oci : do I really need a tbn #?

[airbus]

I just got my Mobil 1 0w20 used oil analysis back and everything looks great (5000 mile interval). Blackstone did the oil analysis and stated " all wear numbers at or below average for this type of engine. Insolubles low at 0.3%. no fuel dilution and no water found. SUS viscosity @ 210= 55.2 (should be between 53-59). No tbn. My question is, do I really need a tbn # to extend oci if wear numbers and viscosity is normal. I understand what tbn is used for, but I also heard that tbn numbers are "nice to know" info more than definitive "need to know" info. Any comments?

 

[OffOrWFO]

From the info given I'd say maybe. Did you post your last UOA? Your engine looks to be in good shape and easy on oil. Most oils, especially syns have a lot of TBN left at 5k. So as long as don't make a lot of short trips (less than 7 miles), I would worry about it. More TBN is used up when the oil doesn't get warmed up enough to evaporate off the water. I'd do one TBN on an oil that was run through most of a Candian winter just to make sure. From what I have seen TBN has to be way low before the oil causes high wear metals and we like to error on the side of caution.

 

[TallPaul]

Or one could just add some TBN enhancing stuff midway through a longer OCI. Think I read Lube Control would boost TBN, IIRC.

 

[Spector]

IMO with the method used by Blackstone the TBN has become an almost worthless number. Now if you were really going to extend the OCI, yes, good to know every once in a while but with your OCI not worth the $10 IMO, especially if the numbers look as good as yours