TBN and TAN in ester oils, excellent info!

[saaber1]

I wanted to pass along a post by TomNJ regarding TAN and TBN that was really enlightening to me and may help others understand esters better.

Background:

In the past I had a redline UOA with both high TAN and high TBN and I have been really struggling to figure out how that could be. Normally I think of TBN as the buffering capacity of the oil and as TBN goes down TAN goes up. Typically we use the point when TAN = TBN as a condemnation point for oil. But a few facts had me questioning whether this "rule of thumb" applied to some of the more exotic ester-containing oils:

1) Terry Dyson's past statement about how a BStone TBN level of 0 was acceptable for redline
2) The redline oils start at about TAN of 2.5 rather than somewhere near 0
3) The UOA that showed both TAN and TBN to be high at the same time
4) Renewable lubricants Biosyn often shows decreasing TAN in a UOA vs. VOA Which is the opposite of what we would expect.
I asked Tom if the same TAN=TBN rules should apply to ester oils and his post here really shed light on this issue for me! Thanks TOM!!!

Originally Posted By: Tom NJ
There probably should be a different set of rules for ester based motor oils. Pure synthetic ester base oils have a zero TAN and TBN, so the higher TAN in the formulated products must come from additives. Bio-based base oils may have a slight TAN (
Esters, whether synthetic or bio-based, are constructed from acids and alcohols, and are subject to hydrolysis (reaction with water). Unlike with hydrocarbon base oils, hydrolysis breaks the ester back to acids and alcohols, so a rise in TAN is more likely with esters than hydrocarbons. The acids liberated, however, are weak organic fatty acids and do not do damage unless present in high doses. This is why a high TBN can coexist with a high TAN in such oils. Indeed some of these fatty acids act as corrosion inhibitors! The acids liberated from the degradation of hydrocarbon base oils, however, are much stronger and corrosive. Hence I would expect a different set of rules for ester based oils to allow more TAN than with hydrocarbon based oils.

There are different TAN rules for esters in other industries. In monitoring air compressor oils, for example, a TAN of only 0.2 is concerning for mineral oil formulations, while I have seen recommendations from some manufacturers allowing as high as 5 to 8 TAN before changing for ester oils.

Without field data to the contrary, I would tend to ignore TANs in high ester based motor oils so long as other UOA data is normal.

Tom

 

[StevieC]

Thanks for posting... Maybe now we can put the "Biosyn is bad" to rest...

 

[saaber1]

Originally Posted By: StevieC
Thanks for posting... Maybe now we can put the "Biosyn is bad" to rest...


I would say it is one more important piece of knowledge to have when trying to interpret a UOA only. All the other elements of the UOA should of course be looked at as well but it does help us to understand those odd (compared to non-ester) TBN/TAN levels, especially as it applies to condemnation points.

 

[StevieC]

Granted... I was just trying to point out that there are a lot of members on here who put down Redline and RLI Bio-Syn because of high TAN readings... When they might in most cases be fine and be as a result of the information posted above.

Apparently, Terry Dyson has lost a lot of creditability here with some members because they think that higher TAN numbers in RLI samples, both V&U, are bad and causing harm to the engine when in fact they arent. This most likely makes Terry right all along.

I trust Terry and think he is a very scientific knowledgeable guy and completely trust him with my vehicles maintenance regiments.

Perhaps with this information those same people can learn to realize that he isn't out to lunch as they think he is for sugguesting the use of RLI oils which in most cases are superior to anything I have ever tried...

Also, not to sound like a salesman or a spokesperson for Terry, but they are also made from a renewable resource which in my books is always better than war based oil supplies. Lets not go there though... As it is political and banned from this board.

Just some food for thought though...

 

[saaber1]

It also brings up an interesting question, "How do we determine the condemnation point from a UOA for these oils?"

I agree the knowledge of guys like Terry Dyson and TomNJ are invaluable when we talk about ester oils. I feel like I know so little when reading posts like Tom's or Molakule's for example.

.

 

[StevieC]

I think the average person really can't read a UOA and make a judgment call for themselves in most cases. On contamination issues yes but otherwise I think it takes a skilled professional like a lab tech's comments or someone like Terry to make the call.

These people see infinite samples and see averages/trends and call based on experience IMO.

