If you are running Brand X for many years and it is making oil residue deposits in the engine, along with that oil residue is some wear metals that are embedded in those deposits. Now you switch to Redline, it frees up a lot of those deposits over the next few OCIs and so also the wear metals embedded in those deposits. Now your wear metals are way up with the Redline, but were caused by Brand X. Makes perfect sense to me. Could happen with a switch from any cheap conventional to a high detergency oil.
"Engine oil viscosity has VIRTUALLY NO EFFECT ON WEAR."
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Definitely an interesting idea. The only reason I have a hard time believing this idea with RL is because we don't see this happen with other high detergency oils such as Motul/Delvac 1 or Amsoil S3k. Definitely a possibility though. Another one is simply that RL doesn't react well with moisture.
Keep in mind that in the Paradise Garage study there was a 3000 mile "flush" with Amsoil oil before the Amsoil tests were started. This was done to minimize the "carrover" from the Mobil 1 run. So in theory, the Amsoil test start should have had a minimal influence from the prior oil.
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We've rehashed this a few times ..ad nausium ..but...
I think that everyone agrees ..regardless of origin ..that in the terms of wear metal particles ..less is always preferred to more.
Whether they have ulitmate practical impact on longevity is the only thing uncertain. Sure, I'll buy the "disturbing of established protective boundary layers" possibility ...I'll also buy the difference between particle suspension, retention, AND production.
There's a whole lot of data that doesn't just neatly fit into a box here. We see "switch hitters" have mixed results when going to something like RL ..yet we don't for some GC users (although on a side note ..virtually no one ever subjects any oil to any "endurance" runs and tend to form "projected" opinions based on limited short duration results.).
So we all can somewhat agree that UOA data is always going to be comparitive data and needs far too many data points to be "authoritative and comprehensive" to any but the most experienced (Terry and the like).
..but..no matter how you shake up the "what if's" and the "ya ..buts" ...is there anyone here who would continue to use an oil that produced MORE wear metals over another?
Take my situation. 10k M1 xw-30 78 ppm Fe compared to D1 for 10k @ 28 ppm (plug in any oil you want). Which oil am I gonna choose assuming that consumption and other issues are about the same
What does it prove? That over XX duration, in XX engine, in XX service ....XX40 oil produced lower wear numbers when compared to XX30 oil
...and that's about it.
Assuming that all other values were acceptable (flash, TBN, SUS, insolubles, etc.) ..it would appear to be a no brainer what choice to make.
...but the topic header is somewhat BS. Viscosity may or may not impact wear. Improper viscosity may or may not have impact on wear. Proper viscosity may or may not produce elevated wear. It's just too numb a statement without qualifications.
I think that everyone agrees ..regardless of origin ..that in the terms of wear metal particles ..less is always preferred to more.
Whether they have ulitmate practical impact on longevity is the only thing uncertain. Sure, I'll buy the "disturbing of established protective boundary layers" possibility ...I'll also buy the difference between particle suspension, retention, AND production.
There's a whole lot of data that doesn't just neatly fit into a box here. We see "switch hitters" have mixed results when going to something like RL ..yet we don't for some GC users (although on a side note ..virtually no one ever subjects any oil to any "endurance" runs and tend to form "projected" opinions based on limited short duration results.).
So we all can somewhat agree that UOA data is always going to be comparitive data and needs far too many data points to be "authoritative and comprehensive" to any but the most experienced (Terry and the like).
..but..no matter how you shake up the "what if's" and the "ya ..buts" ...is there anyone here who would continue to use an oil that produced MORE wear metals over another?
Take my situation. 10k M1 xw-30 78 ppm Fe compared to D1 for 10k @ 28 ppm (plug in any oil you want). Which oil am I gonna choose assuming that consumption and other issues are about the same
What does it prove? That over XX duration, in XX engine, in XX service ....XX40 oil produced lower wear numbers when compared to XX30 oil
...and that's about it.
Assuming that all other values were acceptable (flash, TBN, SUS, insolubles, etc.) ..it would appear to be a no brainer what choice to make.
...but the topic header is somewhat BS. Viscosity may or may not impact wear. Improper viscosity may or may not have impact on wear. Proper viscosity may or may not produce elevated wear. It's just too numb a statement without qualifications.
To me engine wear occurs when the oil film thickness is less than the height of the asperities of the bearing surfaces and/or the suspended particles are larger than the film. Otherwise the surfaces would essentially never touch and theoretically there would be no wear. No current motor oil would be too thin.
