Originally Posted By: dnewton3
Quote:
Thank you for not taking offense; I absolutely assure you that none was or is intended. After reading several of your previous posts, I doubt that any information I post can change your mind; you seem to me to be firmly entrenched; but I love surprises.
I am beginning to appreciate the honest manner in which you jest; I can take a joke, and look forward to the exchange! In that manner, I think it is you who may be surprised at what these studies do and do not prove! Please read on, but be forewarned, my answers are lengthy and wordy. I have been accused many times of having diarrhea of the keyboard; can't imagine where that comes from ...
I, too, have a quality control background; I do statistical process quality control for a living now in the HVAC manufacturing industry. Your experiences and mine are probably similar in terms of understanding data sourcing and analysis I would think.
Additionally, I have previously stated, and will do so again, that I don't think BP filters are worthless. To the contrary, they have a very pragmatic application as a fiscal savings tool. Additionally, in environments that require a hyper-clean fluids, they are paramount to successful operation. However, that does NOT extend to the common use in how they are viewed on this site, as well as the hap-hazard manner in which folks interpret the limited studies that have been done on them. I hereby again state that I am constraining my comments to the automotive applications, and typical use we see here. I'm not speaking to other industrialized applications; that was not my point here. So please do not bring things into the conversation that I neither stated or implied.
If you don't own the SAE papers, then you're grossly misinformed and/or ignorant (not intended as a slam but a description of the lack of info) as to the content of any of them. I do have a copy of two of them, and I'll go ahead an purchase one more. I'm going to exclude the one from 1966; it's nearly 50 years old and cannot hope to offer any relevance.
Before you dismiss my position, I think you should understand how it is that I have come to eschew the two studies I do own copies of. Rather than type it out, I'll quote myself from another post ...
this first quote are my statements regarding the GM filter study 88-1825:
Originally Posted By: dnewton3
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:
https://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 used oil 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 used oil analysis 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.
Now, I'll address the Cummins BP filter study 71-0813:
In similar fasion, and to try and make things a bit more brief, my objections to the Cummins filter study are paralleled to the GM filter study in that there is no practical application for which they were developed. I'll enumerate in a brief sense and cite the direct info;
page 2 - 1st paragraph:
"Measurement of the abrasiveness of particles in the field of samples could not be made. ... differences [exist] in the abrasiveness of the field oil sample contaminants and the contaminants used in the laboratory test oil mixture. ... it is believed any differences would affect only the absolute wear values and not the relative wear with various filtration systems."
What this states is that they cannot find a manner to replicate the actual wear data, and they are implying a relative ratio of filtration in the lab. This is similar to the statement that GM made where they were able to differentiate the filtration effect ONLY because they grossly manipulated the inputs. In the actual field data analysis, they could not determine nor replicate the perceived disparity if filtration effect! In short, while they can show a disparity of performance in the lab, they cannot find a manner to correlate that differential to the actual field data in terms of actual wear. That is a HUGE admission that the lab data may not relate to real world use!
As to the topic of filtration efficiency chosen for the experiment, it's my opinion that they may have been reasonably representative of the times back then (1971) but the filters they chose do NOT represent what is typically available today in terms of full-flow performance. On page 2, paragraph 5, they disucss using a full-flow filter they call "60um" (yes, that's sixty), which has a rating of max efficiency at 95% at 40 um. They do not state it's absolute at 60um, but they do show a reasonable efficiency (95%) at 40um. Now, that is NOT a filter which any of us would have to buy today off the shelf. I can EASILY go find a filter for $6 that is 99% at 20um at any Walmart. This is important because it grossly taints the view of what "normal" wear is associated with. Their baseline filter is not in any way what I consider to be "normal" in terms of off-the-shelf performance for typical automotive applications today, or even in the last two decades.
