Certainly if you want to do a deep dive, TAN is the number you want, along with TBN. The crossover point is important. Fuel dilution and coolant in oil are both important given the nature of direct injection and the duratec lineage. You CAN get more detailed chemistries, but what we normally see is the most widely used/affordable.
As for critiquing vendors, we welcome open & honest discussion, when conducted in an adult & responsible manner, with an appropriate amount of accompanying restraint.
