All you scientists out there need to try and answer this important contradiction. An appropriate answer here would unlock many important truths about engine wear and UOAs.
Buster just made an excellent post referencing this article: (http://www.practicingoilanalysis.com/article_detail.asp?articleid=401&relatedbookgroup=PowerGen
It says "For diesel and gasoline engines, there are a surprising number of laboratory and field studies that report the need to control particles below ten microns. One such study by GM concluded that, “controlling particles in the 3 to 10 micron range had the greatest impact on wear rates and that engine wear rates correlated directly to the dust concentration levels in the sump.”
Also "Much has been published about the risks associated with overextended oil drains and the buildup of carbon insolubles from combustion blow-by."
Now part of being a scientist/engineer is being able to mathematically visualize verbal formation and observations. If you buy the above quotes and the Jim Fitch article, then something should be obvious to those with a mathematics-science-engineering background.
If particulate debris causes most engine wear and we assume there is only a small amount of debris there after a fresh OC, then it should be obvious that the amount of engine wear should rise exponentially as the OCI progresses. Mathematically, this is a chain reaction scenario gentlemen!!!! Yes dudes, just like a nuclear fission reaction. In other words, at 5,000 miles, your amount of sump debris should be way way higher than it was at 1000 miles and if the debris causes the wear, then you should have way more wear from 5k to 6k miles than you would from 1k to 2k miles. In fact, if most wear truly comes from debris and there is almost no debris after a fresh oil change, then mathematically, there could easily be 50 to 200 times more wear going on between the 5-6k interval as there is during the 1-2k interval.
Now let's consider the myriad UOA's that this board seems to be obsessed with. They show no tendency whatsoever towards this kind of behavior. In fact, they may even show/suggest the opposite.....that wear may be lower from 5k to 6k than from 2k to 3k.
Now if somebody would like to come on here and explain this contradiction.............I believe many of us would be all ears. But don't anybody dare come on this board and be as illogical as to say that Jim Fitch's article and the UOA's jive.............that is nonsense.......there could not be a steeper or more extreme mathematical contradiction. I want some answers and maybe even some admissions!!!! Where are the scientists now? Where are the UOA experts........we deserve answers.
What's up dudes? Is Jim Fitch smoking the peace pipe or are UOA's ridiculously poor at quantifying engine wear? Does this statement from the article seem to suggest the latter is true as wear debris could end up still in the engine or the filter "hard particle contamination can agglomerate with soot and sludge to form adherent deposits between valves and guides". You be the judge!!!!
I'm out.........
1911.........The brainchild of John Moses Browning
UOA's versus Jim Fitch, et al!
- Thread starter 1911
- Start date
- Status
Interesting article. Been a Jim Fitch believer for a long time. Makes bypass filters more interesting. Can anybody give us fuel economy figures with and without a bypass filter?
Applying theory to the real world would mean that cars in Europe should break down before cars in the United States since European go for extended drain intervals. Is this really the case? I don't think so.
SSdude: You are exactly right!!
Labman: If true, in addition to better filtration, you would want to go to very very short OCI's because the article discusses damage from particles smaller than what any filter can deal with!!!!
The way the information was presented, simply keeping particles in suspension is not necessarily a benefit as these particles cause most of the wear. Just keep thinking about the mathmatics of a chain reaction as in nuclear fusion. At first there a few neutrons hanging around and some percentage of them fissure atoms releasing more neutrons. The rate of reaction and damage increases exponentially with time as more and more neutrons are working. A lot more damage is done in the 3rd or 4th billisecond than in the 1st one. (In reality, such a reaction would slow when the fuel expenditure gets to a certain point and there are not enough atoms left to fissure). However, our engines never get shy of metal to grind away.
I appreciate your opinions and observations, maybe the UOA's tell the truth on wear and if so, Fitch knows nothing about mathematics. But remeber, there is a quote from GM too!!! Are the UOA lovers smoking dope?????? Let's get some answers.
1911
To be realistic most cars will be junked before a well maintained engine will wear out. Gas engines really don't put as much garbage in the oil as diesel engines do. Or how many cars see a million miles? Compared to over the road trucks? The 1911 is almost 100 years old and more and more manfacturers are making their version of the pistol.
1911 - I appreciate your opinions and observations, maybe the UOA's tell the truth on wear and if so, Fitch knows nothing about mathematics. But remeber, there is a quote from GM too!!! Are the UOA lovers smoking dope?????? Let's get some answers.
I have seen no correlation between actual engine wear and the wear particles reported in UOAs. As far as i am concerned, looking at engine wear in a UOA is oil-astrology. ![[I dont know]](/forums/graemlins/dunno.gif)
It's easy to draw simple conclusions if you don't understand the systems or the variables. Oil analysis is as much of an art as it is science and those who think it is a science will have a lot of surprises (and disappointments). It is far from black and white.
