Mineral oil
Mineral oil is used in a variety of industrial/mechanical capacities as a non-conductive coolant or thermal fluid in electric components as it does not conduct electricity and functions to displace air and water. Some examples are in transformers, where it is known as transformer oil, and in high-voltage switchgear, where mineral oil is used as an insulator and as a coolant to disperse switching arcs. The dielectric constant of mineral oil ranges from 2.3 at to 2.1 at .