Accepted Answer
Oil as you might notice is used in moving parts in machines.The reason being is that oil is a smooth type of liquid.So when machine parts are moving with oil on them, the oil allows the machine parts to move more smoothly. So when there is a squeaky noise on a moving part on a machine, mechanics/workers often put oil to make it more smooth because the moving parts are rubbing off on each other.
Suggested Answer
yeah what he said. I was going to say something like that but he explained it better.
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