Just had a VOA done by OAI/Polaris. The TBN was tested using the D4739 protocol and tested roughly 2 points lower than Motul tested with the D2896 protocol. Reading on Polaris' own website it says that the D2896 protocol should be used for new oil samples and the latter for used oil. My thinking is other that testing to see if the TBN from the manufacturer is correct, it really doesn't matter. In fact I would probably argue it's better to test the virgin and used samples in the same protocol in order to actually see the useful life of the engine oil and how long the TBN actually takes to diminish to the end of its serviceable life. Would I be correct?