Sorry, I don’t agree with that. You only have to see the condition of the oil you drain out to know it needs to be done. The S diff has friction plates, it just has electronic control of them where the non S works on ramps, the old fashioned way.W205 - Mechanical diff needs the oil changed, the E diff doesn't apparently. I had the diff and insisted it was changed which the dealership complied with at no cost but Mercedes confirmed the it didn't need to be changed.
Whoever gave you that 'pearl of wisdom' must have been on acid.....The diff oil change is at mandatory intervals, its in the service schedule - my local dealer didn't want to do it either, although they at least acknowledged it was in the schedule. I ended up getting it done at my local indy, was way less hassle and cheaper to boot.W205 - Mechanical diff needs the oil changed, the E diff doesn't apparently. I had the diff and insisted it was changed which the dealership complied with at no cost but Mercedes confirmed the it didn't need to be changed.
My car is a March 2018 pre facelift C63 AMG W205 (not S).When I bought it at 13,000 miles it had no record of a running in service at 2,000 miles on the diff and the dealer said it’s not needed so I asked them to do it anyway as a condition of purchase. They didn’t do it, they did transmission instead by mistake so at 16,000 miles I got it done.I got the oil analysed and iron content is over recommended levels and Miller Oils said 2,000 miles and then 31,000 miles is a good idea but Mercedes UK insist that the recommendation on my car was first change at 31,000 miles.On older cars they accept a 2,000 mile running in change is required.Looking at the oil, the change was overdue so all those with a 31,000 mile recommendations get the oil changed ASAP and don’t wait.(and give them a jam jar so you can see the condition yourself).My dealer told me the same thing with my Pre face lift w205 c63. Shortly after I collected the car I got an email from AMG Stating the dif oil needed changing after 2000 miles which is included in the price of the car and would be provided FOC by my local dealer.