[nwautoxer]

The dealership serviced the differential at 34634 miles using 3 units of "83-22-2-282-583 Hinterachs-Getriebeol SAF-XJ:832514." This is quoted from the service invoice.

I called the service advisor and questioned the fluid used because:

* Its the fluid with friction modifier

* Its different than the fluid used at the 1200 mile service which was 83-22-2-148-560XJ

* The tech and I had talked about differential fluid in the past and about what constituted normal differential noise in tight, slow speed corners. I consciously chose to retain the fluid that did not have the friction modifier with the intention of having the maximum locking ability in the differential.

The service advisor talked with the tech who immediately understood my question and explained the reason for changing the type of fluid. He said that about a year ago BMW issued a service bulletin specifying the use of fluid with friction modifier in all M cars thereafter. He indicated that this was to address wear issues.

Has anyone else had this happen and received this explanation? My tech is a sharp and reliable guy that I respect. I'm not questioning his work, rather I am interested in gaining insight about wear in the locker versus locking action that is as positive as possible.

Another interesting sidelight is that I took the 1M in for service about 220 miles after the "SERVICE" message appeared in the instrument cluster display. When the service advisor printed out the service information from the key fob, it showed an engine oil and filter change was due, but the manual transmission fluid, differential fluid, and sparkplugs were not due for replacement for another 2400 miles. I later got a call from the service advisor that the tech had hooked the car to the scope and that it showed the transmission, differential, and sparkplugs were due for service at the same time as the engine oil and filter change. Seems strange that the key fob and vehicle computer aren't in sync.