Hi Sunfish
We tow with a D5 XC90 that has the geartronic auto box. It's terrific. 99% of the time we just let the geartronic box decide what gear to be in.
Just twice in the 18 months we have had the car have I felt the need for a few minutes to take control and knock the gearstick sideways into the manual mode and hold a particular gear. (And to be truthful, I didn't really need to do it then I was just revelling in the power to do so.)
I don't know about your XC70 (petrol or diesel? age?) but our XC90 has an oil cooler fitted as standard and I am pretty sure that I read on the Volvo owners forum that the diesel XC70's have one also.
Just enjoy it.
Mike A
Cheers
Mike