Additionally, page 2, paragraph 6 talks about he BP filter they chose. It was rated at 3um, but there was no stated efficiency at that size. Also, it is a depth media
750 cu-in system. That is HUGE in terms of total capacity, and has extreme effects that most any filter we'd see on a car cannot replicate. Any typical Amsoil, Frantz, Gulf Coast, FS2500, etc we'd see on a Honda or a F-150 or a Duramax will NEVER be anywhere that large. The basis of their BP element has no practical application; you'd never see anything that enormous on a typical consumer-driven vehicle. Why my objection here? Because they ran the testing to a manner which fully loaded the full flow filter to a dP media differential of 25 PSI! The huge system they used had a FF filter that had no BP relief valve, and so when they paired that heavily loaded FF filter with a giant BP element, they benefited from an overly BP-friendly flow ratio. Typically BP filters see only about 10:1 flow ratio; the FF runs 10 qrts for every 1 qrt through the BP. But by using a FF filer that is essentially plugged off, they allowed that giant 750 cu-in BP element to keep on performing which greatly shifts the flow in terms of what is really seen in a typical vehicle. The filters were NOT mounted on the engine; they were plumbed into a sump system that was separate from the engine and fed the same sump volume!
Just so you have a conceptual idea of how big the BP filter media was for this study, at 750 cu-in, it has 65% more volume than a Big-Block-Chevy engine! Yes - that's a LOT of filter media, isn't it? 750 cu-in is more than three gallons of volume! Where would you mount that BP filter on your Accord? In the trunk? I suppose, if you drove a Ram 1500 or Ford PowerStroke, you could mount that behemoth in the bed!
They run two types of tests; one is a wear-rate test and one a wear-out test. In both tests, they essentially have to grossly over-dose the sump to facilitate wear that can be quantified in the allowed duration of testing. Again, just like the GM study, they significantly slam the sump with fine AC dust to induce heavy wear. Page 5, in the wear-rate description they speak to the repeated hourly inducement of dust slurry, to a point where they could not longer measure a shift in wear. Essentially, they dump in the equivalent of 7k miles of contamination in just a few hours. In the wear-out testing, they run the engine until it can no longer hold oil pressure and/or consumed too much lube (an amount they did not define in the text). They then measured weight loss of critical components. Again, they ran 7k miles of simulated ingestion in just 5 hours; the equivilant of running 1420 mile an hour! That is approximately 23x greater than what would be "normal" at 60mph, and they did this at WOT full rated speed and full load. They never operated the engine in a "normal" sense of accelerating and coming to steady cruise state. This will admittedly accelerate the wear of ANY engine when run at WOT and full load! Do any of us run at WOT from the moment we start to the moment we run out of oil pressure?
Page 6, paragraph 2 they discuss the "Test Results" ...
Here they take a similar stance to the GM statement of applicability; "
These wear rates seem to be toward the high side based on field experience with the engine tested." They mention two reasons the lab experiement does not replicate real world wear:
1) acknowledgement of the WOT/full load system not being typical of real world use
2) acknowledgement that there was never any shutdown; shutdown would allow contamination to settle out and result is reduced wear at start-up, which field use engines benefit from
Page 10, last paragraph:
"
... this evaluation has shown the use of good full-flow fitlration, combined with bypass lubricating oil filtration, will result in extension of engien wear life up to two to three times the wear life obtainable with only good full-flow filtration."
Here's my beef with this statement; it does not replicate what is real-world to us today for a few very important reasons:
1) we don't have to worry about a 95% 40um filter being our baseline; we can get MUCH better filtration today for a pittance of cost
2) the BP filter they used was HUGE in terms of total capacity and efficiency, and they had to run wear-out tests for about 40 hours; no normal BP element we'd see on a car/truck for our use can reach such duration or efficiency
3) OCI duration was never a manipulated variable
In regard to the last point, this is my beef with all of you who point to these type studies as your "proof" of concept. There is no study that I'm aware of in the SAE journals (or elsewhere) that specifically uses the OCI duration as the manipulated variable; all these studies use the filtration efficiency as the variable. Therefore, you cannot point to the current set of filter studies as proof that they show any relevance in negating OCI duration; cannot be done! You cannot speak to what does not exist!
