Originally Posted by 
Richard93Vogue
				 
			A towing question.  I have an Si6 auto to which I have just fitted a towbar. When towing my camper trailer this last week I noticed that after about 4 or 5 hours towing the auto started to complain, the symptom being that it was jumping in and out of gear rapidly for a short period of time, say 10seconds (seemed longer!) and then it operate normally for 20min and do it again. We stopped for the day soon after but the next day it happened again after the same amount of driving.
The car has 160000km and has of course never towed anything before now. 
Could it just be the tranny fluid showing its age? 
What else might it be?