Importance of keeping TBN High

[paulri]

Originally Posted By: Ducked
That graph has some features I've never understood.

What's the X-axis, and how do they get away with publishing a graph without it labelled (assuming they have editors who know their arse from their elbow)?

I'd guess OCI (time) would make sense. A plot of TBN against TAN would too.

Why that clear "wedge" under the TBN line, the bit with no TAN points? (The TBN line is perhaps "theoretical". There's no way that's real raw data, though I suppose it COULD be a fitted curve).


I think I'll send an email to the organization that was listed as the author for that article.

The x (horizontal) axis could be time, or miles after the most recent oil change. On the other hand, it might not refer to anything at all. The "real raw data" would be the blue dots, which represent a reading from a truck's TAN. The higher the TAN, the higher up (y axis) that dot is placed. But what determines the x axis is simply what the TBN is at the time of the reading. I read that chart as, "When TBN is this much, TAN is that much." The TBN line might simply be portrayed to look like a typical TBN trajectory in an individual vehicle.

 

[HerrStig]

Time to add a PH meter to the OLM sensors? Or, perhaps that's all that's needed.

 

[Ducked]

Originally Posted By: HerrStig
Time to add a PH meter to the OLM sensors? Or, perhaps that's all that's needed.


Good trick if you can do it.

Direct measurement of pH in oil with a sensor robust enough to stand operating engine conditions is quite a technical challenge. The lab methods use a bridging solvent to make a proxy measurement with the oil in an aqueous medium.

 

[Ducked]

Originally Posted By: paulri
Originally Posted By: Ducked
That graph has some features I've never understood.

What's the X-axis, and how do they get away with publishing a graph without it labelled (assuming they have editors who know their arse from their elbow)?

I'd guess OCI (time) would make sense. A plot of TBN against TAN would too.

Why that clear "wedge" under the TBN line, the bit with no TAN points? (The TBN line is perhaps "theoretical". There's no way that's real raw data, though I suppose it COULD be a fitted curve).




I think I'll send an email to the organization that was listed as the author for that article.

The x (horizontal) axis could be time, or miles after the most recent oil change. On the other hand, it might not refer to anything at all. The "real raw data" would be the blue dots, which represent a reading from a truck's TAN. The higher the TAN, the higher up (y axis) that dot is placed. But what determines the x axis is simply what the TBN is at the time of the reading. I read that chart as, "When TBN is this much, TAN is that much." The TBN line might simply be portrayed to look like a typical TBN trajectory in an individual vehicle.


Think that's what I said, except, if its a TAN/TBN plot, the X-axis refers to TBN, not "it might not refer to anything at all".

How about that clear "wedge"?

IF its a TAN/TBN plot (Whether or not the TBN line is just theoretical/fictitious "decoration") it implies a discontinuity in the TAN/TBN relationship, so TAN "jumps" within a certain range of TBN values, and some intermediate TAN values just don't happen for that range of TBN values.

Can't offhand think of an explanation for that, yet, IIRC, there's no comment on it in the article.

 

[bobbydavro]

TAN above 6-7 is when to start getting concerned.

 

[A_Harman]

Originally Posted By: Nyogtha
No buffered solutions have a linear titration (depletion) curve.

They go very slowly until most of the buffer has been consumed / neutralized, then drop sharply.

What you don't want to do is run out of (in this case) base. You want to dump before you go beyond the equivalence point, so in this case you dump before you reach the equivalence point, while the solution is still alkaline.

How close is too close? That's an individual judgement.

PQIA suggests dump if TBN < 3.

http://www.pqiamerica.com/TBN.htm

A set of UOA data certainly can be used to get closer.


I have been using Polaris labs for my UOA's, and their recommendation is to change oil when TBN gets to 35% of virgin. This agrees pretty well with what the PQIA is saying for most oils. (TBN 8-10)

But when I worked at Cummins, they had a different rule than that. It seems there is no universal answer.