Need specifics on my 2007 C230 Sport. Does anyone know if it has LSD? If so, what kind of alternative oil can I use? Mineral or Synthetic since the owners manual does not dictate any specifics? Manual indicates that the differential requires 85W 90, but the dealer wants $43 for a liter of the stuff. Is there an after market replacement available and what brand/viscosity should I use? The closest that I've seen is made by Valvoline (80W 90) Syntech and the other is made by Mobile 1 Synthetic Gear oil (75W 90). Please help me...!