Originally Posted By: edhackett
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1. The Fujita paper where this notion came from, referenced in the SAE paper, was a bench test performed on non fully formulated oils ...
The study clearly states that a GF-3 "factory fill", a GF-4 "factory fill" and a prototype GF-5 were used. Sir, factory fill fluids are NOT "non fully formulated", as you claim. They are produced for consumption by the end user and are, in fact, in a state of full add-pack as delivered for use. Additionally, when the study was written, the "prototype" GF-5 has since become the fully-formulated product that is now their offering. It was only a prototype then as they were not yet offering GF-5 yet. But what was "prototype" then is in the bottle now, so ALL THREE LUBES were essentially as one can purchase then and now, and are in fact "fully formulated".
Originally Posted By: edhackett
2. There is no evidence that any "stripping" occurs under the normal process of changing oil. I am unaware of any studies that have looked at this. That usually means that it isn't an issue that needs examining.
I would agree that the word "stripping" needs perhaps to be defined here, so that we all don't get our panties wadded into a bunch. "Stripping" (as I am going to define it) simply means the removal of some portion of the TCB due to interaction with the fresh detergents and disperants in fully-formulated oils. IN NO WAY am I saying that "all" the TCB is removed, but some portion of it is; quoting here:
"However, when a dispersant is added, the film is removed and the film thickness stabilizes at a lower value. The antagonistic behavior of dispersants is well-known ... The interaction of ZDDP with dispersants and detergents not only impacts film thickness but also affects the film composition."
CLEARLY they state more than once that the film is "removed" and thickness is changed. Now - whether you want to call it stripping, removal, Disney-like magic, I don't really care. But it is, IMO, incorrect for you to state that there is no evidence of "stripping" going on; this study, and others, clearly describe and define it. This study, and others, have measured the thickness of the TCB relative to the OCIs, and found that the thickness varies with the OCI. The TCB will stabilize in thickness, and some of that is dependent upon temps experienced. If you object to the word "stripping", then insert your own word that would be found in a thesaurus that would reasbonably describe the effect of a film thickness being reduced and then rebuilt. Semantics ....
Originally Posted By: edhackett
3. Nobody knows because nobody has done a study under actual engine operating conditions.
I would agree; there's no data I know of that deals with the TCB and seals.
Originally Posted By: edhackett
4. The chemistry of the tribofilm is constantly changing throughout an OCI. The old film is altered by the new oil and evolves through the OCI as the ZZDP and other antiwear additives react to protect the metal. The daughter products of these are capable of forming a new film faster than the original compounds up to the point where they are broken down into components that can no longer form an effective film.
I do agree that the TCB is changing; the various studies detail this effect. Regarding the film, I cannot say with assurance when the film is fully formed, but what I can do is shed light onto the EFFECT of the film, and it's timeline. Here, we can use my data. Generally, the TCB is well formed (perhaps not fully, but a significant layer is now present) at 3k miles. I say this because the data clearly shows that at 3k miles, wear rates start to drop and they drop precipitously. It's hard to ignore 15k UOAs; data don't lie.
And this is what the study has to say:
"The wear rate dropped significantly with the 3000 mile drain oil, in fact the wear rate became practically zero."
Apparently around 3k miles is when the TCB effectiveness is quite apparent. The wear rate effect (and the implication of stripping and rebuilding) is not a light-switch; it does not simply go on/off with pure clarity in one mile or one hour. It is an devolving and evolving thing. What is clear from the study and my data is that at 3000 miles of typical exposure, the wear rates drop a lot. Whether it's Elf magic or the TCB or (insert X-factor here), the EFFECT is clearly seen around 3k miles of exposure. How that relates into hours of operation would be dependent on data I don't have.
Originally Posted By: edhackett
They stoped the experiment at 12K miles as several of the oils had reached TAN 3X TBN and had oxidized two grades thicker.
Close; they ran them to 15k miles; maybe that was a typo on your part?
And yes, the vis thickened and acid flipped. So what? The study says this:
"The viscosity of drain oils increased progressively as the drain interval increased from 3000 mile to 15000 miles, but the wear rates of tappet shims and friction torque did not change appreciably indicating the reduction in ware rate and friction is related to changes in oil chemistry with aging."
