Are we kidding ourselves judging motor oils by UOAs?

[fuel tanker man]

I think Too Slick makes a cogent argument.

The interpretation of the UOA would have to be rooted deeply in the knowledge of the engine and circumstances from which the oil came--as well as of the particular oil at hand.

High iron on one engine may mean nothing; in another it could be sounding the death knell. What may look like high silicone in a particular drain may actually have been part of the original oil recipe--one would have to know that. And oil recipes are a swiftly moving target these days--are they not?

With a good data base of what is to be expected from a given engine and a given oil, a better idea of what is going on could be had. Tall order, certainly. Pert near impossible order.

Norfolk Southern railroad uses Gulf oil (yeah, they still make it) in their locomotive engines, and they use UOA's to decide when to change the oil. They're using the same oil in the same basic engine designs, so they obviously have a firm data base for accurate interpretation of the results.

We see the "universal averages" column on most UOA's. I assume this is the average for all engines. Am I wrong?

If that is indeed the average for all engines, that's an almost useless number in my opinion. Further, it wouldn't take into consideration all oils either, some of which may have some of those elements built into the formula (as alluded to earlier).

All of this tends to point up even more the amount of talent (augmented by data specific to the engine and oil at hand) which must go into the proper interpretation of a UOA.

Perhaps we tend to over-simplify things.

When looking over UOA's at this forum and others like it, we often have little or no equal comparisons from which to draw conclusions.

After considering this issue carefully, I don't think UOA's are pointless--I just think that the proper interpretation of the UOA is a much deeper science than many of us (certainly me) have heretofore thought.

Dan

 

[DJ]

I think most of us realize there is more to this than just low numbers in certain elements that is why so many here not only use Blackstone but then have Terry look over the numbers.

 

[MNgopher]

quote:

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Originally posted by fuel tanker man:


We see the "universal averages" column on most UOA's. I assume this is the average for all engines. Am I wrong?

If that is indeed the average for all engines, that's an almost useless number in my opinion. Further, it wouldn't take into consideration all oils either, some of which may have some of those elements built into the formula (as alluded to earlier).

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The universal average Blackstone supplies is the average of all the UOA's they have on file for that particular motor. Ie: My F150's have (had) the 4.6l modular V8 in them. When I get my UOA's back, the Universal Average is for ALL of the 4.6l V8 motors they have in their database.

My Jeep gets different universals based on Jeep 4.0l UOA's.

I will point out that there are definitely anomolies in the database (for example, my Jeep 4.0l was originally put in with the Ford 4.0l v6 numbers. I let blackstone know and it was immediately fixed.).

Its also sometimes tough to kow how long mileage wise the average is for a universal average. In general, it seems to be in the 4000 mile range for most cars.

At a minimum, it provides the large group to get a rough comparison that we as individual car owners can never get owning one vehicle. I see it as a comparison point to see if something seems way out of line for that motor.

All in all though, nothing substitutes for long term trending for your own particular situation....

 

[Gary Allan]

quote:

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Norfolk Southern railroad uses Gulf oil (yeah, they still make it) in their locomotive engines, and they use UOA's to decide when to change the oil. They're using the same oil in the same basic engine designs, so they obviously have a firm data base for accurate interpretation of the results.

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This is where commercial/industrial applications have the advantage over us plebes. They are spec'd ONE oil over their entire lives. Diesels OTR engines typically (note the "typically" qualification, please) have two and only two weights to run, 15w-40 and 5w-40. Hence it comes down to "brand" if the manufacturer doesn't spec ONE BRAND of oil. To them the UOA merely detects problems (coolant, etc.) and determines if the oil is suitable for continued use. The conditions of operation are pretty much dictated by the narrow scope of their design application. You don't drive a 480 CAT for a 10 mile commute or play soccer mom with it.

So in their case .."the wear is ..what the wear is".

OTOH, if wear metals had absolutely NO basis as an indication of wear ...why in the heck do labs, universally, include wear metals in the report? If there's nothing to it ...and all the information that is "real" is TBN, moisture, fuel, oxidation, nitration, TAN, visc, and flash point ...then why bother??? It would appear to be the biggest waste of lab time ..over the longest duration of history ..for a "non-issue" ..wouldn't you say??

 

[1sttruck]

There still seems to be a lot of hidden assumptions being used. If we get more specific then we'll probably end up with more agreement.

