Suddenly my bmw started knocking when i was turnig left or right at slow speeds. I thought there is some problems with bushings , rear differencal. Eventually I realized that my rear shocks are broken. So I replaced them with new one. But that didn’t solve my issues with knocking.
I was praying that it is not the fear off all xdrive drivers, transfer case.
So one day I flush oil from it. Oil was burned, black :S After just 40 000 km. It should last aprox 60 000km. I must say that I didn’t drive it offroad a lot.
So I replaced oil not with genuie bmw oil, but with oil from ravenol. And problems are suddenly gone.