TBN Question???

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I see the data from UOAs and understand the comparison of results to universal averages down the list, but when I see the TBN reading listed at the bottom of a Blackstone report, what is the quantitative date relating to in comparison? A reading of the additives left compared to a Virgin Oil Analysis sample of the same exact oil being tested?

Every oil has a different amount of additives, but listing a number, let's say 1.2, in the TBN results, what exactly does that compare to and where does the data translating this to a recommended OCI (longer or shorter interval) come to be.

In other words, how is the TBN data translated into a measurement of OCI length. I hope my query is understood.

Thanks for any help, and if this has been discussed please feel free to post a link to thread.

-Scott
 
I can't answer but first part of your question but can offer an opinion for the second part.

I think most people would agree that the higher the TBN of an oil, the longer the oil might potentially last in terms of OCI. However in my experience, it's nigh on impossible to quantify how much 'extra' OCI you get for an 'extra' boost of TBN because the life of the oil depends on so many other factors.

In fact, I'd go so far to say that even if you know every last single thing about an oil, how and where it will be driven and in what specific vehicle, there is no way of saying what the maximum life of that oil would be. One of my biggest criticisms of the way oils are now approved to API & ACEA set specifications, is that the engine tests are now so horribly mutated that they no longer bear any resemblance to real-life driving conditions. It therefore should come as no surprise that the tests effectively tell you naff all about the one thing that the average bloke in the street cares about which is his long the oil will last.
 
I don't know if this answers your question and I may be telling you something you already know so, no insult is intended.

Most virgin oils start out with a neutral pH of 7 or higher(typically, water is neutral at a pH of 7). So, most oils(mostly conventional oils) start out ~ 7.

As the oil in the engine becomes more acidic(due to combustion byproducts), the pH drops. Base, raises ph and Acid lowers pH. Hence, TBN/total base number & TAN/total acid number.

Over time, acid attacks the aluminium with a pH lower than 2(from my understanding), which is a concern.

Base is the opposite of Acid. When I worked in MFG'ing, and we needed to lower a pH of a chemical, we added acid. And when we needed to raise the pH of a chemical, we added base.

Is this ^^^ what you were asking?
Hope this helped!
 
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Originally Posted By: sundaytrucka

In other words, how is the TBN data translated into a measurement of OCI length. I hope my query is understood.



I don 't think it is translated into an OCI, or could be, since the rate of depletion will depend on the engine and the conditions of service.

There are "rules of thumb" as to what level of depletion signals the need for an oil change, and the relationship between TBN (goes down) and TAN (goes up) is sometimes considered too.

This article “Optimizing Drain Intervals Using TBN vs. TAN

http://www.machinerylubrication.com/Read/2170/oil-drain-interval-tan-tbn

suggests 65% depletion as a change point. It shows a graph depicting the relationship between TBN and TAN. It has some puzzling features (that “clear wedge” with no TAN points, for example) and apparently the authors never been told to label his X-axis, (tsk tsk!) but the basic inverse relationship is pretty much what you’d expect.
 
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Originally Posted By: Char Baby
I don't know if this answers your question and I may be telling you something you already know so, no insult is intended.

Most virgin oils start out with a neutral pH of 7 or higher(typically, water is neutral at a pH of 7). So, most oils(mostly conventional oils) start out ~ 7.

As the oil in the engine becomes more acidic(due to combustion byproducts), the pH drops. Base, raises ph and Acid lowers pH. Hence, TBN/total base number & TAN/total acid number.

Over time, acid attacks the aluminium with a pH lower than 2(from my understanding), which is a concern.

Base is the opposite of Acid. When I worked in MFG'ing, and we needed to lower a pH of a chemical, we added acid. And when we needed to raise the pH of a chemical, we added base.

Is this ^^^ what you were asking?
Hope this helped!


TBN pertains to the ability for the oil to deal with acids produced by combustion. But TBN is not pH. So do not confuse the two. Some high quality oils are above 10, close to 12. The depletion is not linear. Also the various labs will have a slight variation in TBN.

I would prefer for it to not go below 2.
 
^ Think of TBN as your "safety net" against acid corrosion in your engine-when it runs too low, & the T(otal) A(cid) N(umber) starts getting too high, the motor oil will attack the metals in the crankcase & rust will begin. Short trips, cold weather, & good old fashioned high sulfur gasoline here in the USA all accelerate TBN depletion.
 
