I had this problem. Creaking sound on tight turns such as parking lot spiral. You need to ask the dealer for the "special" differential fluid. Search the forum/online and you will find the service bulletin. Print it out and bring it in. Took 45 minutes. They did it while I waited. Noise goes away in about 600 miles.
2011 E93 - Space Gray - 6MT/Silver Novillo/
OE Tuning/Gruppe M Intake/ACS Springs/Vorsteiner CF Type I Rear Diffuser/Textured Matte Black Custom Powdercoated OEM 359s/Painted Reflectors/Matte Grille, Hood Vents and Side Markers/Arqray Race Exhaust/MS Pulley