I can't believe that some of you, are actually following the "suits" service interval recommendations, which is really meant to sweeten the deal for first owner buyers who lease 3 years or so.
I drained mine out, like 2 months after I bought it new, straight from the showroom. There wasn't even a couple thousand on the odometer when I drained it.
I was surprised, almost shocked
, to see how dirty it was!!! Very black, and a slight, BUT, nasty odour to the oil. The car had never even seen a track yet..
I've drained/refilled twice since then with Redline 75W/90, car only had like 14000km on it, so in its 3rd fill basically.
It looked very clean on the 3rd drain/flush. Each round of new oil re-fill, saw an approx. equal amount of mileage between intervals.
*The above I wrote, all purtains to the rear diff only, and not the transmission.
The M6 tranny fluid on the other hand, was very clean looking, even after the first drain.