Mercedes-Benz W140 S-Class Change Differential Fluid. 

I think you are right.

I removed it . I mixed up the Throttle Body Idle with the ECU Trans shift points. Will fix and upload soon but to reset throttle body idle position you turn key to #2 position after 30 seconds or so the throttle body will make 2 click sounds. Wait about 2 min. then turn off key.

SAE 80w-90 GL-5 is good. I just like synthetic oils for protection.