I have copied this from watchguy.co.uk, really quite informative
The question of using an autowinder for watches that aren’t worn has been discussed long and wide, but without a general consent. This is where I want to put some arguments forward …
Firstly, there is the myth that oil “dries up” when it’s not moved around. If anything degrades oil, it’s oxygen. So the oil in our watch is exposed to that constantly, even when it’s waterproof, as there will be oxygen contained in the air inside the case. We have two scenarios. In the first one, the watch doesn’t run, the oil doesn’t move, and the oxygen will of course over time degrade the oil.
In the second scenario, we keep the watch going, and the oil between the jewels and pinions will start moving as well, exposing more surface to the oxygen. So in my book, this will degrade the oil faster.
The more important issue to me is wear. Any mechanical device that moves causes friction, and friction causes wear. You can have as much oil in there as you want to, you still have wear. And that will affect a fair amount of crucial parts. The balance staff pivots, all the wheel pivots, the barrel and barrel arbor, and, most importantly, the reverser wheels. Anyone with a vintage Rolex is aware that these don’t come cheap (usually around £100 a pop), and they do wear. You can see it on the tips of the little hooks that engage with the inner wheel. The older the watch, the more wear.
Now will any of these parts wear if the watch isn’t worn and is in a drawer? No, they won’t. If you have ever purchased a NOS (new old stock) vintage watch, you know what I’m talking about. You open it up, and the oil might have degraded completely, but all mechanical parts are like brand new. No wear, and it’s like having a brand new watch movement. You clean everything, re-oil, and you have a watch like it just came out of the factory.
On the other hand, if somebody would have put that NOS watch on an autowinder and left it there for 4 decades or so, there wouldn’t be much left of it. With a bit of luck, the abrasion would have eventually locked the mechanism up, preventing it from getting damaged even further, but it won’t be a pretty sight opening that watch and comparing it to a NOS watch that just sat in a drawer.