TAN or TBN

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Hi,
at least this discussion has shown some healthy viewpoints and raised all of our knowledge levels

Terry - I agree that both TBN and TAN results are desirable. I suppose you can get what you are prepared to pay for - even if the recipient may not fully understand the results. For the average user on here the TBN result is the best known - even both of them! But even the change from one to another TBN determination alone caused a bit of shock reaction here

ExxonMobil are not stupid and their move to TAN alone was probably a well balanced commercial and certainly a sincere technical decision. Their Engineers confirm this

Regarding fuel - Australia had high sulphur levels until about three years ago. At present they are now the same as in NA. Our heavy diesels use the Euro 3 & Californian emission standards. Our cars are also subject to emission legislation based on both Euro and NA standards

From my viewpoint please note the following examples in the use of TAN & TBN ( all Delvac 1 5w-40 - TBN to D4739):

Example 1
Truck A
At 9/5/00 - Engine at 126kkms ( average oil temp 103C )
Sample 1 oil @ 10kkms
TAN - 3.4
TBN - 8.0
Sample 2 oil @ 51kkms
TAN - 7.2
TBN - 2.6
Sample 3 oil @ 65kkms
TAN - 7.2
TBN - 2.0
Sample 4 oil @ 84kkms
TAN - 5.0
TBN - 2.1
Sample 5 oil @103kkms
TAN - 6.9
TBN - 2.4

We were tempted to change the oil at Sample 2 but the TAN and not the TBN reading at Sample 3 convinced us to let it live. This decision was justified as you can see by the later samples. We established an on-going OC interval of 100kkms - and averaged a 96kkms OC interval actual )
This engine has since reached almost 1mkkms ( 620000 miles ) and is about to be sold. It has had an average oil consumption of 1ltr/6.3kkms during its life to date

Example 2
Truck B
At 12/5/00 - Engine at 385kkms ( average oil temp 98C )
Sample 1 oil @ 86kkms
TAN - 8.5
TBN - 0.1
Sample 2 oil @ 94kkms
TAN - 9.1
TBN - 2.0

After Sample 1 we quickly carried out another UOA ( Sample 2 ) and even though the TBN had "restored" itself we drained the oil based on the TAN which had gone above our 75% of VOA based TBN limit. The TBN was still at our lower limit for survival

At 9/19/01- Engine at 561kkms
Sample 1 oil @ 88kkms
TAN - 6.1
TBN - 0.5
Sample 2 oil @ 92kkms
TAN - 6.8
TBN - 0.5

We elected to retain the oil based on the "suspect" TBN's and based on the relatively stable TAN readings

This vehicle was disposed of a year ago at 1mkkms without any "whole of life" engine issues at all and its oil consumption then had averaged 1ltr/6kkms ( 1 litre/3000 miles )

An oil and filter change on these vehicles costs $A400+ for oil ( Delvac 1 ) and $A100 for filters ( Donaldson ELF3998 ) which stay in place for the 100kkms OC cycle. We clean the Mann-Hummel centrifuge at every second OC. Add labour and the cost of an OC is about $A600+ plus down time!

So I believe in the end that it is all a case of interpretation and for most users on this Board as stated earlier the TBN result has more street credibility. This is probably based on "past practice" alone and more Labs may move to the TAN result alone in the future

Professional users need to use professional techniques at all times and I am sure most already do

It is great to know that so much Professional expertise exists on this Board

Regards
 
quote:

Originally posted by Doug Hillary:
Hi,
Robbie Alexander - TAN
-*-*-*


Thanks Doug. I am truly grateful to have a better understanding from your point of view. I can see, I think where youre comming from. I respect that side of the fence. Also, please note that I have only experience with the oil I use and sell... I have or I did forget about other oils and the problems they create. Maybe, maybe, just maybe, you may have a reason IMO to continue (if it were me!).
I wish I knew more so I could express myself properly, and I wish I could get into more detail about the lab and what is done with that TBN/TAN thing, but I can't, there are several things I'd like to say, but I don't know how...... RATSzzzz

All I know is I too have read (wrong or right) my reports. I too, have my own system (wight or wrong), that has worked for me. I have seen IN MY OWN experience that with my engines and my oil and my understanding, I don't need a TAN, I DO need a TBN - although not always....
The Labs TBN measurement is different than the MFG. The lab takes into account of the additives that are DEPLEATED and thus also in consideration the ACIDS too... I have seen my TBN always maintain a steady move, every once and awhile it will move more or will take off ie a problem, I plan on changing my oil when the TBN is high, because of the delay in lab reports and etc... my system has worked for me. The TAN, as I mentioned again, will move more at the last moment... I don't wait that long... I rather dump GOOD oil.

