Last week I had a strange behavior of my auto box. After driving fast uphill a mountain road the auto box in the kickdown action refused to pass the 5000rpm. At 5000rpm neither go any further up nor change the gear for the next one. So in that situation the car had an erratic behavior with the power stopping and starting. Then I had it driven in a very soft way and the same strange behavior happened at 6000prm. No error showed on the dash.
This started on a 2.000Km trip from Athens to France. Luckily everything was OK the next day and still OK after the 4.000km trip.
My thought was that maybe the transmission oil got overheated, and after cooling down everything is normal. I had never the transmission oil replaced and my car is a 2008 i6 with 140.000Km. Shall I ask for new oil or something else happened?