Oil that comes out of the ground is not synthetic but is called crude oil. Synthetic oil is man made with synthetic compounds. They are both oil.

Synthetic oil is a chemically made substitute made from petroleum components as opposed to non synthetic which is made from crude oil.

yes

Crude oil from the earth or synthetic oil produced in a lab.

Oil usually refers to petroleum lubricant. It is refined product of crude oil pumped from underground oil fields around the world. Synthetic oil is lubricant manufactured as a substitute for petroleum lubricant, it was first developed by Germany during WWII to make up their shortages in oil. Semi synthetic oil is a mixture of petroleum lubricant and syntetic lubricant.