Urban_SAK , in a nutshell: when oil (or other lubricant) is missing, so-called "dry friction" occurs at the points where parts meet. As @MichaelRothenpieler correctly noted above, this can lead to metal rub againist metal on the contact surfaces of tools, axles, and springs, that causes and additional wear of the parts.
Therefore, lubrication is essential; it creates a thin film on the surfaces of parts, eliminating "dry friction" and reducing the force required to move parts relative to each other, which slows wear and makes part move more smooth .
Another point is that oil should only be applied to the points where parts touch each other (where tools touch springs, on pivot points, shafts etc.). Apply the lubricant sparingly, in small drops.
Excess oil should be removed so they don't collect dirt and lint.
The only situation oil should be avoided is when operating at extremely low temperatures. Then the oil becomes too viscous and stops performing its functions. In this case, other lubricants can be used.
If you do not mind, I'd like to briefly express my opinion on lubricating Victorinox knives.
New Victorinox knives are shipped from the factory, so to speak, "over-oiled," almost as if they are about to being preserved for long periods of time. This may be due to the likelihood of prolonged storage in warehouses with high humidity before sale. Or perhaps it's a tradition dating back to the days when blades and other tools were made of easily rustling carbon steel, requiring generous oiling.
Therefore, it is recommended to remove all excess oil from new knives before use.
