I oiled a blade I was restoring once with camellia oil and it ran into the pivot area. I got most of the excess out with tissues and went off to lunch. When I went to unpin it an hour or so later, I found that the oil had soaked into the bone scales, discolored them, and softened them way more than I would have thought possible. Neither scale survived the unpinning, although I had no trouble at all on the wedge (dry) side. Not an everyday occurrence, but you should definitely be wary of how oil will interact with the scale material if you are thinking of oiling the pivot.