Here's something I wrote a while ago.

Also, pH is meaningless in the context of oils, since pH is, by definition, an aqueous property (water-soluble); "pH" literally stands for "-log¹⁰[H⁺]", which is the negative logarithm (base 10) of the concentration of dissociated hydrogen ions. Since oil is non-aqueous there will be no dissociated hydrogen ions in 'solution'.
 
potential of Hydrogen. The are minute amounts of water in the oil coming from the blowby and water in the air. I use to test the aqueous solution in my catch cans for pH and it would be slightly acidic, I assume from the CO2.
 
Originally Posted By: weasley


Also, pH is meaningless in the context of oils, since pH is, by definition, an aqueous property (water-soluble); "pH" literally stands for "-log¹⁰[H⁺]", which is the negative logarithm (base 10) of the concentration of dissociated hydrogen ions. Since oil is non-aqueous there will be no dissociated hydrogen ions in 'solution'.


And yet used oil analyses routinely report % water contamination. I assume this water is present as a separate phase, perhaps a finely dispersed emulsion. It seems a fair bet that some acidic components in the oil are water soluble to some degree and will partition out into this phase.

I believe this isn't what pH measurements of oil are reporting, however, (since the pH of the oil isn't/cannot be measured directly), but then TBN and TAN aren't measured directly either.

IIRC, in all these cases, bridging solvents are used to get the components of interest into aqueous solution, where traditional "wet chemistry" titrations can be done.

The significance of pH measurements seems to be controversial and I understand they aren't an officially recognised (eg ASTMS) procedure. Here's an article on it.

http://www.machinerylubrication.com/Read/100/ph-test-tan-tbn

If I can summarise the discussion, the authors suggest that their "apparent pH" reading is dominated by strong acids (contaminants from combustion) rather than the weak carboxylic acids produced by oil oxidation, which would be picked up in a TAN titration. These strong acids correlate with observable corrosion.
 
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First off. let me say thank you to everyone for their respective responses and information. I am new to the lubrication "world", so any and all info I can get is a plus, whether it pertains to the exact topic and question or not, I genuinely appreciate the sharing of knowledge.

I gather from the responses that not one test or line result of a UOA gives you the information of how long you can go (OCI) on a given oil. The reason I initially asked the question is that I was planning on sending in a sample to Blackstone for analysis, this will be the first time I have done such a thing, and frankly felt a little weary about paying for the TBN test.

I read over the BITOG article of the process Blackstone commits to a customer's oil analyses, and found the TBN results, and the general purpose of the test to be quite dubious...They (Blackstone) represent the TBN test as a longevity monitor for oil life, but based on a real world take TBN has nothing much to do with the life of the oil without all the other data, and even then it may be unnecessary, and not to be political about it, but it is represented as a marker of how much life is left in the oil, but there is no data supplied in a UOA that directly gives you the monitor of oil life based on TBN results. From checking out member posted UOAs here on BITOG, all I have seen is some tech comments in a Blackstone UOA about running the oil longer, but no relation to TBN data as the reasoning, just general advice on the oil being capable of going longer with an OCI.

I am not trying to put down the TBN test, much less Blackstone, but I feel their representation of the TBN test is nothing more than pandering to psych $10 extra from those who care about the blood of their automobiles. I know there are other labs out in the World, so please save the comments protecting the sacred Blackstone, I am more concerned with, what I BELIEVE to be, the mass misconception or misrepresentation of a test.

Don't mean to be so analytical of a reason behind a test, but that is just how I am, and have to put it out there.

-Scott
 
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Quotes from the article about Blackstone analysis:

"TBN/TAN tests have become very popular, especially with persons wanting to validate their fluids for continued extended service."

"Stark estimates that 75% of BITOGers get TBN tested, while perhaps only 20% of the rest of their clientele get TBN tested."

No statement of how the results and data of a TBN/TAN apply to the monitoring of oil life available, or even a little more depth on the process and analytic results... To a test that cost an extra 1/3 of the standard UOA test price.

-Scott
 
Thing is, if you want an economic justification for getting an oil analysis, then you'd better be running a trucking company.

If you're a private motorist, it probably isn't cost effective.

But if its a hobby, that won't matter.
 
I 100% agree with you.

Just my overly analytical personality getting in the way of myself, I was quite excited about learning the life possibility of my oil, that, and my being frugal.

I am going to get the UOA done through Blackstone, but will pass on a TBN test.

