Originally Posted By: Gubkin
Originally Posted By: dnewton3
Your observation is flawed
Cummins, MTU and other says that you....
1.0 min limit TBN - [censored]
Typical misunderstanding of the topic.
I fully realize that some OEMs set condemnation limits. But those limits (not unlike OCI limits) are predicated on protecting their bottom line in terms of warranty exposure. It has NOTHING to do with the actual wear rates. Again, the effect of TBN is meant to be a marker of info for increased awareness, and NOT a cause to OCI. The OEMs don't care about what it costs us to OCI; that means nothing to them. They set incredibly conservative limits on things that protect their bottom line; they are not concerned with maximizing your dollar.
I challenge you to show me data from real world use that shows those condemnation limits actually correlate to shifts in wear trends. Don't rely on the condemnation limit from some arbitrary source. Show the actual data that concludes a causation of effect here. I want to see proof in real data; not recommendations from sources that are not interested in our best interest. There are lots of UOAs on this site that have low TBN, but no wear concerns. Even UOAs here that show TBN low AND TAN being elevated; still not wear trend shifts. But not once have I seen a UOA here in a moderate OCI that shows any causation whatsoever to low TBN producting high wear. Not once.
TBN dropped and wear was unaffected in this UOA. There is no correlation between TBN and wear. With no correlation there can be no causation. It is just that simple. I can explain it to you, but I cannot understand it for you. You either will get it, or you won't.
BTW - that document you quote looks keenly similar to the one from this CA study:
https://www.dtsc.ca.gov/TechnologyDevelopment/OPPTD_FLY_High-Efficiency-Oil-Filters.cfm
On page 11, they show the condemnation limits for metals, soot, TBN, etc.
You'll note that nowhere in the study did they find any reason to change oil based on TBN alone. In fact, the study does not show any correlation whatsoever to TBN vs wear rates. They plot TBN and Vis relative to OCI duration, but that tells us absolutely nothing in regard to wear metals.
They essentially do the same thing you've done; they predicate an OCI not on wear rates (outputs), but Vis and TBN (inputs).
Inputs are only predictors. They are not results. Wear trends are results.
Show me a study that indicates a low TBN causing wear trends shifts and I'll believe you.
But I caution you in that I've tried to find the existence of this for several years now, and cannot.
My own UOA database shows no correlation whatsoever in short-to-moderate OCIs.
And no correlation means no causation.