Machine parts are jammed in winter. Why?

Statement-1: Machine parts are jammed in winter. Statement-2: The viscosity of lubricant used in machine part decrease at low temperature.

Machine parts are jammed in winter due to

Give reason for the following: (a) Machine parts get jammed in the winters. (b) A constant driving force is always required for the maintenance of the flow of oil through pipe lines in the refineries. (c) Velocity of water in a river is less near the banks and more in the middle.

The rocks in cold regions get cracked in winter. Why?

Why are the tools and machine parts made of iron smeared with grease or oil ?

Why is it better to wear dark clothes in winter ?