Bearing clearances have changed little over the years but the asperities have been minimized allowing thinner oils to be used. There are many advantages to making clearances smaller now:
Reducing the amount of Lubricating Engine Oil by Using a New Crankshaft Bearing with Eccentric Oil Groove, Shimura et al. This allows for reduced engine friction and a reduction in the size of the oil pump therefore increasing engine efficiency.
I do not have a reference but thicker oils can act as solids in bearings causing tremendous wear. I will work on my source.
From: Mechanical Engineering Design, Shigley et al: The change from hydrodynamic to boundary lubrication is not sudden or abrupt. It is mixed and as the surfaces move closer together, the boundary-type lubrication predominates. The viscosity of the lubricant is not of much importance with boundary lubrication as is the chemicals and composition.
He goes on the say that solids as graphite and molybdenum disulfide may lubricate and that current technology is to study these very chemicals.
My point is that today's additives allow us to use thinner oils and still minimize wear, even to the point wear is less from the additive than from the base oil.
And there are always new additives being developed:
A study on the Tribological Performance of an Organic Cadmium Compound as a Lubricant Additive, Jianqiang et al:
Cadmium diisopropyldithiophosphate possessed good antiwear and load carrying capacities when used in lubricant formulation. It provided better tribological properties than traditional ZDDP, and SbDDP. Moreover, it exhibited excellent extreme pressure properties as in a lithium complex grease.
aehaas
Bearing clearances have changed little over the years but the asperities have been minimized allowing thinner oils to be used. There are many advantages to making clearances smaller now:
Reducing the amount of Lubricating Engine Oil by Using a New Crankshaft Bearing with Eccentric Oil Groove, Shimura et al. This allows for reduced engine friction and a reduction in the size of the oil pump therefore increasing engine efficiency.
I do not have a reference but thicker oils can act as solids in bearings causing tremendous wear. I will work on my source.
From: Mechanical Engineering Design, Shigley et al: The change from hydrodynamic to boundary lubrication is not sudden or abrupt. It is mixed and as the surfaces move closer together, the boundary-type lubrication predominates. The viscosity of the lubricant is not of much importance with boundary lubrication as is the chemicals and composition.
He goes on the say that solids as graphite and molybdenum disulfide may lubricate and that current technology is to study these very chemicals.
My point is that today's additives allow us to use thinner oils and still minimize wear, even to the point wear is less from the additive than from the base oil.
And there are always new additives being developed:
A study on the Tribological Performance of an Organic Cadmium Compound as a Lubricant Additive, Jianqiang et al:
Cadmium diisopropyldithiophosphate possessed good antiwear and load carrying capacities when used in lubricant formulation. It provided better tribological properties than traditional ZDDP, and SbDDP. Moreover, it exhibited excellent extreme pressure properties as in a lithium complex grease.
aehaas
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And that is exactly where pour opinions differ, buster. I don't care if an oil shears as long as it retains the proper HTHS viscosity when it's needed most -- at a time when hydrodynamic lubrication is about to fail. Sure, I'd rather have an oil that doesn't shear much (or thicken) during its lifetime, but when purchasing an oil, I have to go by its specs, which are contained in the car maker's engine-specific specs and the oil's spec sheet. What I still am, and have been saying all along, is simply that nobody should use any oil that does not meet the minimum HTHS requirements.
Gary Allen - ..but..no matter how you shake up the "what if's" and the "ya ..buts" ...is there anyone here who would continue to use an oil that produced MORE wear metals over another?
Until there is some correlation developed between wear metals in a used oil analysis and actual wear in an engine no one would have a basis upon which to decide. One could assume that wear metals in a used oil analysis indicate actual engine wear but it is just an assumption.
Maybe some oils break down larger particles into smaller particles and they show in the used oil analysis. Maybe some oils tend to bind smaller particles into larger particles and they get excluded from the used oil analysis.
I don't know the answer but to see decisions made on the basis of wear metals in a used oil analysis is at best based on an undocumented assumption. We think we are doing the best for our engines, maybe we are, maybe?
Until there is some correlation developed between wear metals in a used oil analysis and actual wear in an engine no one would have a basis upon which to decide. One could assume that wear metals in a used oil analysis indicate actual engine wear but it is just an assumption.
Maybe some oils break down larger particles into smaller particles and they show in the used oil analysis. Maybe some oils tend to bind smaller particles into larger particles and they get excluded from the used oil analysis.
I don't know the answer but to see decisions made on the basis of wear metals in a used oil analysis is at best based on an undocumented assumption. We think we are doing the best for our engines, maybe we are, maybe?
You have raised some interesting and valid questions.
