Question

if you oil on a metal surface -----would it increase of decrease friction

Answer 1

The friction will decrease because more is the surface uneven more is friction and more is surface even.....less is friction

Answer 2

Actually both are correct.
Let me explain u...

If a little oil is added on the metal surface the area having pores are filled up making the area smooth and thus it becomes frictionless i.e. Friction decreases..


If excess oil is added then the oil will make its own layer above the metal surface and thus when something is rubbed it stucks within that layer causing the surface a little hard.. And thus it causes the friction to increase...

Hope u got my point