Winter storage

I have a similar question, my bike has synthetic oil in it, a few months old, with about 1 thousand miles since its been changed (which was at the 500 mile service). So, well below the 5 thousand miles the oil supposedly is good for. But I've heard it's good to change the oil before storage; and I even have a friend with a Ducati who, ridiculously in my opinion, changes his oil every thousand miles, w/ fresh oil before storage, and fresh oil after storage. He's oil change mad. So what's the reasoning here, is it just peace of mind or is there some tangible benefit to putting new oil in the crankcase and to coat the internal parts versus 1000 mile old but still reasonably fresh oil. I would definately understand changing it if we're talking about oil with a full seasons use or 3+ K miles on it, but here we're talking about only 1 K miles. Also I have Stabil that i've been using, putting it in my ancient Lambretta, its 4+ years old but I still have some left. Does Stabil also last forever or does it go stale like gasoline does?