Thank you again for the information.

And if anyone has some data to knock me off my anti-TBN high-horse, please feel free to rebuttal my concerns.

-Scott
 
Not everyone on this site uses Blackstone. I use Polaris labs, and they provide TBN in their basic charge for UOA package. And there are differing opinions on how low to allow the TBN to go. Surprise, surprise...Although I'd very must trust the article referenced from Machinery Lubrication...they're not trying to sell either motor oil or fram filters.
 
Originally Posted By: Ducked
Originally Posted By: sundaytrucka

In other words, how is the TBN data translated into a measurement of OCI length. I hope my query is understood.



I don 't think it is translated into an OCI, or could be, since the rate of depletion will depend on the engine and the conditions of service.

There are "rules of thumb" as to what level of depletion signals the need for an oil change, and the relationship between TBN (goes down) and TAN (goes up) is sometimes considered too.

This article “Optimizing Drain Intervals Using TBN vs. TAN

http://www.machinerylubrication.com/Read/2170/oil-drain-interval-tan-tbn

suggests 65% depletion as a change point. It shows a graph depicting the relationship between TBN and TAN. It has some puzzling features (that “clear wedge” with no TAN points, for example) and apparently the authors never been told to label his X-axis, (tsk tsk!) but the basic inverse relationship is pretty much what you’d expect.


That's the article I based my OCI on, although Blackstone keep saying that a TBN of greater than one is OK.

As far as I understand you will not get any significant sludge form untill all the detergents are used up and that tends to mean the TBN has dropped below 1, BUT in both cleaning and acidity level terms I stick to the one third rule which seems to be mentioned in several major studies of diesel engines. Obviously that means you do need to know the initial VOA TBN, which in the case of the oils I use is around 9, so I use 3 as a minimum.

I've talked to a few oily guru R&D types in my local lab and their opinion was that the acid level of the oil was not very significant in wear terms unless the engine was not run for long periods and that a TBN of 1 was probably OK unless the engine had a turbo, as any deposits of varnish in the oil feed pipe to the turbo could be very critical in bearing wear terms.

So my conclusion for min TBN: 1 for non turbo engines and one third of original TBN for turbo engines.
 
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Originally Posted By: UltrafanUK
Originally Posted By: Ducked
Originally Posted By: sundaytrucka

In other words, how is the TBN data translated into a measurement of OCI length. I hope my query is understood.



I don 't think it is translated into an OCI, or could be, since the rate of depletion will depend on the engine and the conditions of service.

There are "rules of thumb" as to what level of depletion signals the need for an oil change, and the relationship between TBN (goes down) and TAN (goes up) is sometimes considered too.

This article “Optimizing Drain Intervals Using TBN vs. TAN

http://www.machinerylubrication.com/Read/2170/oil-drain-interval-tan-tbn

suggests 65% depletion as a change point. It shows a graph depicting the relationship between TBN and TAN. It has some puzzling features (that “clear wedge” with no TAN points, for example) and apparently the authors never been told to label his X-axis, (tsk tsk!) but the basic inverse relationship is pretty much what you’d expect.


That's the article I based my OCI on, although Blackstone keep saying that a TBN of greater than one is OK.

As far as I understand you will not get any significant sludge form untill all the detergents are used up and that tends to mean the TBN has dropped below 1, BUT in both cleaning and acidity level terms I stick to the one third rule which seems to be mentioned in several major studies of diesel engines. Obviously that means you do need to know the initial VOA TBN, which in the case of the oils I use is around 9, so I use 3 as a minimum.

I've talked to a few oily guru R&D types in my local lab and their opinion was that the acid level of the oil was not very significant in wear terms unless the engine was not run for long periods and that a TBN of 1 was probably OK unless the engine had a turbo, as any deposits of varnish in the oil feed pipe to the turbo could be very critical in bearing wear terms.

So my conclusion for min TBN: 1 for non turbo engines and one third of original TBN for turbo engines.



Thank you for the reply!

Basing UOA TBN results on a comparison to a VOA of that same oil makes perfect sense. That was the clarification I was looking for!!!

I know it it may be trivial, but being new to this I really did not understand what the TBN was compared to...But I am learning a lot in the process.

Are there any resources of VOAs, or any labs that supply a VOA comparison of the same oil with the UOA results.

Thank you Ducked and UltrafanUK for your informative replies!!!
 
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