Traditional UOA does not measure "particles" in engine oils so most of the data doesn't tell you what's really there. To see what I mean go look at the pictures on the reports posted under transmissions in the oil analysis section. In many cases you will see there is little or no correlation between wear elements levels with the particle counts or the photomicrographs. The particles bigger than 3-5 microns are invisible to the ICP instrument commonly used to measure wear elements.
Particle size does play a role in wear and fewer particles results in less wear (in most systems), but it depends on the wear mechanism. Small particles are not as detrimental to engines as they are to high pressure hydraulics or compartments with ball/roller bearing and gears, where elastohydrodynamic conditions exist and things are "harder". Engine bearings for example are designed to "absorb" a few wear particles without damage.
In filtered systems using the proper oils you will not see an exponential growth of wear particles because the wear rate is not that great. Exponential doesn't necessarily mean fast. The filter and oil change intervals limit the amount of particles and additives do control the formation of oxidation products. Even crappy filters remove lots of particles.
One last thing, not all particles cause wear and I'm not a "dude"!
quote:You may not be a Dude but you surealy are stinky!!! Seriously, if you are right (and I believe you are), then the vast majority of members on this board are grossly misusing and over-interpreting the data they get from basic UOA's. They commonly use these to refine oil choices based on alledged concentrations of wear particles. If you are right, then they need a reality check and I hope you just delivered it. Have you explained this before here? You are also perfectly correct in that exponential growth does not mean fast (at infinite times it would of course)if you generate very little initial debris to kick off the process at a slow rate. However, I think you see what I meant in terms of the UOAs Stinky. IF the UOA's were literally clearly describing all the wear debris, then you would clearly see a change bigger change in the counts going from 6k to 7 k miles versus 1k to 2k miles. In other words if the PPM typically went up by 8 points between 1 and 2k, then it should go up a lot (maybe 70 to 100 points) more between 6k and 7k (based on the joint asssumptions that debris causes most wear and the UOA are actually quantifying it). The latter is probably not true (as you say) and even if the prior is true, the wear rates may still be low enough that it all doesn't really matter too too much. Regardless, for the picky amongst us, it is still an argument for limiting OCIs to less than this new Mobil 1 15k stuff.
Originally posted by Stinky Peterson: It's easy to draw simple conclusions if you don't understand the systems or the variables. Oil analysis is as much of an art as it is science and those who think it is a science will have a lot of surprises (and disappointments). It is far from black and white. Traditional UOA does not measure "particles" in engine oils so most of the data doesn't tell you what's really there. To see what I mean go look at the pictures on the reports posted under transmissions in the oil analysis section. In many cases you will see there is little or no correlation between wear elements levels with the particle counts or the photomicrographs. The particles bigger than 3-5 microns are invisible to the ICP instrument commonly used to measure wear elements. Particle size does play a role in wear and fewer particles results in less wear (in most systems), but it depends on the wear mechanism. Small particles are not as detrimental to engines as they are to high pressure hydraulics or compartments with ball/roller bearing and gears, where elastohydrodynamic conditions exist and things are "harder". Engine bearings for example are designed to "absorb" a few wear particles without damage. In filtered systems using the proper oils you will not see an exponential growth of wear particles because the wear rate is not that great. Exponential doesn't necessarily mean fast. The filter and oil change intervals limit the amount of particles and additives do control the formation of oxidation products. Even crappy filters remove lots of particles. One last thing, not all particles cause wear and I'm not a "dude"!
quote:1911, that's like the old saying, "If the only tool you have is a hammer, everything looks like a nail." Much of oil analysis interpretation I see here sounds like fortune tellers reading tea leaves. I think oil analysis can be a valuable tool, but it's only one tool. Much too much is read into the results.
Originally posted by 1911: . Seriously, if you are right (and I believe you are), then the vast majority of members on this board are grossly misusing and over-interpreting the data they get from basic UOA's. They commonly use these to refine oil choices based on alledged concentrations of wear particles. If you are right, then they need a reality check and I hope you just delivered it. Have you explained this before here?
I think the answer to your questions are obvious, 1911. If your theory that wear should increase exponentially as miles accumulate were true, and if UOAs (without undue Si contamination) show that the relationship is not exponential. And if actual, real-life engine wear follows UOA results infinitely more closely than the your exponential-wear theory--and they do--then UOAs trump speculative theories (or at least your understanding of them).
Thanks for helping me make my point again.
[ April 10, 2005, 02:00 AM: Message edited by: Jay ]
[/qb][/QUOTE]1911, that's like the old saying, "If the only tool you have is a hammer, everything looks like a nail."