'Used oil analysis is a reliable measure of wear' - Not, for several reasons, but the biggest one is that the statement is too general. UOA will not indicate how much mass loss there is among three different bearings each using oils of different viscosity. The Shell data that someone posted indicated that, duh, there is less wear with heavier viscosity, and not as much wear reduction when using oils heavier than 40W. But, lots and lots of people jump up and down and say that their UOAs shows very little wear, in fact I'd guess that they'd be pretty similar. That's one reason why I guess you don't see as many UOAs in wear and friction studies.

'Used oil analysis is a useful indicator of wear in a maintenance program' - Yes.

 

[Gary Allan]

Okay, I was hoping you would dwell on this a bit.


1sttruck. Even if I had a vast data base of one specific engine over many installations/applications (let's say diesel/electric locomotives for the sake of debate here), what would the presense of higher or lower wear metals mean to me ...if I'm ONLY determining if the OCI is correct and/or the oil is suitable for continued use?? If it has no correleation to "wear" (however you define it - I would rather use the term "decay") ..then what possible use could the data be to anyone??

What I'm trying to extract from you is a plausible explanation for the wear metal testing ..if, by any and all accounts, the data is worthless for indicating wear.

That is, why do you think it is done? I believe you've gotten so intent on questioning the accuracy and validity of wear metal indicators that you haven't applied an equal amount of effort to providing alternative value to them.

The example I would use is the assumption that a bypass valve in an oil filter is somehow integrated into the oil flow/pressure scheme and custom detailed to your particular engine. In my ponderings of the topic ...I was led to the alternative believe/suspiscion that it was merely to protect the media from insult.

That is, I swapped one paradigm for one that I thought had a more probable validity.

Do you have any such alternative "worth" to offer for wear metal testing??

 

[Jay]

quote:

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Originally posted by TooSlick:
..You'll also see more bearing wear if you use an oil too thin for the application...

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I've often wondered about this statement. I've seen it many times on this board, but in SAE paper 1999-01-3468, the researchers were studying low and ultra-low viscosity oils, and were trying to see how low in viscosity they could go before excessive wear became a problem. They were formulating various weights of oils with standardized add packs and studying wear after an extensive (and expensive sounding) test sequence.
They examined only valvetrain wear in the test. The inference is that the valvetrain is the most vulnerable item if viscosity gets too low. Or maybe that was the easiest thing to measure, since they did their wear measurements by disassembly and inspection.

I suppose I could write them and ask.

 

[1sttruck]

In the context of a maintenance program wear metals are a valuable indicator of possible problems. As a reliable measure of wear, say bearing mass loss in the qualification of a new lubricant, it will not be reliable for what I think are obvious reasons.

Wear metals detected in a UOA are a subset of the mass of material lost by the engine. Some of the really big stuff ends up laying somwhere in the engine, hopefully caught in a screen. Other mass ends up being transferred to mating parts in the event of scuffing or partial seizure. Smaller particles, which during break-in are typically very numerous, end up either being trapped somewhere in the engine or caught in the filter. I'll guess that the mass of these particles, which aren't being measured in a UOA, dwarf the mass of the wear metals that are being measured in a UOA.

During the life of an engine wear will tend to display a classic bathtub curve, with high wear during break-in, a low level during normal life, and increased wear towards the end of life. At the conclusion one often ends up with a film, be it anti-wear, sludge, varnish, etc., which will also contain wear metals. Somehow you need to 'integrate the area under the curve' over the life of the engine, using a unknown portion of the mass, in an attempt to estimate total mass loss. With each oil change you drop the wear metals, and it will increase at different rates depending upon use, conditions, etc. I think that there are too many unkowns, which I guess is why one doesn't see wear metals from UOAs as a substitute for mass loss and other techniques in determining wear.

If you want to know the condition of the oil and when to change it the wear metals are an aid in that decision. If you want to increase your chances of detecting problems then a UOA can be a valuable indicator, and it appears that the data is typically trended. If you want to compare different conditions or lubricants it appears that at a minimum you should also be tracking particle size and distribution, but you're taking on additional risk unless you address other possible problems that may not be not detected in a UOA.

We've seen some mention that when using Redline they exhibited high wear metals, and that the metals dropped to low levels after an engine clean. Observations like this support the hypothesis that films inside the engine contain potentially a lot of wear metals, which are then dissolved by some oils and resuspending the wear meatls. Some oils may create films that incorporate wear metals, effectively hiding then from detection. Some oils may trade wear in one part of engine for wear in another, and difference may be masked by a similar wear metal level.

 

[Gary Allan]

quote:

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I'll guess that the mass of these particles, which aren't being measured in a UOA, dwarf the mass of the wear metals that are being measured in a UOA.

