Synthetic motor oil.

An oil is any substance that is in a viscous liquid state ("oily" state) at or slightly above ambient temperatures, and is both hydrophobic (immiscible with water, literally "water fearing") and lipophilic (miscible with other oils, literally "fat loving"). Thus oils are nonpolar substances.

The general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. There are many types of oils, including vegetable oils, petrochemical oils, and volatile essential oils. They are used for food, fuel, lubrication, and the manufacture of paints, plastics, and other materials. Specially prepared oils are used in some religious ceremonies as purifying agents.



Food oils


Health advantages are claimed for a number of specific oils such as omega 3 oils (fish oil, flaxseed oil, etc) and evening primrose oil.


Oil as fuel

Most oils burn in air generating heat which can be used directly or converted into other forms of energy in the usual ways. Oils are used as fuels for heating, lighting (such as a kerosene lamp), powering combustion engines, and other purposes. Oils used for this purpose nowadays are usually derived from petroleum (including fuel oil, diesel oil, and gasoline), though biological oils such as biodiesel are also used.



Manufacture of petrochemicals

Crude oil can be processed into plastics and other substances.

Heat transport



Color pigments can be easily suspended in oil, making it suitable as supporting medium for paints. The slow drying process and miscibility of oil facilitates a realistic style. Oil paints have been used since the fifteenth century.




Oil allows massage strokes to glide along the skin. The oil is selected based on the viscosity for the type of massage being conducted. A relatively high-viscosity oil such as almond oil may be used for a luxuriant, slow style; a lighter oil such as grape seed oil may be selected for a rapid approach. Scents may also be added.

Environmental concerns

Petroleum is considered a nonrenewable resource, and burning it produces carbon dioxide, a greenhouse gas. Biological oils are renewable and do not produce net carbon dioxide, but require land to grow. Both also produce pollutants such as nitrogen oxides (NOx).

See also


  • Conaway, Charles F. 1999. The Petroleum Industry: A Nontechnical Guide. Tulsa, OK: PennWell Pub. Co. ISBN 0878147632.
  • Gunstone, F. D. 2004. The Chemistry of Oils and Fats: Sources, Composition, Properties, and Uses. Oxford, UK: Blackwell Pub. ISBN 0849323738.
  • Gunstone, F. D. 2002. Vegetable Oils in Food Technology: Composition, Properties, and Uses. Chemistry and Technology of Oils and Fats. Osney Mead, Oxford: Blackwell. ISBN 0849328160.
  • Raymond, Martin, and William L. Leffler. 2006. Oil and Gas Production in Nontechnical Language. Tulsa, OK: PennWell Corporation. ISBN 1593700520.



