCIs with single-pass base-rated at ol-skool 40um filters is applicable to today’s equipment management.

I welcome anyone’s interpretation that would otherwise counter mine for discussion, but again I ask that if you want to convince me I’m wrong, please bring PROOF and show how your position is relevant to REAL WORLD applications, because this study most certainly isn’t. Please be willing to discuss how and why you see merit where I do not. Don’t just revert to a position of “because they said so …” What that outwardly indicates to me is that one has not read, and/or does not understand, the basic principles and limitations of that GM filter study.


The papers have spoken, you have spoken, and I have spoken.
Now the folks can decide for themselves.


Fantastic post Dave, and I think the conclusions drawn by you on this study are completely sound and well rationalized. You support all of your arguments with extensive explanation based on the facts presented.
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Originally Posted By: sayjac
Originally Posted By: Garak
Originally Posted By: sayjac
To the topic, when someone can prove to me that flow is a significant factor in standard passenger car use, I might give it some consideration. Until then I'll take filtration first.

I would agree with that. I've never really bought into the argument that any off the shelf filter when used in its specified application is restrictive. That's never been an issue for me. But, to be clear, while I "prefer" a higher filtration efficiency, I don't think that any of the big names we see on the shelf or from OEMs aren't "good enough," either.

For example, I like the P1's 99.9% rating, let's say....

Completely agree. I'm not fanatical about it, I've used many a filter that didn't have a super published efficiency rating with no concern. But all other things being equal my preference would be toward the higher efficiency rated filter.

I guess the bigger point was, based on reading this board over the years filter flow is so insignificant in pc use, that it's not even worth mentioning imo.


I agree that filter flow is typically a non-issue. If the oil filter is designed properly, it will flow way more than an engine can put through it, even if it's a high efficiency filter like a PureOne. An oil filter is typically 15 times more free flowing than the engine's oiling circuit. Keep in mind that the flow forced through the filter & engine is coming from a positive displacement oil pump with a pressure relief valve.

The Superbusa thread shows that a medium sized PureOne only produced ~5 PSID across the media with 12 GPM of oil flow. The filter used in this test was a PL14006, which isn't a huge filter - it has ~100 sq-in of media, with is about the same as the PL14610 commonly used on 4 and 6 cylinder engines.

PureOne Flow vs PSID

The only time the flow performance of an oil filter may make a slight difference is when the oil pump is in pressure relief - which is hard to make happen on a normal passenger car (PC) unless your are revving the engine very high with cold oil. Once the oil is near full operating temperature (200 deg F), even running the engine at red line will typically not get the pump in to pressure relief - unless someone put some super high volume oil pump on a racing engine.

One thing that a very restrictive oil filter could do is put the oil pump into pressure relief much sooner/easier than a more free flowing filter. If the oil pump goes into pressure relief much sooner than it should, then there will be a reduction in oil flow to the engine compared to if the oil pump went in to pressure relief much later in the RPM range.

I've used 4 or 5 different brand/model oil filters on my Z06 and I've recorded oil pressure as a function of oil temperate and engine RPM (including near red line). I have seen no real difference in that data using all those different oil filters. Also, I have never seen any oil pressure reduction at red line, which means the oil pump never hit's pressure relief at red line when the oil is 200 F or above.
 
Originally Posted By: sayjac
I guess the bigger point was, based on reading this board over the years filter flow is so insignificant in pc use, that it's not even worth mentioning imo.

Absolutely. Efficiency can be increased, and while that doesn't matter a hill of beans to most, it certainly can to others, particularly if one is trying to stretch OCIs and use bypass filtration - efficiency is the whole point.

With respect to flow, aside from racing applications, we never see filters as a significant impedance to flow.
 
Originally Posted By: FetchFar
Originally Posted By: Cooper

I will say that I have settled on Wix filters at the moment. They are a happy medium and made really well! I just purchased 6 Wix 57055 and 6 57356 filters.


Medium nothing, those are premium filters, glass fiber plus cellulose blends. You chose well. Might as well use good ones, no reason not to.


The happy medium was that that they are not restrictive and they provide good filtration as well. They appear to be one of the best constructed filters in the retail market.

I will say, this has been one of the best conversations I have been a part of. Thanks to everyone who has contributed.
 
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