Much of oil analysis interpretation I see here sounds like fortune tellers reading tea leaves.
I think oil analysis can be a valuable tool, but it's only one tool. Much too much is read into the results. [/QB][/QUOTE]
Thanks, well said. I believe you couldn't be more right. I also really appreciate those in the business stepping up to the plate and discussing the real limitations of this technique. However, there are many in the business who would rather these things not be discussed because it could potentially lower the amount of business they get. Others simply do not know or understand what Stinky just laid out.
1911
Hi,
I have been using MANN-HUMMEL centrifuge by-pass filters on my diesels for some several years. The reason is to minimise soot build up and they have been very successful indeed
I believe by-pass filters that do not "rob" too much flow offer some advantages. We are convinced that these are far superior in many ways to the previous Raycor and other cartridge type devices
The centrifuge units do filter out to below 1 micron but we still used UOAs to determin the optimum oil change point
We are now using cleanable SS 30micron full flow filters as the centrifuge has virtually rendered the normal FF filters a waste of money
We could not and would not try to measure a fuel economy gain/loss due to the range of variables involved
Our average uptake of contaminants has been 0.0025gr/km giving a cleaning point at about 230k kms
I do not believe that UOAs provide a reliable measurement of engine wear rates. Trended they are but a guide amongst others to engine condition
Regards
Doug
I have some reservations about the conclusions made based on UOA's. The type of oil analysis we do isn't designed to evaluate oils, it is for detecting abnormal wear, contaminants, maintenance shortcomings, improper operation, and helping to optimize change intervals. Luckily there is room for error so many of the choices have little affect on the overall life of an engine. I think it has been shown that fewer contaminants result in less wear but so what? that's the question we have to ask - SO WHAT? Is it even measurable? How does it contribute to the big picture? I don't think a decrease or several PPMs from one oil change to the next indicates a significant change but technically it does indicate lower wear levels so it is reasonable to assume that if one oil results in lower wear levels then it will result in longer life.
In some cases people may be trying to attach significance where there is none but who am I to criticize them for doing this or to point out that they wrong? Just because a person can win an argument doesn't mean they should. Besides that there are lots of folks here that have fun experimenting with oils and filters and I have fun participating.
1911 you are right about about some not wanting to discuss the limitations of the service they offer. My experience is that if you want to solve problems you have to know the limitations of your measurement methods and procedures. My training is in science and before that I was a mechanic for 15 years. At no time in my career have I had any training in law or marketing so I don't always know when to keep my mouth shut. ![[Wink]](images/icons/wink.gif)
[ April 10, 2005, 02:37 AM: Message edited by: Stinky Peterson ]
[ April 10, 2005, 02:37 AM: Message edited by: Stinky Peterson ]quote:Jay......I don't have an exponential wear theory. It should be obvious mathematically that if Fitch's statements are correct,(and I never said they were) then the wear rate would have to go up exponentially. In a logic class Jay, it would sound like this......... A) If particles cause wear, then the more of them there are, the higher your wear rate should be. B) There should be more wear particles at higher operating times than lower operating times. If A and B then C: Therefore, more wear would occur at higher hour intervals than similar length intervals at lower time when the oil was cleaner. This is due to increases amounts of wear causal agents being present. Interest in the bank is a similar function too Jay. Interest leads to more capital which leads to increasing interest. These are cases mathematically where an action (interest, wear, nuclear fission) leads to an increased amount of the action. These are exponential functions bro. This example may help. Do you know how nuclear fission works? Basically Jay, a neutron splits a uranium atom which releases more neutrons. The rate of the reaction occurs increases exponentially with time because the initial action helps to allow/create increasing amounts of the action. If wear particles create more wear, then their amount will continue to increase at an increasing rate as there are more of them to help make more of them. Jay, this probably does go on and is actually one of the reasons you change your oil. Mathematically speaking, the exponent will depend on the probability of newly released neutrons to fissure more atoms. At the bank, it depends on the interest rate, and with our wear scenario here, it depends on the probability of fresh wear particles to do damage creating more wear particles and as Stinky pointed out, some of them do not. Now if the amount of wear is low adn many of the particles are not likekly to do damage, then all of this may go unseen as Stinky alludeed to. You would need a technique that's more sensitive than what we use to see it or it would not show up until very high OCI's beyond what a sensible folk would ever run. (exponential growth is always very significant given long enough times, look at 5% interest over 1000 years at the bank.) Now Jay, is this all really some crazy rocket science theory (hypothesis, guess, etc) or plain common sense? You're scaring me Jay. You give me way to much credit by referring to 9th grade math as "my theory". Now did you read what Stinky wrote? My comments were based on basic and indisputable math (basically, an if A then B scenario), yours are based on the assumption that your UOA really accounts for all the wear (and corrosion) metals released in the engine. Take your beef up with Stinky, you're too math illiterate to see that you don't even actually have a disagreement with me here.
