http://bevo.mercedes-benz.com/bevolistenmain.php?language_id=1Grab can of your "synthetic gear oil" and start searching these Mercedes specifications. Your failure I strongly feel was artificially induced. Volvo, Magirus and Mercedes.
Forty years ago Magirus was the truck of choice for JARTRAN. I was hired for a six month stint to try and straighten out nightmare service problems with the trucks. Failed transmissions and differentials. Mercedes, Volvo and Magirus used the same driveline components. I ---- canned the Paris Rhone alternators and switched to Bosch. That problem ended dramatically.
But they insisted that Eurospec lubricants be used. Pure 100% factory approved.
I fought Miami Florida hdqts and purchased carboys of OEM lubricants (expensive) changed all the lubricants and guess what (?) the failures stopped.
Best of luck to you.