Motor Oils Overview

A typical container of motor oil, with some in a glass.Motor oil is a type of liquid oil used for lubrication by various types of internal combustion engines. While the main function is to lubricate moving parts, motor oil also cleans, inhibits corrosion, and cools the engine by carrying heat away from the moving parts. The majority of motor oils are derived from petroleum.Synthetic motor oil, consisting of artificiallysynthesized compounds, currently has a majorityshare in the motor oil market place because, while more expensive, it offers enhanced performance.Semisynthetic motor oil was introduced in 1966.Motor oil is a lubricant in internal combustion engines, typically found in automobiles and other vehicles, boats, lawn mowers, trains, airplanes.
In engines there are parts which move very closely against each other at high speeds, often for prolonged periods of time. Such motion causes friction, absorbing otherwise useful power produced by the motor and converting the energy to useless heat. Friction also wears away the contacting surfaces of those parts, which could lead to lower efficiency and degradation of the motor. This increases fuel consumption.Lubricating oil makes a film between surfaces of parts moving next to each other so as to minimize direct contact between them decreasing friction, wear, and production of excessive heat, thus protecting the engine. Motor oil also carries away heat from moving parts, which is important because materials tend to become softer and less abrasionresistant at high temperatures. Some engines have an additional oil cooler.In petrol gasoline engines, the top compression ring can expose the motor oil to temperatures of 320 °F / 160 °C . In diesel engines the top ring can expose the oil to temperatures over 600 °F / 315 °C. Motor oils with the higher viscosity indexes tend to thin less at these higher temperatures.