I grew up next to an Air Force base and it was constantly noisy. I remember my parents always whining about it and I would always be like “but you bought a house next to an Air Force base?” Lol
OP: “My rear diff seems to be leaking, I’m taking it to the dealer”
Literally everyone else: “here are some things to check first to try and avoid the dealer because they are generally useless”
OP: “I chose to ignore all your advice and let the experts at the dealer figure it out, that is what...
Ah okay if it's the purge valve at the charcoal canister it's in the rear and I believe you need to remove some of the suspension to get to it but I might be wrong. @zrk might have a better idea here.
Honestly, I would look for a BMW shop close to you and get a quote as well. I bet it will be...
Are you looking at the torque in the datalog as reported from the ECU? If so, that is not 1:1 with what the car is actually doing. It's a torque request. Many factors can skew it wildly.
Also it's in Nm unless you switched it to lb/ft.