Mercedes on used oil analysis

[vinu_neuro]

3.7.1 Used oil analyses for early damage recognition by
determining abrasion elements

Attempts for early damage recognition are based on
determining abrasion elements, such as e.g. iron, copper,
chromium, etc.
The Service Companies will encounter difficulties when
evaluating such an analysis. Limits to be used are not only
dependent on the analysis method used (often differs from
laboratory to laboratory), but also on the type of engine
used (knowledge of components necessary), on the oil
change interval driven, on the type of oil, on the fuel and
not least also on the operating conditions.

Such evaluation problems often lead to uncertainty or to
improper responses.
It is also very important to take a proper sample. It has to be
taken from the oil circuit when the engine is running. A
sample taken from the oil sump often results in incorrect
analyses as a result of the residues which are present in the
sump.

3.7.2 Used oil analyses as an aid to workshop practice

Used oil analyses may be sensible if they are needed to
identify undesired components in the oil, such as fuel,
water, glycol or sand/silicon.
It is possible to react at short notice and possible damage
can also be avoided or rectified.

 

[Quattro Pete]

Well, in general, I believe that sums up nicely what most some of us think a value of a $20 oil analysis provides.

 

[vinu_neuro]

From what I've seen probably less than 10-15 users on this site understand the lack of significance of these cheapo UOA's.

 

[Quattro Pete]

Originally Posted By: vinu_neuro
From what I've seen probably less than 10-15 users on this site understand the lack of significance of these cheapo UOA's.

Fixed.

 

[CMMeadAM]

It would be interesting to hear the procedure by which
the oil sample "is taken from the the oil circuit when
the engine is running"............

 

[dparm]

Originally Posted By: CMMeadAM
It would be interesting to hear the procedure by which
the oil sample "is taken from the the oil circuit when
the engine is running"............


I would assume you can just thread a tube down the dipstick hole and pump some out. Their point is to just do it while the motor is running and the oil has come up to temp.

Whenever I pull a half-OCI sample, I do it immediately after a 20-30 minute drive.

 

[vinu_neuro]

They don't want samples from the sump. If you know which small ports are off oil galleys this should be pretty straightforward. There are at least two on the head in my Prelude that I can use for this. Still doesn't mean I'm going to use one of these UOA's for anything more than TBN/TAN observation 99% of the time.

 

[JHZR2]

That is interesting, because I cannot imagine that it is easy to get in and pull a sample on most MB engines.

Generally the best Ill use a UOA for is viscosity, TBN and antifreeze components. However, I feel that we can read more into it, especially if a trend is seen. Comparing one oil to another has so many variables that it can be quite dangerous, unless EVERYTHING is consistent, which it will never be on a single vehicle UOA set from oil sample to sample.

But across multiple dimensions, like we can see by going through tons of UOAs, like seen on here, we can infer something. Whether it means the difference between 100k and 500k is not really in the scope of capability. But it may make some feel good to try to optimize their oil selection.

In the end all, though we cannot see for certain, oil x will absolutely be better/worse than oil y. What it means in the long run is another story.

 

[hattaresguy]

I don't really get the point of UOA's unless your trying to identify a problem like coolant getting into the oil.

If the engine sounds fine and has good oil pressure its fine.

 

[CMMeadAM]

It just might be because some folks have much more intellectual curiosity than others and desire knowing
more about something than just blindly accepting it.

 

[d00df00d]

Originally Posted By: CMMeadAM
It just might be because some folks have much more intellectual curiosity than others and desire knowing
more about something than just blindly accepting it.


I suppose even a cheapo UOA does reflect more intellectual curiosity than no UOA at all, all else equal.

Whether it's fruitful is another story and depends on thinking critically about a lot of factors, as the OP describes. Very often, people who question the condition of their engines end up failing to apply the same questioning attitude to the UOA results (or others' interpretations of them). However, I think you're quite right to point out that the intent is worthwhile in and of itself.

 

[Quattro Pete]

Originally Posted By: JHZR2
That is interesting, because I cannot imagine that it is easy to get in and pull a sample on most MB engines.

It can be easily done through the oil dipstick tube.

 

[CMMeadAM]

That "easily" draws oil from the SUMP...which was specifically stated was NOT to be done in the commentary from MB.....it STILL would be interesting to hear the procedure by which
the oil would be sampled from the oil circuit and NOT from the sump while the engine is running.......and....."ports in the
engine block" won't cut it...........

 

[Cujet]

I'm not sure the engine has to be running. A sample taken mid stream from the sump drain plug is as valid as anything else. With the possible exception of a stationary, low RPM engine that has known stratification issues in the sump.

I don't put much faith in UOA's unless they are done in a scientific manner. Same oil every time, same interval every time, same operating conditions every time. Sampled throughout the engines life.

We've all seen trashed engines with acceptable UOA results. Especially the VW's.

 

[fdcg27]

Are you saying that an oil that shows consistently good UOAs versus one that shows consistently mediocre ones in a variety of applications is a better oil?
I would tend to agree with that.
Now, I've got a snapshot UOA coming of our older Accord after 6K on its third current run of PP.
I'm curious to see what there is to see, but I realize that one UOA on a vehicle that's done 197K is more a matter of entertainment than information.
Still, if nothing appears out of line, I'll at least feel reassured that replacing the transaxle, which never shifted quite right in the 130K we've had the car and finally locked up, was worth doing.
There is value in having one's assumptions confirmed.
I assume that the engine will be just fine for some time, based upon how it runs and its fuel and oil consumption, about 30 mpg average and a quart of oil after 4K.
A UOA may or may not validate my assumptions.

 

[buster]

Quote:
Generally the best Ill use a UOA for is viscosity, TBN and antifreeze components.


I agree. I also agree with MB opinion on the subject.

 

[OVERKILL]

Originally Posted By: Quattro Pete
Well, in general, I believe that sums up nicely what most some of us think a value of a $20 oil analysis provides.


Amen!

 

[Ayrton]

Isn't it true thought hat a manufacturer isn't going to want to do much because of Joe's oil analysis?

It seems this wording and position could simply be to prevent them from having to react to a spiked UOA.

 

[INDYMAC]

It always amazes me how so many BITOGER's with little to no confidence in the usefulness of UOA's and VOA's find their way into the VOA and UOA sections of BITOG, and they even take the time to post something derogatory about the poster for posting a report, the validity of the report, or how the poster uses information gained from the report. Can someone please explain this phenomenon?

 

[OVERKILL]

Originally Posted By: INDYMAC
It always amazes me how so many BITOGER's with little to no confidence in the usefulness of UOA's and VOA's find their way into the VOA and UOA sections of BITOG, and they even take the time to post something derogatory about the poster for posting a report, the validity of the report, or how the poster uses information gained from the report. Can someone please explain this phenomenon?


The idea is to keep the information on this board factual. Others would apparently like to live in a land of make believe with unicorns and pixies and UOA's that can tell you what oil is the best for your engine and at what rate your engine is wearing.

Many of us do UOA's for their intended purpose: To check for contamination and monitor oil life as well as watching out for any strange anomalies that may be signs of a mechanical issue.