In my experience Wearcheck as ran TAN's when I have not requested, either based on the problems I was having or the problems I have had in the past... They JUST DID because they were concerned... anyhow, that saved my engine at the time... Maybe I'm wrong.

Again, I may not know who or what to look for in a UOA but Wear is KING there, WEAR speaks volumes for all the TBN or TAN or VISC or anything for that matter... I TREND my WEAR. WEAR is king, again, IMHO Wear is KINK in the UOA's. Normal
and abnormal wear can be effectively traced by monitoring wear metal levels at each drain. Hope I have not made anyone angry, but THAT in and OF itself has been MY KEY to saving a few serious problems.
Again, the TAN will only move when TBN is getting too low... IN GENERAL that has been what I see, every time I aked in the past about the TAN I would be told NOT necessary... ie everything else is OKAY, only when it is warranted, THEN run one... I'm no expert, and would like to know more but unless some one could compell me to change, I still see no need in it.
 
First, let me say that it is nice to see such a detailed discussion that is backed up with real data. I realize that I gave a simple answer to a complex question. I was feeling somewhat Republican last night.

TAN is a perfectly acceptable method for monitoring engine oil condition when used in a fleet management program as described by Doug. The determination is done by direct titration, so the values obtained are more robust than either TBN determination method. This is particularly true since most labs seem to have recently modified the methods used to determine TBN for reasons that I do not fully understand. However, in order for TAN values to be useful, you need VOA data on the particular oil that you are using. Since the detergents themselves are weak acids, all motor oils will have a native TAN that will increase over time as the oil is in service. So if you know what your starting point is, the % increase in TAN is a perfectly acceptable way to measure the lifespan of the oil. However, as an absolute value, it is not as useful as TBN when comparing DIFFERENT oils.

The relationship between TAN and TBN is going to vary between different types and brands of oil. Oils starting out with higher virgin TBNs, more robust additive packages (the specific type and amount of detergents and oxidation inhibitors), and more shear-stable base oils are going to be able to hold more acid than lesser oils. So from the perspective of a North American consumer oil analysis program, TBN is, at least in principle, the more useful measurement. As Terry points out, the average guy needs to know how much residual buffering capacity is left in the oil regardless of the brand and additive composition.

So maybe the Wearcheck guy is not confused. Maybe our northern brothers are aligning with Oz and the old Commonwealth nations in adopting a new UOA standard. Maybe, as is so often said to the rest of the world, the US will have to go it alone.
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Hi,

Robbie - thanks for your comments. I monitor wear trends but for us they are VERY predictable. Only once have we "panicked" - we had a 216ppm Iron against an engine's average of 90ppm ( limit 150ppm ). As the engine had had a cam failure under warranty and the UOA was done 14 days later we could hardly believe. It turned out t be a faulty repair!
Otherwise the elemental items are usually very stable and predictable

Drstressor - please don't "go it alone" we support the USA from Downunder you know

At times though we do tend to consider Euro trends as well and the Euro auto/truck market is strong here too ( I do not own an OZ vehicle all are Euro or American )

Regards
 
Patman, I am not trying to discredit what DRstressor is saying.I'm sure that he can show us lots and lots of thing, geez I'm so ignorant
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On the other hand he is not THE only source of knowledge.

This board is an incredible source of information, its also a huge source of opinion.

We are all trying to find the best oil and the best way to analyse what is going on in our engine.( we should also do this for our health but thats another story )
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On the other hand we are how many ? 3500 members on this board ?? A couple of hundreds participating on a regular basis ? Not really representative of the world outside.

If millions of car owner can get away with Fram and some house brand oil without having problem we may have a lot more to learn than we think ?

Why Wearcheck is ?....call them and let us know, they may have a good reason for it ? Maybe that will fall under the "you get what you pay for"
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I've read many post where you find people more confused after spending hours reading the board than they ever were before !!! Why, because no situation is exactly the same for everybody.What works for you may not work for me.