Generally, these two studies were grossly manipulated in terms of massively accelerated wear via heavy dosing of contamination that does NOT represent real-world conditions. They contrast the best advantages of BP filtration against a sump that is NOT afforded the variability of OCI manipulation.
We would all agree that what reduces wear is clean oil. It is my contention that two general concepts need to be understood:
a) for any piece of equipment, there will be a level of acceptable contamination that will sustain a desired lifespan
b) for any level of acceptable contamination, there is a means of either filtering or flushing out the contamination to maintain that desired effect
You see, most of you don't understand what you're implying by reading a simple, glorified synopsis in the SAE market place. You don't see what was and was not done in terms of making these studies consumable for ease of production.
I do stand by my statements regarding BP filtration:
- generally a complete waste of time/money for most folks as they will not manage the system via used oil analysis, PCs, visual observations,etc to a sensible end in terms of typical vehicle use
- there is NO PROOF that BP filter systems reduce wear tangibly to a degree that is UNIQUE and could not be reproduced via other means (OCI manipulation)
- BP systems are a fantastic tool to extend your OCIs but ONLY if you manage the overall program with a fiscal presence of mind
- BP systems are likely to "appear" to reduce wear, because no one realizes that they are holding the OCI duration as a constant, rather than the level of total wear as a constant; this is a paradigm shift that folks, even in industry, cannot seem to latch on to
- what I believe and profess is that for "normal" operation (sensible OCIs), BP systems will never reduce wear over the alternatives because of two things; 1) the soot levels will not accumlate to a level of being large enough to produce significant harm and 2) the normal silicate ingestion level during the OCI is not anywhere nearly as grotesque in terms of total volume that is generated in the lab testing
- I do agree that BP systems can hold contamination down to acceptable levels for longer OCIs, whereas the extension of an OCI that has only a FF filter will, at some point, reach a point of degradation that tips the scale to the favor of BP filtration. Each equipment application will be unique in this regard and would need experimentation to determine that tipping point
Please explain to me how you all believe these two studies replicate a reasonable sense of real-world application?
- the GM study dumped 570k miles of junk into the sump and NEVER changed oil, and used a baseline of a 40um filter for contrast; GM admitted their conclusions would never be seen in real world use because filtration disparity would not manifest to any such large differential
- the Cummins study also dumped huge amounts of silica into the sump, used a "60um" filter (absolute) as baseline for contrast, and then used a BP filter element (the size of Texas), while allowing the FF filter to essentially blind off; Cummins admitted the study wear data was only relative and not representative of real world numbers as well
HOW IN CREATION DO ANY OF YOU THINK THESE STUDIES PROVE BP FILTERS DO ANYTHING TANGIBLE IN THE REAL WORLD? I caution each of you to NEVER latch onto a synopsis of a study and claim it relevant until you READ the ENTIRE STUDY! I may be the last man standing in this regard, but I do NOT accept these two studies as having any applicability whatsoever to the concept of BP filtration in today's vehicles.
The key I'm tying to impress is that there is a lack of information regarding how OCIs effect wear contrasted to alternatives. There are studies that show finer filtration does reduce wear, but they are heavily biased via serious manipulation, so much so that they are not applicable to real-world conditions. Therefore, when I state that BP filters don't really reduce wear, I am contrasting that approach to one of a well-managed OCI program. NOWHERE that I know of has any study been done regarding comparing and contrasting these two different approaches. The studies you all claim to be relevant are not because:
a) they do not study alternative methodology
b) they do not represent applicability to actual field conditions
Now, ihatetochangeoil, I believe I have shown how those two studies are NOT what you want them to be; I have completely discredited them in terms of real-world applicability. I cite the specific quotation (pg and paragraph) and analyze how they do not relate to real-world use. If you believe I'm in error, then by all means purchase those two studies and counter my points with the same study data available to all. And, regarding the other four studies you cite, I will say we should negate the one from 1966; probably just too darn old. Pick one more and let's dissect it as well.
Be careful what you choose; it may well not represent what you think it does!
Thank you Dnewton.
You have a way of explaining things very simply and in a manner even I can understand.
You are an asset to this site and I thank you for your input