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Why? That is, what leads you to this belief? I'm not disputing it ..just wondering where your "guess" came from. What convinces you that it's not the opposite?

quote:

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in an attempt to estimate total mass loss.

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Why would one have to? Would it invalidate a UOA for determining comparitive rates of wear simply because you can't plug in a given known bearing surface and say "Ah-HUH! If this engine continues on like this ...I've only got 189,294 miles of life before catostrophic failure!!" ???

quote:

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which I guess is why one doesn't see wear metals from UOAs as a substitute for mass loss and other techniques in determining wear.

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Why does it have to be??

When I did boiler feed water test for iron content, I didn't know how much mass Fe was lost. I only knew that above a certain level, it was deteriating the boiler beyond acceptable levels. It was a condition that needed to be corrected or undue life reduction was taking place.

If all you are saying is that wear metal indicators aren't any good at plotting the life expectancy of an engine ..then I have no arguement at all. There is no way that every engine ..with all the different surface areas that vary from engine to engine could possibly boil down to "if you have 2 ppm of Pb per 100 miles ..you've lost .000002 of your bearing surface in all your bearings. There would be no way to know if the metal was produced from one defective (impurity/integrity) bearing ..all normal bearings or whatever. We don't know the difference between a SBC and a Vulcan 3.0 ..or a Detroit Diesel. We don't know if it has 150^2 of bearing surface ..or 350^2 of bearing surface.

You can't tell the life expectancy of a human by testing their colesterol, trigylserides, or a number of other blood chemistry items ..but they are things to be monitored, and if necessary, modified. Just like a human, the life expectancy is in the design and is pretty much cast in pretty firm material. Beyond basic design integrity ..everything else is in the form of "free radicals" that detract or detune that design life cycle.


I see a recurring reference to RL and the effect of its MEGA dosed additive package wreaking havoc with UOAs ...yet no other oil seems to do this. This oddball singular instance is used as some basis to discount a vast number of "typical" results over a vast number of oils that do not share this unique aspect to them. To me it's like twisting one screw a quarter turn ..and saying that, instead, the rest of the universe just rotated 90° as though it was THE focal point of existance.


This is still too nebulous a theory for me to not use UOA as a wear indicator. I don't know how many tons of H20 are in the immediate region either without measuring the confines of the effect..but I still look at the relative humidity needle.

 

[1sttruck]

Gary Allan said "If all you are saying is that wear metal indicators aren't any good at plotting the life expectancy of an engine ..then I have no arguement at all." and "This is still too nebulous a theory for me to not use UOA as a wear indicator. I don't know how many tons of H20 are in the immediate region either without measuring the confines of the effect..but I still look at the relative humidity needle."

It appears that we're in agreement. Your two statements show the difference between 'Wear metals in UOAs are a reliable measure of wear' (Not), and 'UOAs are a valuable indicator of wear in a maintenance program' (Yes). I don't think that we can use 'reliable indicator of wear' as there are more than a few reported problems that were not detected by UOAs. To me at least, there is a huge difference between the two statements, but it doesn't seem like it's obvious so I'll back up a bit.

Why do you use a specific oil in a vehicle ? If it's primarily for fuel economy or performance at the expense of engine life then why would you be concerned with wear anyway ? Use the oil that gets you the desired fuel economy or performance, don't worry about wear, and be done with it. If you're a little concerned about wear even though you're primarily interested in fuel economy use what the maker recommends, and if a little concerned about wear even though you're primarily interested in performance use what others are using.

If you're using a specific oil in a vehicle in an attempt to get maximum engine life, then you should be concerned about wear. A qualifier here is that most people are probably trying to get maximum engine life as part of some sort of cost/benefit tradeoff, either as a hobby in trying to beat the 'no brainer' OEM recommendations that will get them to some average life, or for business reasons. But if we're trying to use UOAs in an attempt to obtain maximum engine life we have a problem don't we, as we both agree that wear metal indicators aren't good at determining the life expectancy of an engine. See the following link, which I posted in another forum, which shows the impact of extending oil changes too far. The article makes the case that particles are the primary reason for increased wear, but particles aren't measured in most (almost all ?) UOAs reported in this forum. There's also kind of a 'you're evil if you don't extend your oil change interval as much as possible' mentality in this fourm, doubly so if you're using synthetic oil, but the chart again shows the long term downside of pushing oil change intervals too far. How many are making decisions to extend oil change intervals only based on wear metals in a UOA, and doing long term damage in the meantime ? The metals in UOAs don't even appear to be a relaibale wear rate indicator, in part because all of the wear metals are not being measured, but also because of the surface films tha aren't being addressed.

