UOAs in the diesel section. Soot levels part of the UOA. I've done two 25K mile OCIs. Only "problem" I had was that my TBN got a little low (2.5) on the last run due to a clogged crankcase vent filter. Crankcase was barely breathing at all. I actually caught the problem because of the UOA. My rings are tight enough the case pressure never got high enough to set a code.
TBN fallout combined with potassium with no coolant or water (oil enters charge air system and leaches potassium from intercooler before being ingested by the engine) are the calling card of overdue CCV filter.
Oils are mislabeled. Amsoil AME 15W-40 on the right, Schaeffer 15w-40 next, then Schaeffer 5W-40, then Redline 15W-40.