There is no perfect oil, perfect filter, perfect technician. By the time you know what is working on your car its too late to correct the damage made to it. You get a new one and you start all over again...

But I have to agree, it's lot of fun
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And sorry for my Frenglish, I know I should spend more time learning your language and less time to learn about oil...
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You make a good point Baveux.

It can be confusing on here sometimes, and there definitely are a lot of differing opinions on many aspects of motor oil, but it's still a lot of fun to wade through all the posts in any given day.

By the way, your English is perfectly fine, I never would've known it wasn't your first language if you hadn't mentioned it!
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Here is the explanation from the Wearcheck representative:

The TAN of a new oil is initially low but will increase with oil usage as the acid neutralizing additives in the oil are depleted. The rate of increase of the TAN starts off slowly but increases with additive depletion as the rate of neutralization become slower while the rate of acid contamination from blow-by remains essentially constant under the same operating conditions. Once the TAN of an engine oil reaches a value of around 4 it would be advisable to change the oil as engine wear is likely to accelerate if the oils acidity is allowed to increase further.



The TBN of an oil will decrease with oil usage and with Diesel engines it is a general rule that oil should be condemned for further use when the TBN has been reduced to half its starting value. The change in TBN with oil usage is more complicated that TAN and TBN values are also effected more by oil top up than TAN. Not all additives in an oil that contribute to a TBN value are effective acid neutralizers and it should be remembered that the neutralization process is fairly slow. It is therefore possible for an oil to have what appears to be a reasonable TBN value yet be acidic in nature and potentially corrosive to an engine.



With a Gasoline engine oil one could possibly allow the TBN to drop lower than half its value but how low one allows it to go will depend on the nature of the oil and its additive package. A TAN test will give you a better indication of when the oil has reached the end of its service life especially when considering the application you have in mind.


So ???
 
OK, now I flat out disagree. The same absolute value for TAN should not be used as an end point for changing all types of oil, particularly a value as conservative as 4. Many diesel oils start out with a TAN between 2 and 3 when new. Similarly, recommending a change after only a 50% drop in TBN with an oil that might start out at 11 or 12 is a waste.

quote:

Not all additives in an oil that contribute to a TBN value are effective acid neutralizers and it should be remembered that the neutralization process is fairly slow. It is therefore possible for an oil to have what appears to be a reasonable TBN value yet be acidic in nature and potentially corrosive to an engine.

There is a lot of misinformation in this statement. I don't understand how any additive that contributes to the TBN (i.e. a titratable base)cannot neutralize acid. And from a chemical perspective, the neutralization reaction is limited only by diffusion and is essentially instantaneous. A technician operating a titrator might get the impression that the process is slow, but the lag they see is due to the time required for mixing and for the membrane of the probe to equilibrate. This is just an instrumentation artifact. The neutralization reaction itself is very fast.

The only instance where I can imagine where used oil with a reasonable TBN might be lead to more corrosion than fresh oil is if the engine sits idle for very long periods after many short trips. Here, local depletion of anti-oxidants on drained metal surfaces allows more acids to form if moisture is present. So oil that already contains some acid will reach complete TBN depletion faster on the metal parts. This is not an issue for engines used in truck fleet service or in cars that are driven regularly. For example, 3MP's oil study did not find evidence for accelerated wear after the TBN dropped to low but stable values.

So I'm back to my original position. The Wearcheck guy is confused.
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quote:

Originally posted by Drstressor:

-*-*-*-*-*
The relationship between TAN and TBN is going to vary between different types and brands of oil. Oils starting out with higher virgin TBNs, -*-*

As Terry points out, the average guy needs to know how much residual buffering capacity is left in the oil regardless of the brand and additive composition.-*-*


Good post. And YES, the relationship between TBN/TAN depends upon the oil blend. Always keep this in mind. All oils do not respond here the same, even though in wear they may not look, IMO too far off... So I can see Dougs' point clearly, and I hope You'all see mine!

Also remember there are several ways to establish a TBN, and they are not equal, some COST more and last longer, holding back the TAN longer and so you can do a longer drain, while at the same time allowing the TBN to HOLD or be BOOSTED back to life and or continue on its trend to a point in time necessary for a Change.

