 Ionic liquids, IELs, are room-temperature molten salts that offer advantages as lubricants due to their ability to protect against wear and reduce friction in various systems. IELs can be incorporated into non-polar base oils, replacing traditional anti-wear additives, with excellent performance maintained. IELs consist of large asymmetrical ions that readily adsorb onto metal surfaces and form a protective film under boundary lubrication conditions. Certain IEL compounds can also react to form a protective tribofilm under extreme pressure conditions when fluorine, phosphorus, or boron atoms are present in the constituent ions. This article was authored by Anthony E. Summers, Patrick C. Howlett, Douglas R. McFarlane and others.