I am getting my car's dual-clutch fluid changed this Friday. The factory fill will have around 52k on the clock; it is Pentosin FFL-4, and is actually very similar to a Dexron/Mercon ATF, but with GL-4 protection.

Is there any value in getting the TBN and/or TAN measured?

FWIW, BMW classifies it as a lifetime fluid (yeah right).
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2011.5 BMW M3 saloon ZCP
der stärkste buchstabe der welt
Castrol Edge Professional TWS 10w60 + Mahle OX 254D3