: yeah, they shouldn't have that much wear by now. Try turning the heat down to see if that lowers your temps (just to see if that's the cause, not that you'll have to spend the winter with no heat
Oiling the bearing is easy. Take out the fan. You'll see a circular sticker at the center of the fan (on one side). Carefully unstick it, and you'll see the bearing. Put a drop of any type of lubricating oil in it, and place back the sticker. It's also important to ensure there's no dust in the bearing. Dust is enemy #1.
: probably not. This trick works when the fans are a bit old already. With use and time, the oil gets thicker, specially if the ambient is dusty, and thus the fan rotates a bit slower than it should. Oiling the bearing just restores the fan to its 100%, but not likely past that.