And this:
"It is interesting to note that the viscosity of the 7500 drain oil is about 20% higher (at 100C) than that of the 3000 mile drain oil and therefore, might be expected to show a lower wear rate because of increased oil film and the resulting reduction in asperity contact. But both oils showed similar wear rates indicating that the wear rate is controlled more by eh chemistry of the surface film formed at the contact than asperity contacts."
Again, my data echos this conclusion. I see that, in general, any particular engine family/series will exhibit a reasonable consistency in wear trends in macro-data analysis. But, these wear trends don't follow the vis chosen, or the ending vis in a UOA. Hence, it is very reasonable to believe that viscosity has very little impact on wear, as long as a reasonable grade is used (something that would be appropriate for general use) and is not allowed to turn to tar (gross neglect of lube state). Further, I've seen countless examples of TAN usurping TBN, often to 2x or more, and yet the wear rates are not affected whatsoever.
Originally Posted By: edhackett
The study was not designed to show new oil causes more wear ...
I agree the study purpose was not to show that new oil causes more wear. But, the study was designed to show how wear and friction change with the aging of the oil. It's a fine line between where you and I stand on this. I agree with you that they were not out to cause a panic that new oils are harmful; that is agreeable to me. But they certainly were out to prove that as oil matures (more specifically how the TCB matures), wear and friction are affected. Because one needs a starting point, and that point is logically an OCI, then "new" (fresh) oil is certainly within the realm of consideration.
Study states this:
"It is clearly seen that the fresh oil exhibits a much higher wear rate than the vehicle drain sample, but its absolute value is still quote low and quite acceptable."
I cannot agree more. NEVER did the study, or I, claim that new oil is a danger to equipment. While the data from both the study and my macro-analysis show that wear is much higher at the onset of an OCI, it is NOT, I repeat, IN NO WAY, SHAPE OR FORM, is it a cause for concern. New oil is NOT harmful, nor is the TCB effect it induces at the onset of the OCI. To put this in perspective, we have to understand that different is not the same thing as bad or wrong. The TCB is greatly altered at the OCI, and that changes the wear rates to large degree, but that wear is still VERY low. It's just that AFTER the TCB is fully mature, the wear goes almost to zero in in the study. And my data correlates to this effect. Macro wear data is never shown to be dangerous at the OCI; it's just elevated contrasted to more mature lubes. And perhaps this is why this entire thread is a boon into the oblivion. There is no claim by me, or the studies, that one should not change oil, nor that some "partial" OCI (replacing some portion of the sump but not all) is preferable. This is not the place to jump to any conclusions that are not directly supported by evidence. OCIs are not harmful. But, what is also clear is that overly frequent OCIs are not "helpful" (they don't reduce wear). Many folks will OCI frequently because of blind faith and a false sense of the old adage "If something is good, then more most certainly must always be better". Oil changes are good. But more are not "better". The SAE study, and my data, both prove that moderate OCI extenseions are both safe and desirable, AND can have the benefit of saving money. The alternative (frequent OCIs) pay no dividend in wear reduction, and waste service-able fluids (waste $$$).
This is why I am perceived by many as to be a "bully" (among other things I've been called), when discussing folks UOAs. Too many people toss out perfectly good fluid far too soon. And they do this because they think (they are programmed?) that new oil is "better". But the data of the study, and a VERY LARGE cross section of all manner of engines in my macro-data, all indicate that extending the OCI is actually beneficial. All I try to do is educate folks to this effect. And at times, I think some folks who do not respond to a gentle comment, eventually need a 2x4 upside the noggin. They pay for UOA data, and then promptly ignore it. They waste the lube AND they waste the data; both of which they pay for! If a person wants to change oil often, fine by me. But if they claim it's because they will get better wear, THEY ARE PATENTLY, INCONTROVERTIBLY, UNDENIABLY WRONG!!!!! They have the right to be wrong, but they do not have a right to go unchallenged. There is no rule on this website that states one can post a UOA with impunity, and demand that only people who agree with their wasteful practice be allowed to comment.. You want to waste oil and show the world? Fine by me. But don't get upset when I call you out of facts so terribly clear that only an imbecile cannot reason it through. FREQUENT OCIs DO NOT REDUCE WEAR RATES. EXTENDING OCIs REDUCES WEAR RATES.
