X5 3.0 oil consumption vs towing

[Steelhead]

Hi,
I have a X5 3.0 2002 and I use to tow my boat with it (4800 lbs total).
Last week-end, I made a trip in Northern Quebec and the road to get there is VERY hilly. Everything goes well. I used the manual mode for the big part of the trip which is, I think the best to reduce pressure on the tranny.
The only thing that I noticed is the oil consumption. The total mileage of the trip was 800 miles and my engine tooks 1 pint of oil. Is this normal ?

I use to stay in 4th speed at 55 mph (2700 rpm) on highways and flat roads. In the hills, I had to downshift often in 3rd (3500 rpm) and sometime in 2nd (up to 4500 rpm) to climb the steep and long hills.
My engine temperature hasn't move an air during the whole trip.