Machine oil is a medium-density lubricating fluid used for mechanical or industrial parts to reduce friction. Machine oil can be used on very small parts of a motor or mechanism, all the way up to massive gears and turbines in heavy machinery in industrial settings like food processing, textile mills, and power plants. Machine oils enhance the performance and effectiveness of mechanical operations.
Machine oils can be less expensive than motor oils, but some machinists prefer to use motor oil. One economical technique of reusing motor oil as a machine oil is to drain automotive crankcases of their motor oil, let the oil sit undisturbed for 12 months so that particulate debris can settle. The clear oil left behind at the top of the container can then be decanted, and it makes for an excellent machine oil.