I am sure those studies have been done, possibly going as far back as 45 years. But it would require literally days, if not weeks, to do a comprehensive literature search of all the professional automotive, engineering, and tribology journals that are relevant to this topic. If you are lucky early on in your search, you will find a review paper about oil analysis, with an extensive bibliography.
Why do you think UOA "wear"...
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I am sure those studies have been done, possibly going as far back as 45 years. But it would require literally days, if not weeks, to do a comprehensive literature search of all the professional automotive, engineering, and tribology journals that are relevant to this topic. If you are lucky early on in your search, you will find a review paper about oil analysis, with an extensive bibliography.
Yes, but if an oil tends to do well under all of these conditions I believe it safe to say that it stands out. PP has done this which is why I like it. From fuel diluted hybrids to 10k OCIs to using 20wt in a 30wt+ engine to a heavily moded race car, the results continue to impress. A broad test spectrum will tend to even out individual variables.
So I think UOAs can be very useful if there is a large enough data base, but a single one is only a data point. Isn't that what Terry had said all along?
If PP has done significantly better than another oil over several UOAs under the same conditions in the same engine, it might be concluded that PP stands out above the other oil in that engine.
What seems to typically happen here is a driver does a couple of UOAs each on one or two oils in their engine and conclude which is best, often with very little difference in the UOA results. Or, they compare their UOAs with other UOAs done by other drivers on other engines under different conditions and conclude that Oil A is better than Oil B, again with very little difference between the UOA results.
When I look at the data here, I see the vast majority of UOAs with low metals, regardless of engine and oil used. On those relatively few occasions where UOA metals are high, it’s usually due to engine break-in or a problem with the engine. I don’t recall any case where the consensus was that the metals were high because you used the wrong brand oil. (There might be a few exceptions where someone tried an oil quite different than that recommended by the manufacturer and had high metals in their UOA).
Therefore, if one considers all the BITOG UOA data on healthy, broken-in engines, one might conclude that it doesn’t matter what kind of oil is used; there are no oil standouts for the vast majority of engines using typical OCIs. Such a conclusion has just as much validity as the conclusion that Oil A is better than Oil B in my typical engine based on the UOA data at BITOG. This is because the UOAs here contain too many variables to achieve accurate conclusions.
However, given the size of the BITOG membership, we could probably get some reasonably valid data by running a more controlled test. If there were, say, 30+ members who had healthy broken-in engines of the same family and were willing to participate, there might be a chance at finding a preferred oil (if such exists) for that engine family. It would probably take at least 6 months, but it could be done.
In the case of 30 participants, simply take three oils, divide them equally among the members and have each one run at least one (much better to have at least 2) UOAs under controlled conditions. The controlled conditions would need to be things like a new air cleaner, same oil filter, a pre-flush run of the oil to be tested, and perhaps a few other things (like the OCI, and perhaps fuel grade and possibly brand). This would generate much more valid data than the essentially random data that is here now.
I was hoping to keep statistics off the consideration list so we could focus only on:
1. What happens to the wear particles inside the engine (that is, are there factors that affect their chance of making it into the oil sample). As I described earlier, I think there are and some of them are oil dependent.
2. Of those particles that do make it into the oil sample, due to ICP's inability to detect particles larger than 5,7,or 10 microns, how much underestimation of wear mass occurs? Of course ICP doesn't perfectly measure particle sizes of, say 5.0 microns, and make no measurement of 5.01 microns. There is a sensitivity curve as a funtion of particle size. So the measurement accuracy will depend on the particle size distribution of the wear particles, which may be oil dependent. We need good test data from a study on this to confirm or deny this. Without it, we must leave this as a another factor that makes the conclusion that, given a statistically significant data set from Oil A and Oil B, one giving an average of 10 PPM of wear metal X while the other gives 15, that the former prevents actual wear better than the latter, a false conclusion.