Originally Posted By: edhackett
... the new oil was always run on new parts. They had not undergone the break in that valve train parts undergo. The used oil was always run on broken in parts.
No sir, that is not correct. Quoting the study:
"A different cam lobe and a tappet shim were used for each oil." Now, the study does not specifically state if the cam and tappets were new or broken-in, but it does CLEARLY state that each lube had a different part-group introduced. To me, the inference I take is that rather than stacking the wear induced from all tests onto the same single cam/tappet, they used a "new" (not brand new, but unique in that each had not been previously utilized in testing) set of parts for each oil. Each time they swapped oils, they set it up with a different lobe/tappet. Whether or not these were "new" (versus broken-in) or not, the variability you infer is not present. Each lube got a unique (and presumably reasonable equal) lobe/tappet set up.
Originally Posted By: edhackett
The second main uncontrolled variable is that since this was a bench test the new oil was never mixed with the used oil that carries over in an OC or exposed to new combustion byproducts. It remained "virgin" throughout the test, unlike what happens in the day to day operation of an engine.
I don't disagree here, but I do question your point? New oil is new oil. As soon as it would be mixed with carry-over (redisual) oil, then it's no longer "new". Each engine (and each person whom maintaines that engine) is going to exhibit a different level of how much residual is left to be mixed into the new oil. That is inescapable. However, residual oil is a bit of an overblown thing. It's unavoidable, and generally harmless.
Originally Posted By: edhackett
I've covered why UOA data can't be used to determine wear several times. If someone would like me to post it in this thread, ask.
I would agree that UOAs have their limits. But so does most any tool. UOAs are just that; they are a tool. One of many. What other tools do we have to determine wear? We could do tear-down analysis, measuring all manner of surfaces with a profilometer, and use gages to determine various clearances. But, that has two risks as well. First is that tear-downs are prohibitively expensive in both time and money. Also, (and this is less known), anytime you tear-down an engine, and then reassemble it, you do change some values in the measurables. If time & money were no object, and we could tear-down an engine every 5k miles during an OCI, then we'd be inducing other variables into the equation such as torques, alignment of surfaces and bearings, micro-scraches, etc. Tear-downs may be accurate to some degree, but they are not without risks and also are not really any more repeatable than other "tools" in the tool box. UOAs, do have limits; they cannot see large particles. We all know that. But then again, most wear is not made up of large particles; most of it comes from soot that is small and silica that enters via ingestion. PC (particle count analysis) helps understand the size of stuff, but it gives NO understanding as to context of material make up. Soot, Fe, Si, Al and all stuff is not qualify-able in a PC. (edit note: the PC can let us know size and quantity of particles, but not the quality/material of particles). So a PC is a tool, but it also cannot help us understand wear fully (if much at all). So, UOAs are not infallible, but they are a low-cost, reasonable view into "normal" equipment operation. If UOAs were a total farce, then we should never post one here ever again, and we should demand that the entire UOA industry cease and desist. Is that pragmatic? Nope. UOAs have a use, and as long as you understand both the benefits and limitations, you're better off than not having the information. UOAs cannot see large particles, by design of the technology. UOAs cannot see some chemical additives that are not reactive to the plasma stream. UOAs can at times confuse things based upon shape/form of the particle. But UOAs are REASONABLY accurate, and (by far) the cheapest tool we have that is easily utilized. They are not perfect, but they are most certainly useful if you understand how they work, and their limitations. They will not show all wear; they will show most "normal" wear.
I believe a lot of people misinterpret my UOA article. It was NEVER meant to induce a panic; there is no evidence to show OCIs being detrimental on a magnitude that will harm the engine. SAE 2007-01-4133 does not prove nor state this. My macro-data does not prove nor do I claim this. Rather, my study was an effort to prove that overly frequent OCI pay no dividend. Changing oil at 3k miles (as the industry has taught us that 3 months/3k miles is "best") does not provide any benefit in terms of reduced wear. None whatsoever. To the contrary, less wear is experienced as the OCI matures past 3k miles; the longer the better. (Note a limit of 15k miles, where both the SAE study and my data stop.)
