The "service engine soon" light came on. I have 51000 well maintained miles on my 2002 X5. A couple of days later as I was driving to the dealer, the engine started to whine quietly in low gear (automatic transmission) and the whining noise disappeared once I got up to 20 mph. The dealer told me that the diagnostics showed excessive slippage in the transmission and that they would need to replace the transmission at a cost of $7410.45 (without tax), but that I was "lucky" since they had one in stock. Needless to say, I had the X5 towed to an independent BMW mechanic. He diagnosed that the slippage was coming from the torque converter and replaced the bearing ($2400), but told me that my transmission fluid, supposedly a "lifetime" fluid was black. He ran the X5 for a couple of days hearing the whining noise after the repair was completed and indicated that the noise is diminishing as he runs it. He suggested that I drive the X5 for awhile and if the noise continues, he will replace the transmission with a rebuilt one and credit me what I paid for the torque converter repair. Obviously my X5 is out of warranty since it is 7 years old. I am going to contact BMWNA about this issue. How can the transmission go in a vehicle with 51000 miles?????