http://www.practicingoilanalysis.com/backup/200211/Editor-Fig3.gif

My engine make, Cummins, states that you can't extend oil change intervals merely because you're using synthetic oil, bypass filters, or doing UOAs. Looking around different aircraft and boat sites it's initially surprising that you read comments that using mineral oil instead of synthetic oil usually produces fewer problems. Mercruiser flat out states that you can't use synthetic oil. I guess it's because they've experienced too many problems with poor decisions made using UOAs. Again, as part of a maintenance program when trended UOAs are a valuable indicator of possible problems, but we both agree that using wear metals in a UOAs isn't a good measure of engine life.

Also, 'surface active films' seems to be well understood in industry, where elaborate flushing procedures are used when changing oils in tests. Even at this site it's very evident, just look at UOAs perfomed while doing AutoRx cleaning. Most people don't even do UOAs while using AutoRx as they KNOW that they'll be flushing out lots of debris. Mobil 1 also produces high wear metals when flushing out thick films, see below.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002072

 

[Mike_dup1]

quote:

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Looking around different aircraft and boat sites it's initially surprising that you read comments that using mineral oil instead of synthetic oil usually produces fewer problems.

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What a crock.........

 

[1sttruck]

synthetic oil & aircraft....

http://www.avweb.com/news/maint/182909-1.html

http://www.aviationtoday.com/cgi/am/show_mag.cgi?pub=am&mon=1200&file=1200piston.htm

http://www.copanational.org/non-members/safety/2001/safetyPPJune01.htm

 

[Terry]

Dan, you are a wise man.

"After considering this issue carefully, I don't think UOA's are pointless--I just think that the proper interpretation of the UOA is a much deeper science than many of us (certainly me) have heretofore thought. "

I have been trying to get this across to the " I'm on the internet therefore I can know anything crowd" for years.

Terry

 

[TooSlick]

I think the key is you need to get yourself a set of those special Tarot cards that Terry uses to interpret the data ...

TS

 

[1sttruck]

I agree with Terry's last reply, and I think I've stated as such previously. For the elevententh time, no one will deny the value of UOAs in a maintenance program, they're often trended and complemented with other tests like particle distributions. My objections are with the recommendations affecting engine life where no other measures have been considered, and especially with the comparisons like 'the brand and grade of oil has been changed every 5k miles, and per the UOA perfromed at each oil change we can prove that oil x produces 2.4 time less wear than oil y because the Fe is 2.4 times less.' Even data in this forum indicates that such measures aren't reliable due to the films that aren't accounted for, whether it's more common stuff like varnish, deposits or sludge, or less well know stuff like 'surface active films' that are flushed during more formal testing. It's also not reliable due to the particle counts aren't typically accounted for. We've seen good UOAs on engines that were starting to sludge up, and poor UOAs on engines that previously measured good, the oil was changed, now measure bad, the engine was cleaned and now measure good again. The films confounded the wear determination as the oil was implicated but after a cleaning it tested fine. As previously mentioned everyone 'knows' that AutoRx will produce high wear metals as it's evidently dissolving the metals locked up in the films, but for some bizarre reason people want to pretend that it won't affect their estimates of wear based on wear metals.

 

[Gary Allan]

quote:

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but for some bizarre reason people want to pretend that it won't affect their estimates of wear based on wear metals.

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I don't see this as a bizarre reason at all. Why would you assume that typical film formation, beyond its formation, alters the presense of wear metals? Please exclude RL from the example.

Why would you lean toward the suggestion that the upramp of wear metals is a result of film disruption and not the end of film formation? Again, please leave RL out of the example.

I'll agree that the switch hitters here are mostly determing if the oil didn't get beat up during the OCI.

Suppose you don't switch hit?

Suppose I don't have any sludge ..or this or that?

Suppose I changed my oil ever 2 weeks or 500 miles for 2m/2kmiles and then did a UOA on the 500, 1000, 1500, 2000, 3000 on the same sump..and it still showed the same upramp between 2k and 3k?

Have you thought of configuring a battery (I've tried) of BITOG capable tests that would support your position aside from quoting flaws in current "methods"??? Have you considered conducting such, albeit imperfect, testing yourself?

