dnewton3
Staff member
Originally Posted By: Gabe
Originally Posted By: dnewton3
Acids: typically only a concern when TBN is low (below 1.0) AND TAN is high (8.0-10.0 is the upper limit according to Blackstone in their testing methods).
You are probably wrong on that. HERE and HERE are a couple good articles that disagree with you.
I disagree with your assessment, and I'll speak directly to your sources.
First, the link to our site references Ryan at Blackstone; I've worked with him in some detail for my two articles. We've discussed this before between the two of us. Additionally, Blackstone is the service I use, and have been given the direct information that until TAN is high, acid is not of great concern. With their testing methods, a TAN of 8+ is considered "high".
As for the Noria link, which references Polaris labs, I've spoken with Polaris also. There is no "hard and fast" condemnation point for acid from them. The "reccommend" when TAN crosses TAN only because it is easily defined; it is NOT an assurance of things gone wrong. And how helpful is this method when you don't even know TAN? Most people only get TBN. What if TBN were 5.0, but TAN were 5.3? If you don't pay for BOTH TBN and TAN, then it could be possible for TAN to cross TBN, and you'd not know it. But for those who typically get only the TBN, they would "presume" everything is fine because the TBN was "high enough" in their mind. This is a silly way of determining an OCI if this is your SOLE condemnation method. Two lines intersect, and suddenly you presume the lube is worthless? Preposterous.
And this UOA, along with my recent UOA, are total proof of concept. Acid is only a concern if it acts upon something, right? If acid had no effect, then what would the danger be? So, the concern with low TBN and high TAN is that acid will start to eat at the metal surfaces, causing excessive wear (most specifically pitting). But I ask you, where it the evidence that the acid pitting is happening in this UOA? The Al, Cr, Pb and Cu are all flat-lined; there is not pitting occuring. The Fe wear rate is DROPPING, not climbing.
The TAN in this UOA is 3+; Blackstone warns of acid at 8+. There is life left despite what you think. Now, the question does become "how much lube life is left". That is of some debate; I agree there. And the only way to safetly asnwer that is to cautiously extend, a few thousand miles at a time, and keep a close eye on not just TAN, but wear metals.
To make an analogy, this would be akin to discussing the concern of allergens in my home. Perhaps the filter is not doing it's job of pulling out pollen, but the level of pollen has not risen enough to trigger my reaction.
Until you see wear metals react to the acid, the acid level is only cautionary, and not compulsory for a change. And it's not like a little acid will simply ruin a bearing in three minutes, either ... It takes time for such pitting to occur. Time that would easily allow for the detection of the onset.
Futher, we cannot look at singular numbers and simply forget about statistical variance. There is always some shift in each measureable. TAN actually went DOWN even though the OCI went up! Is that a correlation or causation? Is that within sigma variance or is it abnormal.
No - I do not accept the plea that acid is at a danger level here, nor was the OCI over-run. The articles you linked speak to cautionary points of awareness, not assurance of damage. They offer limits based upon general warnings, not individual assessment.
Originally Posted By: Gabe
This oil was left in too long. I am curious why we are not seeing the additional wear.
Simple - the acid is still not high enough to degrade the metals. Just because it intersected the TBN on a graph, does NOT assure an untimely death to the equipment.
Those graphs are no more useful than is a " ... or one year" OCI. They don't rely on individual assessment with wear correlation or causation; they are blind obedience traits.
In short, what does it matter if TAN is 3, 13 or 30, if wear metals are not being affected? TAN is an input measurable; wear metals are output measurables.
And that's what most folks simply don't get. They are overly concerned about inputs, and not outputs. There is plenty of proof that vis is NOT the end-all-be-all of wear control, but folks still swear by it. There are pleny of those who pledge alegience to ZDDP, but there are lots of engines that run without any of it (aircraft engines run with no ZDDP whatsoever). TAN is simply a predictor of possible future issues; it is NOT a reason to condemn a fluid solely on its merit. It is a cautionary marker, not a limit.
I don't care if a 50/50 mix of goat milk and pool cleaner was used in this engine; when wear is this good, with no contaminant intrusion, there is no reason not to continue a load.
Not to steal any thunder from Glen's UOA here (it's marvelous), but I wonder what horrid things will happen to my wife's van when I run 15k miles on ST dino, have TAN cross TBN, and still get excellent wear results? Will it still be your position that the OCI was too long?
