Blackstone charges $10 extra for TBN number. This is what Blackstone has to say about TBN.
"The oil’s function is to lubricate, clean, and cool the engine. Additives are added to the oil to enhance those functions. The*TBN will start out*reading in the 6.0 to 14.0 range (depending on the oil and whether it’s meant for gas or diesel engines). When you first start using the oil, the TBN*tends to drop sharply. Then it levels out and*drops more slowly*after that. The lower the TBN reading, the less active additive the oil has left. A low TBN*test result, meaning very little additive is left, is down around 1.0 or lower. *
The TBN is not the only factor to consider when determining how long an oil can be used. If wear accumulations and insolubles in the oil build up and become abrasive, we would*recommend changing out the oil, no matter how high the TBN reading."
Yes, the wear accumulations and insolubles, that would include soot levels. The analysis will tell you when those are high enough that the oil should be changed. If they are not and TBN is above 1.0, changing the oil is a waste. I just tested my oil at 175 hours. TBN started at 12.0. presently at 7.5. I'll test again at 350 hours. Oil filter changed at testing interval.