Some oils, the TAN is not a real issue unless you are pushing the envelope, and I would never continue that for very many times if at all, depending upon circumstances. But this is where you have to know your Engine and habits and just EXPERIENCE... As in Dougs case, he seems like he has a plan that works or him. I advise everyone to come up with a plan, and stick with it.. I'm not saying not to TWEEK it, but any plan is better than no plan. Just like playing in the stock markets.

Also, I agree with Terry's position. IT's been told to me by several dozen people. In part I can claim it more than others because of experience with my cars and oil combo's. Some cheap oil's I would not go there, but again in general Yes, I agree.

Baveux:
"The TAN of a new oil is initially low but will increase with oil usage as the acid neutralizing additives in the oil are depleted. "

What first off is Low, or what are the starting points of TAN's? and why is LOW-er better?

Second, keep in mind it's not just the additives that hold the acids at bay, it too is the OIL itself.

Also, a good TBN will it not reflect this>?
BTW, what oil were we or you rather, talking about?
I think the lab guy may be CYA.
I have had several discussions with them, and been told... well anyway CYA.

I would suggest if you are concerned, then do this: Run at least three drain with the same oil, and then do at least three OCI's with the TAN included... push the second set OUT well into extended drains... and see!
 
Don't be confused. The advice from Wearcheck will not get you in trouble. They are just being conservative. And TAN and TBN are hardly ever relevant for automotive oils unless extended drains (>10,000 miles)are used. The oil typically goes out of viscosity specs or Si levels get too high before acid accumulation becomes a problem. The guys on this board like to look at residual TBN values when they compare different oils or try to push the limits of shear stable synthetics. But the information is unually not useful with normal change intervals except to flag coolant leakage. Here, either TAN or TBN will let you know if there if there is a problem as long as you are following trends. But so would the test for glycol.

[ January 08, 2004, 02:00 PM: Message edited by: Drstressor ]
 
Hi,
Drstressor - I agree with you that the conservative TAN/TBN numbers mentioned by Wearcheck are very misleading

If I had commenced using their parameters initially and many years ago I would have trashed many thousands of litres of usable lubricant, and wasted a lot of money

The environment would have suffered too!

As examples;
a) one engine had a TBN reading of between 2 and 3 for over 60kkms ( but no significantly rising TAN ). The VOA TBN was 11 - so we were operating way below the "half the VOA TBN" suggested by Wearcheck. Our absolute limit for TBN set by Engine and Oil manufacturers is/was 1 ( I used 2 ) This troublefree engine was sold at about 1mkms

b) The highest TAN we have recorded was 9.10 a long way above Wearcheck's recommended 4.
Our averaged TAN taken at the averaged OCI of about 90kkms is 6.67. The lowest averaged TAN at the averaged OCI was 5.94
As stated earlier, the limit we set for TAN is 75% of the VOA TBN

I have found that many UOA Lab. Technicians do not fully understand the task they undertake - its simply a job for them - and they have no real world experience to back it up. They simply apply set standards and I wonder who sets the parameters in "independent" Labs and how they are established. Of course they will be conservative!
In the major Oil Companies Labs it is usually the Senior Engineer.

Baveux - take Drstressor's advice - Wearcheck's advice is ultra conservative and it will not get you into trouble at all

Robbie - you say that you have difficulty in expressing yourself - you do very well indeed, please keep it up. I for one enjoy your input.
Being fluent and literate isn't always a sign of intellect,common sense,experience or knowledge!

Regards

[ January 08, 2004, 06:44 PM: Message edited by: Doug Hillary ]
 
Oh my ! Oh my ! Oh my !
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Very interesting feedback from you guys.

Tan, no tan, TBN dying and suddenly resurecting in some circumstances.

Too much information is like not enough, at the end I will have to beleive one of you, to take my own decision, and to hope for the best.

But I will have a little voice whispering to me Richard, maybe the other guy was right ...
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At least I was able to sleep before when I was using Fram and some cheap housebrand oil
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It's funny how sometimes we are trying hard to screw up things.

Its so safe to change the oil at 5000km with dino, or 10000 km with sysntetic.

I wonder why we are trying to live on the edge like that ?
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Thanks to all for your input that was a very interesting topic
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Yes, this is an 8 year old thread, but it is also an excellent, informative thread on TAN and TBN that deserves to be resurrected.
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