Originally Posted By: dnewton3
Acids: typically only a concern when TBN is low (below 1.0) AND TAN is high (8.0-10.0 is the upper limit according to Blackstone in their testing methods).
You are probably wrong on that. HERE and HERE are a couple good articles that disagree with you.
I disagree with your assessment, and I'll speak directly to your sources.
First, the link to our site references Ryan at Blackstone; I've worked with him in some detail for my two articles. We've discussed this before between the two of us. Additionally, Blackstone is the service I use, and have been given the direct information that until TAN is high, acid is not of great concern. With their testing methods, a TAN of 8+ is considered "high".
As for the Noria link, which references Polaris labs, I've spoken with Polaris also. There is no "hard and fast" condemnation point for acid from them. The "reccommend" when TAN crosses TAN only because it is easily defined; it is NOT an assurance of things gone wrong. And how helpful is this method when you don't even know TAN? Most people only get TBN. What if TBN were 5.0, but TAN were 5.3? If you don't pay for BOTH TBN and TAN, then it could be possible for TAN to cross TBN, and you'd not know it. But for those who typically get only the TBN, they would "presume" everything is fine because the TBN was "high enough" in their mind. This is a silly way of determining an OCI if this is your SOLE condemnation method. Two lines intersect, and suddenly you presume the lube is worthless? Preposterous.
And this UOA, along with my recent UOA, are total proof of concept. Acid is only a concern if it acts upon something, right? If acid had no effect, then what would the danger be? So, the concern with low TBN and high TAN is that acid will start to eat at the metal surfaces, causing excessive wear (most specifically pitting). But I ask you, where it the evidence that the acid pitting is happening in this UOA? The Al, Cr, Pb and Cu are all flat-lined; there is not pitting occuring. The Fe wear rate is DROPPING, not climbing.
The TAN in this UOA is 3+; Blackstone warns of acid at 8+. There is life left despite what you think. Now, the question does become "how much lube life is left". That is of some debate; I agree there. And the only way to safetly asnwer that is to cautiously extend, a few thousand miles at a time, and keep a close eye on not just TAN, but wear metals.
To make an analogy, this would be akin to discussing the concern of allergens in my home. Perhaps the filter is not doing it's job of pulling out pollen, but the level of pollen has not risen enough to trigger my reaction.
Until you see wear metals react to the acid, the acid level is only cautionary, and not compulsory for a change. And it's not like a little acid will simply ruin a bearing in three minutes, either ... It takes time for such pitting to occur. Time that would easily allow for the detection of the onset.
Futher, we cannot look at singular numbers and simply forget about statistical variance. There is always some shift in each measureable. TAN actually went DOWN even though the OCI went up! Is that a correlation or causation? Is that within sigma variance or is it abnormal.
No - I do not accept the plea that acid is at a danger level here, nor was the OCI over-run. The articles you linked speak to cautionary points of awareness, not assurance of damage. They offer limits based upon general warnings, not individual assessment.
Originally Posted By: Gabe
This oil was left in too long. I am curious why we are not seeing the additional wear.
Simple - the acid is still not high enough to degrade the metals. Just because it intersected the TBN on a graph, does NOT assure an untimely death to the equipment.
Those graphs are no more useful than is a " ... or one year" OCI. They don't rely on individual assessment with wear correlation or causation; they are blind obedience traits.
In short, what does it matter if TAN is 3, 13 or 30, if wear metals are not being affected? TAN is an input measurable; wear metals are output measurables.
And that's what most folks simply don't get. They are overly concerned about inputs, and not outputs. There is plenty of proof that vis is NOT the end-all-be-all of wear control, but folks still swear by it. There are pleny of those who pledge alegience to ZDDP, but there are lots of engines that run without any of it (aircraft engines run with no ZDDP whatsoever). TAN is simply a predictor of possible future issues; it is NOT a reason to condemn a fluid solely on its merit. It is a cautionary marker, not a limit.
I don't care if a 50/50 mix of goat milk and pool cleaner was used in this engine; when wear is this good, with no contaminant intrusion, there is no reason not to continue a load.
Not to steal any thunder from Glen's UOA here (it's marvelous), but I wonder what horrid things will happen to my wife's van when I run 15k miles on ST dino, have TAN cross TBN, and still get excellent wear results? Will it still be your position that the OCI was too long?
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