Sorry if this was already posted and I missed it— I found a copy of a differential technical service document from 2016, which includes "F87 (M2 Coupe):
SERVICE ACTION: REPLACE REAR-AXLE DIFFERENTIAL. It lists part # 83 22 2 357 992 for the final-drive gear oil and is described as "Final-Drive Gear Oil MSP/A (1000ml)".
There may be newer revisions of this document on bmwtis.com, so unless someone already has access, I might pay the $30 to see what I can dig up.
Edit: This document refers to part # 83 22 2 357 992 as "MSP/A", while all of our running in service records refer the same part # as "SAF-XJ".
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