Until they are answered, I'm going to go with the best information I have and some semi-educated guesses and pay a reasonable amount of attention to used oil analysis results.
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Oxidation stability may be better in higher HTHS oils, as concluded by this article: http://www.practicingoilanalysis.com/article_detail.asp?articleid=649&relatedbookgroup=OilAnalysis
Oils with the European specification ACEA A3/B3 and B4 had good oxidation stability. However, oils with the specification ACEA A1/B1 and with high temperature, high shear (HTHS) viscosity of less than 3.5 megapascal seconds (cP) displayed rather poor oxidation stability (oils E and F in Figure 2).
Oils with the European specification ACEA A3/B3 and B4 had good oxidation stability. However, oils with the specification ACEA A1/B1 and with high temperature, high shear (HTHS) viscosity of less than 3.5 megapascal seconds (cP) displayed rather poor oxidation stability (oils E and F in Figure 2).
I agree and would use one that is specified by the manufacture as well. Whether it's a 20wt with a HT/HS of 2.8 or A3 3.5, using what is recommended is a safe bet.
Interesting, thanks for that link. I have to say though, why does Amsoil thicken out of grade much more then Mobil 1, yet Mobil 1 has a lower high temp/high shear for the Xw-30 wts?
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No idea, buster. Maybe one of our tribologists knows?
Sorry I forgot. But this brings up an interesting question. What was the oil like after this 3k drain flush. I wish we had this data also.
I wonder why they compared A1/B1 oils vs. the A3/B3 oils. I thought the A5/B5 standard was comparable to the A3/B3 standard with the main difference being viscosity...
Gary Allen - I would like to point out ...that virtually all of the break-in used oil analysis have highly elevated metal content. This, at least, suggests that there is some correlation between metal ejecta and UOA indications.
Excellent indicator.
Excellent indicator.
Hi,
and, refering correctly to break-in used oil analysis, why the 3MP Mobil 1/Amsoil results need very careful analyis.
Any use of the "raw" figures as was recently suggested by Tooslick in another thread IMHO is premature
Some petrol engines may take up to 50+k kms to fully break-in (before wear metal uptake stabilises). I have seem many heavy diesel engines go out to 200+k kms (I have had one go out to 300k kms) before wear metal uptake finally stabilises
Euro heavy diesels need at least 80k kms to reach stabilistion
This longer bed-in period sometimes seems to be engine specific rather that engine family specific and does not always mean a longer lifespan
Regards
Doug
MY02 Subaru Outback 2.5 manual (Delvac 1)
MY98 BMW Z3 2.8 manual (Delvac 1)
MY89 Porsche 928 S4 Auto (Delvac 1)
and, refering correctly to break-in used oil analysis, why the 3MP Mobil 1/Amsoil results need very careful analyis.
Any use of the "raw" figures as was recently suggested by Tooslick in another thread IMHO is premature
Some petrol engines may take up to 50+k kms to fully break-in (before wear metal uptake stabilises). I have seem many heavy diesel engines go out to 200+k kms (I have had one go out to 300k kms) before wear metal uptake finally stabilises
Euro heavy diesels need at least 80k kms to reach stabilistion
This longer bed-in period sometimes seems to be engine specific rather that engine family specific and does not always mean a longer lifespan
Regards
Doug
MY02 Subaru Outback 2.5 manual (Delvac 1)
MY98 BMW Z3 2.8 manual (Delvac 1)
MY89 Porsche 928 S4 Auto (Delvac 1)
I don't have the link, but I do recall running across one older paper on wear and UOA where they mentioned that non-detergent oils seemed to produce fairly reliable UOA wear indicators, but the results were mixed and not reliable with detergent oils. Other papers on anti-wear film structure noted which metals were detected in the films, and based on that it seems reasonable to assume that anti-wear films do not have perfect selectability on which metals get incorporated. Some of the films also seem to get generated under specific conditions and have different durability. The net result seems to be that the films generated, some desired and others not, act like storage capacitors for some metals, and fresh oil seems to disrupt some of the films. That's why people observe 'old oil produces less wear than fresh oil' when observed with either used oil analysis or trace analysis. That's also why wear seems to be monitored with other techniques like mass loss, dimensional differences, visual (microscopic) observation, etc.
A point to clarify....if you account for the possibility of films acting like metal stoarge capacitors then some studies using trace analysis for analysis can produce some convincing wear indicators. An example would be using adding an oil, 'running it in', and then varying load to see what indicates wear. The same technique wouldn't be as reliable for comparing different or even old vs fresh oil, due to the possible wear film disruption.
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