While a lot of people on here want to think they can call things based on UOA's the simple truth is most can't unless it's blatantly obvious like fuel dilution, insoluble, Water/Glycol contamination. or TAN/TBN numbers that are way out of the norm.

Look at how many people run M1 products even with higher than average Iron numbers and don't see a problem and are able to get more miles out of an engine than they wanted with documented tear down picture proof showing spotless internals and almost immeasurable wear, yet we have others that steer clear of M1 because they think they are experts and that high Iron in a UOA means the engine is wearing excessively.

 

[Pablo]

Originally Posted By: Tom NJ


Esters, whether synthetic or bio-based, are constructed from acids and alcohols, and are subject to hydrolysis (reaction with water). Unlike with hydrocarbon base oils, hydrolysis breaks the ester back to acids and alcohols, so a rise in TAN is more likely with esters than hydrocarbons. The acids liberated, however, are weak organic fatty acids and do not do damage unless present in high doses.


Some weak organic acids are very good chelating agents. This could help explain the relatively higher metals in solution in some UOA's.

 

[StevieC]

Pab's from what I understand, and again, not to sound like a salesman/spokesperson... But doesn't the higher metals in the UOA normalize after a few runs of an Ester based oil because it's just cleaning up wear metal residue that other oils seem to leave behind?

Once these are gone the numbers fall into line like other oils correct?

 

[Doug Hillary]

Hi,
saaber1 - IMHO the Manufacturer's TBN UOA condemnation point would still be applicable. Remember that they test and Approve many lubricant types inclouding those with a significant ester content

It would be a bold soul you would run any lubricant with a TBN below 1 (D4739)

In diesel engines where the TAN is quite a meaningful analysis item very few engine Manufacturers quote a condemnation number. I always used both on my trend database and used their "balance" as the main item. I often found the TBN to be incorrect when compared to the TAN. At no time over many many millions of kms was either a high TAN or a depleted TBN been the lubricant's condemnation point. My average TAN at OCI (90kkms) was 7 and TBN 2

In petrol engines using the same lubricant with a starting TBN of 11 and with a significant ester content, my highest TAN has been 4.6 and TBN 8.10 - at 19kkms

I hope this adds something

 

[StevieC]

Doug,

Please enlighten us some more regarding Ester oils. I for one, respect your views, opinions and posts.

So let us have it regarding ester oils...

 

[Pablo]

Originally Posted By: StevieC
Pab's from what I understand, and again, not to sound like a salesman/spokesperson... But doesn't the higher metals in the UOA normalize after a few runs of an Ester based oil because it's just cleaning up wear metal residue that other oils seem to leave behind?

Once these are gone the numbers fall into line like other oils correct?


Yes. That is what I'm saying in relation to "cleaning up"....any "loose" metals are chelated and put into solution.

 

[StevieC]

That's what I thought... Just wanted to make sure. Figured you were a knowledgeable guy!

 

[OVERKILL]

Great thread!

I think this again, like with many other posts on UOA's goes to simply extend the view (as StevieC pointed out) that UOA's REALLY are not as useful as many want them to be... especially for the average person.

I am not saying they are without value; for that is clearly not the case. It just seems that many want to see what they cannot really see, and draw conclusions based on data that they really do not understand enough to actually draw those conclusions.

Again, this appears that working in concert with somebody who is knowledgeable and experienced in this subject is the best method in getting the most value out of the data.

 

[Doug Hillary]

Hi,
StevieC - This subject is very complex and a truely meaningful all encapsulating answer is probably not possibe here. And I am no expert on the subject!

saaber1 said this:

"Typically we use the point when TAN = TBN as a condemnation point for oil.

I have never seen this as a condemnation point but obviously others have. Maybe correctly so too!

I believe too that depending on the formulation some ester containing lubricants may well distort a UOA or two until they have stabilised with the remants of the old lubricant and its "residue"

Now my "two bobs" worth........

