Wiktionary
n. oil for lubricating an internal-combustion engine
WordNet
n. oil used to lubricate the moving parts of a motor
Wikipedia
Motor oil, engine oil, or engine lubricant is any of various substances (comprising oil enhanced with additives, for example, in many cases, extreme pressure additives) that are used for lubrication of internal combustion engines. The main function of motor oil is to reduce wear on moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts.
Motor oils are derived from petroleum-based and non-petroleum-synthesized chemical compounds. Motor oils today are mainly blended by using base oils composed of hydrocarbons, polyalphaolefins (PAO), and polyinternal olefins (PIO), thus organic compounds consisting entirely of carbon and hydrogen. The base oils of some high-performance motor oils contain up to 20% by weight of esters.
Usage examples of "motor oil".
A longliner drifted toward the fish plant, a figure in yellow oilskins leaning on the rail staring into dimpled water the color of motor oil.
The earth around the platform was soaked with motor oil and churned up by tire treads.
The battering downdraft slams him, rich with the stink of hot metal and motor oil.
He had run out the old - whatever was left of it - and had run in a few quarts of Sapphire Motor Oil.
The floor was dirt, but packed and laden with seventy years of motor oil.
The garage was a large dark space, open rafters, open framing, smelling of old motor oil and creosote.
The dampness made the interior smell of plastic, motor oil and old carpeting.
He then got four glasses and poured a dollop of clear fluid into each from an old green bottle that had at one time contained motor oil.