OK, I fixed the problem with my gearbox about a month ago. I took my car to a BMW specialist, munichlegends in Chelwood gate UK, who identified the problem as a faulty oil temp sensor. On the road test, the sensor was giving a temp reading of 90 degrees when it should have been operating between 30-50 degrees. The total bill was £632, with £160 of this just for the oil. They were very good and I will take my car there for future issues, servicing etc. The car since the fix has been brilliant, and has transformed the way it drives, the gear changes are really smooth.
Last edited by bmw x5 - rmg; 11-10-2013 at 02:32 PM.