If oil is more viscous than water, how can it be used as a lubricant?

Viscosity is the friction between fluid layers. If friction between layers is more in oil (due to high viscosity) how can it be used to reduce friction??If oil is more viscous than water, how can it be used as a lubricant?
theres more to just viscosity like chemical build up,





Example, graphite, the carbon structure found in your pencil lead, grind it to a powder and you will find it is very smooth and can be use as lubricant in some application when it is a solid.. it is because it has a layer structure that allows it to side across one another...





But for the case of water and oil, i am thinking that maybe because the water is less viscous, when you apply on a surface and add an external force, the water spreads away more easily then oil when resist the external force more...





Example: Lubricanting Key Hole for Key, if you use water, and push the Key (External Force) into the key hole, because it has low viscosity, the pressure by the key easily forces the water away and the hole loses its lubricant. If you use oil, it will spread due to the pressure from the force, but not as much as water.





Not a concrete proven scientific answer but it sounds about right for me =)If oil is more viscous than water, how can it be used as a lubricant?
The viscoisty is not the key characteristic that makes oil and petrochemicals as lubricants desirable.





Watercan howver be used as a lubricant and indeed as a cutter- commonly as a carrier fluid for soaps, detergents etc- as in CNC machines, milling machines and metal lathes.





All these machines though- use petrochemical greases for their moving parts as it has superior heat transfer, higher evapouration point and better friction reduction qualities.
Yes, oil is more viscous than water.But you can't deny that its surface is slippery.


Oil will oppose the motion of a body moving INSIDE it,not OVER it.


It posseses a high value of internal friction(viscosity) but much lower value of external friction.So it is used as a lubricant because of its smooth surface.


Isn't it miraculous !!