I don't know about this procedure, but what you are describing is a known issue. Take it to the dealer and ask them to look up the TSB on it. They will replace the diff fluid with a new fluid that will "fix" the issue. I had mine done last week.
Current: '11 SpaceGrey 328i XDrive
Gone: '07 SilverGrey M Coupe || '08 SparkG M3 || '01 LSB M3 || '01 TiAg 330ci