synthetic lubricant - lubricating fluid made by chemically reacting materials of a specific chemical composition to produce a compound with planned and predictable properties; the resulting base stock may be supplemented with additives to improve specific properties. Many synthetic lubricants - also called synlubes - are derived wholly or primarily from petrochemicals; other synlube raw materials are derived from coal and oil shale, or are lipo-chemicals (from animal and vegetable oils). Synthetic lubricants may be superior to petroleum oils in specific performance areas. Many exhibit higher viscosity index (V.I.), better thermal stability and oxidation stability, and low volatility (which reduces oil consumption). Most synlubes offer longer service life and, in some cases, better biodegradability than conventional lubes; consequently, they are increasingly being used in industrial and automotive applications. Individual synthetic lubricants offer specific outstanding properties: phosphate esters, for example, are fire resistant, di-esters have good oxidation stability and lubricity, and silicones offer exceptionally high V.I. Polyalphaolefins are versatile lubricants with low pour points, and excellent thermal and oxidation stability; they have good compatibility with petroleum lubricants and most seals used with petroleum lubricants. Most synthetic lubricants can be converted to grease by adding thickeners. Because synthetic lubricants are higher in cost than petroleum oils, they are used selectively where performance or safety requirements may exceed the capabilities of a conventional oil.