 

[Doug Hillary]

Hi,
with some decades of experience I feel comfortable with this summary of UOAs concerning engines

1 - Trending is critical for UOAs to be meaningful. Building the trends takes time - months/years to become truely meaningful
2 - Engine specific data (specific ppm limits and metallurgy data etc etc)is required for accuracy
3 - Specific oil data is required to enable an accurate balancing between the engine Manufacturer's and Oil Company's parameters
4 - They will NOT tell you data that will enable a "projected lifespan" to be proclaimed for an engine with much accuracy
5 - They will indicate cooling system, fuelling and induction issues but only if they are conducted regularly
6 - I have never seen them "predict" a major engine component failure via wear metal analysis - in over millions of kms and over some decades
7 - I have seen them assist in "predicting" a small component problem, but accuracy was only enabled via extensive user experience with the engine family concerned
8 - They will give an accurate summary of the oils health - both TAN and TBN reports are needed IMHO for accuracy. This will enable the programming of extended OCIs with safety and the early despatch of oil with perhaps fuel contamination and etc
9 - They will not enable a truely accurate comparison of one oil and another in an engine. Well, not unless it is clinically done and even then the variables will probably overwhelm the result
10 - and a few etc's

I have watched many Oil Company and Lab. based "experts" predict and advise users with great inaccuracy. And sometimes if you get lucky, with great accuracy too!

I have watched intelligent Owners/Service Managers fail to act on advice and "Warning" reports from UOAs. As many people are poorly educated on lubrication issues to start with this does not help understanding "new fangled technology"
I have seen much scrap metal accumulate from all of these situations

For me UOAs have been a great cost saving tool but I would never use them to prescribe a particular oil for an engine. Or, I may add to predict component life - yet!

I believe that already some components are being designed with wear trace components built in. This will enable some accuracy as to when these may need to be replaced - sadly much newer technologies than UOAS may beat them to it!

When this topic was vented here about a year or so ago similar comments were made from the people that have posted here this time

At least many BITOG listers still carry out UOAs for fun - as long as it is treated this way it is just that! As it should be for the non-Commercial user and perhaps they may identify an issue or two that can save them the cost

So IMHO to accurately answer the thread's leading question "Are we kidding ourselves judging motor oils by UOAs?" the answer is: YES!
(If used alone!)

Regards
Doug

 

[Terry]

1sttruck, you had me up to this statement :

" As previously mentioned everyone 'knows' that AutoRx will produce high wear metals as it's evidently dissolving the metals locked up in the films, but for some bizarre reason people want to pretend that it won't affect their estimates of wear based on wear metals. "

In every independent test we performed or interpreted for Auto-Rx we NEVER saw a meaningful increase in elemental wear levels or increased wear signatures , ever. Hundreds of field UOA's back that up. Even when the oil filter failed and was allowing trash to be reintroduced into the engine.

One of the reasons I am so positive about the chemistry is that while it cleans deeply and disperses better than any traditional low flash solvent it will not harm the metals/materials in the engine. I have NEVER seen RX damage metals of any kind.

Let me remind all that I interpreted data from many sources in bringing RX to market and proprietary screens of ASTM/SAE wear data were reviewed after independent testing from a major oil add company and many others were correlated to our field test data in on the road vehicles. Thats me (independent) looking at data not owned or controlled by Auto-RX.

Pardon me but your comments are another good example of not being able to properly interpret the data posted here. That data is not flawed, it is data from real engines/trans/etc. that have been in use. Now I will agree that the comments posted by most about what it all means just show that internet boards have a achilles heel AND it is tough without my TAROT cards to properly know what it all means.

Terry

 

[TooSlick]

I don't think it's that hard to make sense out of UOA's, but I've been doing it for over ten years and have looked at hundreds of samples. In addition, my technical background and work experience is in materials science and propulsion.

The key thing is you have to take all the variables such as operating conditions, contamination, etc into account in order to fairly evaluate how the oil is doing. There IS enough data posted on this forum that it's pretty straight foward to determine general trends amoung the more popular formulations. For some of the formulations that aren't tested that often, it's difficult to tell anything. For example, I haven't got a clue what the best performing petroleum oil is in a 5w-30 or 10w-30 grade. i'm not sure you could ever tell that if you're only running 3000 mile change intervals, since oil analysis results just aren't that accurate.

TS

 

[fuel tanker man]

Terry,

I'm still trying to learn...

If Auto RX doesn't release the trapped wear metals (as evidenced by the wear metals in the rinses not being abnormally high) then how can we say that Redline oil is cleaning out trapped wear metals?

Is Redline a more capable solvent than Auto RX?

Might it be a bad idea to introduce such a "stripping" solvent (if that's actually what Redline oil is doing) to a "seasoned" engine?

Or, could it be that Redline really is letting the engine scrape?

Dan