I'm writing this all weekend from a Blackberry which is really to write good hard to write to long sentences with. So forive my poor sentences above: hopefully they get some of my intent across but maybe not enough. I have omitted some important things I wanted to say, so more may come later.
1. What happens to the wear particles inside the engine (that is, are there factors that affect their chance of making it into the oil sample). As I described earlier, I think there are and some of them are oil dependent.
2. Of those particles that do make it into the oil sample, due to ICP's inability to detect particles larger than 5,7,or 10 microns, how much underestimation of wear mass occurs? Of course ICP doesn't perfectly measure particle sizes of, say 5.0 microns, and make no measurement of 5.01 microns. There is a sensitivity curve as a funtion of particle size. So the measurement accuracy will depend on the particle size distribution of the wear particles, which may be oil dependent. We need good test data from a study on this to confirm or deny this. Without it, we must leave this as a another factor that makes the conclusion that, given a statistically significant data set from Oil A and Oil B, one giving an average of 10 PPM of wear metal X while the other gives 15, that the former prevents actual wear better than the latter, a false conclusion.
I'm writing this all weekend from a Blackberry which is really to write good hard to write to long sentences with. So forive my poor sentences above: hopefully they get some of my intent across but maybe not enough. I have omitted some important things I wanted to say, so more may come later.
Here is a good article on the subject of this thread: http://nov1.m.yahoo.net/yng0/QU3dZ.B8lsj...oup=OilAnalysis
I don't quite know how you would digest an oil sample. I work for a mining lab and we digest thousands of crushed rock and soil samples every day by dumping nitric and hydrochloric acid on them, but I'm not sure how oil would react to that treatment. Oil and water don't mix (acids are generally used dissolved in water). It's probably possible, just maybe not as easy as you think.
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I'm sure it's possible ...and it may not be that complicated ..but it would surely disrupt the typical lab's "turn your head and cough" UOA process.
This is a long read ..and the graphs are long gone (the only ppm readings are those mentioned by other posters) but this guy used aerospace labs in his research. He was so naive about typical automotive oil testing that he rejected the one (4th or 5th lab) that he paid for out of pocket. The regular UOA was typically 84% lower in readings. DalessII's filter test
Now ..I'm ASSUMING that these were digested samples. It's the one method that would reduce all metals to readable levels. They would be reduced to the particle level. Now in the aerospace sector they may have other methods of determining TOTAL METALS and integrate them to a ppm equivalent.
In any event, his typical Fe reading was somewhere around 2400ppm where, over a 5k OCI ..one might expect 20-40 ppm on a bad day.
Interesting, Gary.
BTW, I just changed my oil and wiped off the ferrous debris onto a piece of clear plastic and paper towel (from a drain plug magnet and MagnaGuard magnet, respectively). I will analyze them with a microscope at work this week, as I've done before.
BTW, I just changed my oil and wiped off the ferrous debris onto a piece of clear plastic and paper towel (from a drain plug magnet and MagnaGuard magnet, respectively). I will analyze them with a microscope at work this week, as I've done before.
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Ah-HA! Well, it appears that it is indeed a rather laborious and complicated process over the procedures for aqueous digestion. Then again, this is EPA anal standard
ACID DIGESTION OF OILS FOR METALS
ANALYSIS BY ATOMIC ABSORPTION OR ICP SPECTROMETRY
http://www.epa.gov/epaoswer/hazwaste/test/pdfs/3031.pdf
ACID DIGESTION OF OILS FOR METALS
ANALYSIS BY ATOMIC ABSORPTION OR ICP SPECTROMETRY
http://www.epa.gov/epaoswer/hazwaste/test/pdfs/3031.pdf
Neato. I guess the acid is able to leach the metals out of the oil after all. Not really much more complicated than digesting a soil sample either. Should be able to find someone to do that for you... we have a few clients that give us their own methods and have us do them, but if you just want one sample done we'd probably tell you to bugger off.
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