Esters
For one thing there is a plethora of "esters" from various sources. They are really the product of the reaction of alcohols and acids. Esters as a lubricant component were Patented in the late 1800s as I recall. German Chemists and Engineers investigated and researched this area during the period from around 1935 and especially from around 1940 until the end of WW2

Data from this period was used by the major Oil Companies after the end of hostilities - many had functional Entities operating within Germany during the 1930s

German esterification experience (in a nutshell)
The Germans found that esters as/in lubricants had some desirable and some undesirable features. Undesirable was the level of insability of some and poor lubricating charteristics of others - and etc. In the end they settle for di-esters (two ester groups) seperated by a staright chain of carbon atoms. They used beta-methyl adiptic acid instead of adiptic acid and produced lubricants with pour points down to -33C. These had excellent oxidation stability and lubrication charcateristics. Shortages of acids and alchols inhibited development and production capacity. So here we have the foundation of modern esters!

Modern ester production and use in lubricants is well handled IMO by the major Oil and Chemical Companies. They can spend the huge amounts of money on research and development

As specialised engine lubricant suppliers Burmah Oil (Castrol) was an early pioneer with their castor bean oil based products being the benchmark for race engines for decades. They are still available today of course

Castrrol "R" 30 & 40
My own experience with Castrol's ester based lubricants commenced around 1952 when my family used Castrol "R" castror based lubricants in our racing motorcycles - Nortons, Triumphs,BSAs and Matchless/AJSs. Oil was changed after each race using a mineral oil and kerosine flush due to the actions of the lubricant. This included various engine deposits including ring sticking and etc.

Formula R 15W-50 (around 1979)
This was a di-ester caster based, red wine coloured lubricant with the typically lovely exhaust odour. It was stressed never to exceed the Manuafcturerer's OCI! I worked with this lubricant until its first rehash around 1981 and then thereafter in field trials over several years

The new formulation was PAO based as I recall with a di-ester component. This is what is now known as the BMW 10W-60 lubricant. It and its Castrol cousin Edge Formula RS 10W-60 are the "viscous" lubricants of choice used by racers in Germany today! RS 10W-60 has a long chain Alkylsalicylat and calcium salt components of about 5%

Typically the early castor based 15W-50 version of this lubricant became more viscous with use and was prone to engine (not combustion) deposits. It required using the OCIs of the day typically around 3kkms. It was not a popular product except amongst enthusiasts

The later versions were much more user friendly. I used this new formulation in a wide variety of engine configurations, both petrol and diesel and reached OCIs of 3500hrs (around 280kkms - 174k miles) in light Japanese diesel engines! I used this lubricant as my general service product in many diverse engine families until around 1996!

Castrol Formula SLX 0W-30 (known as GC)
This SH/CF lubricant was introduced into Australia shortly after is was released in Germany in 1996. I commenced using it immediately as I was already involved in Field Testing Castrol's semi synthetic HDEO (Enduro LD). The SLX lubricant had a low phosphorous and low chlorine di-ester formulation and had VW500-505 and Porsche approvals. It was ACEA A3-96/B3-96 "certified" and one of ACEA's first Approvals!
It survived well in my BMW R100RS bike and in a number of Japanese engines - and in a 4ltr Explorer.
It caused a a component failure in 2ltr VW engine that called for the 500-505 specification. This vehicle normally had very high oil temperatures (120C-130C) and an oil tep gauge and light!
My engine failure related to engine deposits and the seizing up of the OP drive shaft
VW and MB stopped using the product shortly after!
The lubricant was later sourced from Singapore, had many forumlation changes and was
withdrawn from sale here around 2001

Today Castrol Edge Formula RS 0W-40 has a long chain Alkylsalicylat and calcium salt components of about 5% - just like RS 10W-60

Gear Oils
I have estensive exposure to some applications where vegetable based lubricanst performed very well. Some were the excellent products from Shell. Even Porsche at one point specified a "whale oil" based lubricant for use in their MB sourced autotransmissions

I am still a little wary of "new" "ester products from small organisations that do not have the field testing facilities of the major Oil Companies. Their field testing platfom is usually estensive enough to cover many vehicle types and many applications - and they can accumulate data fast

So IMO modern high priced lubricants using PAOs and/or esters are truely magical lubricants in the correct environment

As to engine lubricants a retired MB Director with a responsibility for lubricant supply and quality said to me recently - "I never saw enything that convinced me that high proced synthetic performed better in our cars than any of the others on our Approval List"

Many race car engineers I spoke with at the Nurburgring in May said this (in a variety of ways) "All modern lubricants perform about the same - the correct viscosity is really the most important thing"

I agree with their remarks!

