dnewton3
Staff member
I disagree.
THE MAIN JOB OF OIL IS TO REDUCE WEAR. That's it. Sure, oil additives do things like clean, and oil is used as a cooling medium, but the MAIN job is to control wear. So .... wear is what we care about. Or more specifically, we want little wear; the less, the better. Most specifically, we want low wear rates.
TBN and TAN are not things that control wear. They are inputs to the oil equation. The output is wear data; how much metal is the engine shedding in normal operation?
We have seen countless examples where TBN is low and wear rates continue to drop.
We have seen countless examples where TAN crosses over TBN and wear rates continue to drop.
We have seen countless examples where FP is low and wear rates continue to drop.
We have seen countless examples where Vis is out of grade and wear rates continue to drop.
We have also seen countless examples where those inputs were totally fine, and wear was abnormal.
Now I'm going to remind you all of a very fundemental, yet totally inescapable, fact ...
Without correlation, there can be no causation.
Meaning if TBN dropped and wear wasn't negatively affected, then TBN is moot at that point in time.
Meaning if TAN usurps TBN and wear wasn't negatively affected, then crossover is moot at that point in time.
Meaning if Vis is out of grade .... (you get the picture) ...
It is very important to track things like Vis, FP, TBN/TAN and others because they are inputs to an equation. When those inputs change, they may trigger a change in outputs. Not "will trigger", but "may trigger'. When those unputs go out of "normal" bounds, it's a reason to watch the outputs (wear metals) ever closer because things might change.
When TAN crosses TBN, it's not an assurance that wear is automatically going to explode into some exponential slope of doom; it's merely a reason to perhaps UOA more often such that you can look for the trend shift in wear metals indicating that non-normal is approaching on the horizon.
I would argue this ... the FIRST thing to look at in a UOA is the wear rates. If they are "normal", then stop reading. If wear is "normal" and trending in a desirable direction, the rest is just hokum that will distract you from the MAIN goal of any lube - that of holding wear back. The ONLY reason to look at the inputs is to see if the next UOA may be needed a bit sooner, but ONLY if the inputs are not as exepected. That's not a reason to OCI or panic; merely a reason to UOA a bit sooner the next time.
NOTE: (I will admit that using the UOA to look for contamination suspected is also a good reason to look at UOAs; fuel, silica, coolant all can ruin your day and your engine if not tracked, but those are mechanical issues and not "oil" issues. If you suspect a leak at the injectors, the air filter, the head gasket, then by all means use that data to make your decision irrespective of the wear.)
In this UOA, the vis is up a tad; so what? Didn't hurt wear rates.
In this UOA, the FP is a tad low; so what? Didn't hurt wear rates.
In fact, the Fe wear continued to drop, and the rest of the metals are so low they're just noise.
The contaminaiton is decent; insolubles low and coolant nil. Perhaps keep an eye on the Si closely; it jumped up.
The BS recommendation to UOA the next time at 21k miles is totally rational and reasonable. No TBN/TAN required.
There's nothing wrong with these results and the ONLY takeaway is that he needs to continue to monitor the OCIs closely because he's treading out far enough that data is thin from macro sourcing; he's bolding going where few have gone before.
THE MAIN JOB OF OIL IS TO REDUCE WEAR. That's it. Sure, oil additives do things like clean, and oil is used as a cooling medium, but the MAIN job is to control wear. So .... wear is what we care about. Or more specifically, we want little wear; the less, the better. Most specifically, we want low wear rates.
TBN and TAN are not things that control wear. They are inputs to the oil equation. The output is wear data; how much metal is the engine shedding in normal operation?
We have seen countless examples where TBN is low and wear rates continue to drop.
We have seen countless examples where TAN crosses over TBN and wear rates continue to drop.
We have seen countless examples where FP is low and wear rates continue to drop.
We have seen countless examples where Vis is out of grade and wear rates continue to drop.
We have also seen countless examples where those inputs were totally fine, and wear was abnormal.
Now I'm going to remind you all of a very fundemental, yet totally inescapable, fact ...
Without correlation, there can be no causation.
Meaning if TBN dropped and wear wasn't negatively affected, then TBN is moot at that point in time.
Meaning if TAN usurps TBN and wear wasn't negatively affected, then crossover is moot at that point in time.
Meaning if Vis is out of grade .... (you get the picture) ...
It is very important to track things like Vis, FP, TBN/TAN and others because they are inputs to an equation. When those inputs change, they may trigger a change in outputs. Not "will trigger", but "may trigger'. When those unputs go out of "normal" bounds, it's a reason to watch the outputs (wear metals) ever closer because things might change.
When TAN crosses TBN, it's not an assurance that wear is automatically going to explode into some exponential slope of doom; it's merely a reason to perhaps UOA more often such that you can look for the trend shift in wear metals indicating that non-normal is approaching on the horizon.
I would argue this ... the FIRST thing to look at in a UOA is the wear rates. If they are "normal", then stop reading. If wear is "normal" and trending in a desirable direction, the rest is just hokum that will distract you from the MAIN goal of any lube - that of holding wear back. The ONLY reason to look at the inputs is to see if the next UOA may be needed a bit sooner, but ONLY if the inputs are not as exepected. That's not a reason to OCI or panic; merely a reason to UOA a bit sooner the next time.
NOTE: (I will admit that using the UOA to look for contamination suspected is also a good reason to look at UOAs; fuel, silica, coolant all can ruin your day and your engine if not tracked, but those are mechanical issues and not "oil" issues. If you suspect a leak at the injectors, the air filter, the head gasket, then by all means use that data to make your decision irrespective of the wear.)
In this UOA, the vis is up a tad; so what? Didn't hurt wear rates.
In this UOA, the FP is a tad low; so what? Didn't hurt wear rates.
In fact, the Fe wear continued to drop, and the rest of the metals are so low they're just noise.
The contaminaiton is decent; insolubles low and coolant nil. Perhaps keep an eye on the Si closely; it jumped up.
The BS recommendation to UOA the next time at 21k miles is totally rational and reasonable. No TBN/TAN required.
There's nothing wrong with these results and the ONLY takeaway is that he needs to continue to monitor the OCIs closely because he's treading out far enough that data is thin from macro sourcing; he's bolding going where few have gone before.
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