Hi Phil
Well spotted :-) I have introduced 2 litres of clean oil into the system but still no oil from filler plug even at 50 deg C. The gear shifts are perfect and all error codes have gone. Oil was overflowing at 35 deg C with the engine off but nothing with the engine running and the tranmission in park. It just shows that you have to follow the oil level check procedure to the letter. With regard to the faults I can only assume that the low oil level was causing the pump to suck air. This condition was worse under heavy acceleration or on a hill start or when turning out of a junction where the sump oil was forced either to the rear or the side of the sump. As soon as air reached the pump the pressure would drop in which ever circuit was active causing immediate release of that gear followed by lots of software alarms. It all makes perfect sense. I will top off the system when more oil arrives. In the meantime I just have to diagnose where the fluid is escaping from. The box itself is dry with no obvious sign of leakage however the alluminium plate under the engine is wet with fresh oil with the occasional drip from the anti-rolll bar. My bet is the front seal unless there is a leak in the cooler circuit. I will report back after further investigation.
Well done again RRPhil for a spot on diagnosis from the described symptoms.
Thanks from a very relieved X5 newbie
Stuart

__________________
The older I get the faster I was