 

[azsynthetic]

MB's Aprroval list is not exactly a list of cheap oils.

 

[StevieC]

Originally Posted By: azsynthetic
MB's Aprroval list is not exactly a list of cheap oils.
Doesn't have to be... If you can afford the car you should be able to afford its maintenance regiment.

 

[saaber1]

Doug, great info. as always. I know that general rule of thumb of TAN=TBN is used by quite a few people f.e.
Originally Posted By: bruce381
My rule of thumb is when TBN drops close to TAN change it...

but perhaps it has limited applicability? It looks to me that for esters anyway that rule probably shouldn't be used.

I respect what you are saying about the manufacturers recommended condemnation points, but I think those have limited applicability as well.

Originally Posted By: Doug Hillary
...
Engine manufacturers set their own condemnation limits concerning viscosity when using UOAs (in use).

A typical criteria states:

Viscosity @ 40C cSt
% Max Increase - 40%
% Max Decrease - 15%
...


F.e. if we apply the "15% decrease" to mobil 0W40 on some engines where it quickly shears down more than 15% as documented on numerous UOAs found here on BITOG and other testing such as from Dyson:

Originally Posted By: Terry
... reb03, I have customers running BMW5w30, M1 0w40 all with the same effect, the wear control is good if we change the oil at 1000 mile intervals but the deposit formation from REAL volatility issues are slowly damaging the engines. I just worked a 07 335 Biturbo yesterday USING ASTM lab tests on the used oil and M1 0w40 went from VOA flash of 430+F to 280 F in 1150 miles, oil sheared to 12.1 cSt and fuel was at 1.99% by IR. Amsoil has not been tested in this engine yet. Because Amsoil is a traditional based PAO I predict similar results to the M1 0w40 which is still one of few M1 products that can perform reasonably well....Terry

It Doesn't seem like that 15% drop in viscosity rule of thumb applies to M1 0W40 otherwise we'd have to change it out at very low miles on some engines such as shown above.

What I am getting from this discussion so far is that "rules of thumb" for condemnation points can have limited applicability and the whole picture (iron levels, viscosity, TBN, TAN, fuel, etc.) should be used to determine the condemnation point. As Stevie said, this is where folks like Dyson can be of real help when looking at individual UOAs.

 

[azsynthetic]

Originally Posted By: StevieC
Originally Posted By: azsynthetic
MB's Aprroval list is not exactly a list of cheap oils.
Doesn't have to be... If you can afford the car you should be able to afford its maintenance regiment.

You missed my point. I was preferring to this:

"As to engine lubricants a retired MB Director with a responsibility for lubricant supply and quality said to me recently - "I never saw enything that convinced me that high priced synthetic performed better in our cars than any of the others on our Approval List"

The oils on MB list are already high priced synthetic.

 

[StevieC]

No I got your point... I was making a sarcastic remark. Not towards you, but in general.

 

[element_42]

Originally Posted By: Doug Hillary


Castrol Formula SLX 0W-30 (known as GC)
This SH/CF lubricant was introduced into Australia shortly after is was released in Germany in 1996. I commenced using it immediately as I was already involved in Field Testing Castrol's semi synthetic HDEO (Enduro LD). The SLX lubricant had a low phosphorous and low chlorine di-ester formulation and had VW500-505 and Porsche approvals. It was ACEA A3-96/B3-96 "certified" and one of ACEA's first Approvals!
It survived well in my BMW R100RS bike and in a number of Japanese engines - and in a 4ltr Explorer.
It caused a a component failure in 2ltr VW engine that called for the 500-505 specification. This vehicle normally had very high oil temperatures (120C-130C) and an oil tep gauge and light!
My engine failure related to engine deposits and the seizing up of the OP drive shaft
VW and MB stopped using the product shortly after!
The lubricant was later sourced from Singapore, had many forumlation changes and was
withdrawn from sale here around 2001



Yeh?? Wow!

Quote:

I am still a little wary of "new" "ester products from small organisations that do not have the field testing facilities of the major Oil Companies. Their field testing platfom is usually estensive enough to cover many vehicle types and many applications - and they can accumulate data fast



Interesting note, Mr Hillary

Thank you for the information!