Well we do have winters here but I never "actually" stop riding. I slow down big time January -March (Generally less then 100 miles in January, lucky 500 miles in Feb, I can almost grab a 1000 in March). Anyway I do changes every 5K miles with synthetic Rotella-T6 5W-40 in the summer and 0W-40 in Early and late season (September-May) on my water-cooled bikes, I change at 3K miles on my air-cooled guys, my TU250X is due soon. Like tires I go through a good amount of oil in all my machines. I'm coming up to my 3rd change for the year on my (water-cooled) Harley-Davidson XG750A, I just did a fresh change for the Fizzy, she's good to go through the winter.

5K miles water cooled, 3K miles for air cooled. I'm generally doing 4-5 oil changes a season with all my kids.