Originally posted by Jay: I think the answer to your questions are obvious, 1911. If your theory that wear should increase exponentially as miles accumulate were true, and if UOAs (without undue Si contamination) show that the relationship is not exponential. And if actual, real-life engine wear follows UOA results infinitely more closely than the your exponential-wear theory--and they do--then UOAs trump speculative theories (or at least your understanding of them). Thanks for helping me make my point again.
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=1;t=008994#000013
Maybe it gets cleaner with use.
Yes, Jim is smoking the peace pipe ....
There is an optimum drain interval that yields the lowest wear rates. It's NOT a 3000 mile interval since wear rates actually rise significantly right after an oil change. (I have my own theories about why this is). It's also not a drain interval that overextends the oil on a consistent basis. However, that optimum interval varies widely, depending on both the quality of the base stock and additive chemistry, as well the amount of synergism between the two.
Based on my 27 years of experience with synthetic lubes and extended drains, as well looking at the oil analyses on this site, I'd say the optimum change interval with conventional oils is perhaps 4000-6000 miles. The optimum change interval with average quality, OTS synthetics (including Group III's) is perhaps 8000-12,000 miles. The optimum change interval with the best, ACEA, "A3/B4" or "A5/B5" quality, PAO/Ester synthetics is more like 12,000-18,000 miles.
My experience has been that non-turbocharged, four cylinder engines (w/ modest power levels) will safely allow the longest service intervals. Large displacement V-8's with relatively small 5-7 qt sumps, and turbocharged 4/6 cylinder engines will require the shortest change intervals. The current V-6 and straight six engines are somewhere in the middle in terms of change intervals.
Ted
quote:These are all great points. Mark gave some excellent information on this topic.
Seriously, if you are right (and I believe you are), then the vast majority of members on this board are grossly misusing and over-interpreting the data they get from basic UOA's.
![[Cheers!]](/forums/graemlins/cheers.gif)
quote:Thanks Ugly3, You may be right or it may be possible that as Stinky alluded to, that the differences may actually be there but are too insignificant to see and too insignificant to cause your engine to need replacement noticibly earlier than normal. It may even be true that (and I'm not saying this happens but just for theory here)if you had 5 times the wear rate from running really long intervals that you'd may still get hundreds of thousands of miles out of the motor and not notice much on UOA's. It also may be possible that the damaging effects of these small particles are overrated. The point of my post was to simply state the obvious mathematical implications of the Fitch paper. I'll post more on this in a minute since it's clear that at least one person here cannot understand very basic mathematical concepts.
Originally posted by Ugly3: There are way too many engines running 10,000+ mile OCIs and lasting 100,000 of thousands of miles for the long OCI more wear theory to be accurate.
Hey...
How thick is the average hydrodynamic film?
Wouldn't it be thicker than most of these miniscule wear partciles Fitch describes?
And if the film is thicker, these wear particle would have a hard time getting any kind of "bite"--no?
I think Stinky's points are brilliant--basically that the UOA is simply the most convienient tool to spot a trend--nothing more, but certainly nothing less. UOA's will continue to be of great value to many--read on...
We currently take an oil analysis of every drain on the ten heavy trucks I manage. I was able to spot four Caterpillar engines beginning to self destruct due to incompatibility with a particular transmission (crank thrust bearings were wearing way too thin causing crank end-play to be as high as 250 thousandths (yep, 1/4") ![[Eek!]](images/icons/shocked.gif)
The UOA's showed that this was happening well before a piston came through the side of a C13 block... Cat made it right (new engine) ![[Smile]](images/icons/smile.gif)
, and has corrected the problem with an updated thrust washer design--but the UOA's we took along the way gave us plenty of evidence that the engine was essentially coming apart from the inside. I delivered the broken down truck to the Cat dealer (on a hook, natch), and handed the service manager four pages of UOA's showing the trend; this allowed me to assert that it wasn't abuse of the engine which caused the failure, and no questions were asked.
Dan
The UOA's showed that this was happening well before a piston came through the side of a C13 block... Cat made it right (new engine) , and has corrected the problem with an updated thrust washer design--but the UOA's we took along the way gave us plenty of evidence that the engine was essentially coming apart from the inside. I delivered the broken down truck to the Cat dealer (on a hook, natch), and handed the service manager four pages of UOA's showing the trend; this allowed me to assert that it wasn't abuse of the engine which caused the failure, and no questions were asked.
Dan- Status
