When I had my Gen 3 (same as Gen 4) one exposed I had a good look at it, admired the mechanism, the stalling at limits not so much. I decided there was little point in lubricating it. It's not exposed to the weather, and doesn't move much, so corrosion and wear should be minimal.
So long as it's running smoothly, I'd suggest leaving it as it is.
JMHO.
Little movie of left side of mechanism going down and up:
The mechanism attached to mirror mount, and on its own: