Tough question, all depends on your cruising speed and load. I run at 5000' - 7000' with lots of short steep hills . Have no problem going 120 miles during a normal ride with 2 adults and a young'n. Including all their gear and supplies.
I have found, the tranny shifts better and runs cooler if I overfill it slightly. I normally put in 4 quarts of oil when I change the oil and filter. Just works better.