Guys, don't forget that the Apex is a dry sump system anyway. You could store it without oil, and there wouldn't be any less sitting in the engine. It is definately not necessary to change it twice, but if you like to throw away money, go ahead. I would change it once at the end of the season, run it to operating temp once, and put it away. I start mine once a month during the summer anyway just to keep everything in order. I'd be far more worried about the little things that could dry out during the summer rather than any contaminants in the oil. These motors are built with the best technology, and the best materials possible, and are not like the sleds we used to have.
I just put a dissicant under the covers of my sled for the summer, and during the really humid months, I put a small desk fan on low speed blowing under the sled. Keep the track off of the ground, and if at all possible, find a place indoors to keep it.
If you worried about corrosion on metal surfaces, spray it down with WD-40. Keep it off the clutches and belt, but it is not oily enought to cause problems later, and will do a good job of rust and corrosion controll.
Nate