24-03-2011, 04:55 PM
Presented By
Ranjeet Mohan Bishoyi
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What are motor oils ?
Motor oil, or engine oil, is an oil used for lubrication of various internal combustion engines. While the main function is to lubricate moving parts, motor oil also cleans, inhibits corrosion, improves sealing and cools the engine by carrying heat away from moving parts. Motor oils are derived from petroleum and non-petroleum synthesized chemical compounds used to make synthetic oils. Motor oils are today mainly blended by using base oils composed of hydrocarbons, poly alpha olefins (PAO), poly internal olefins (PIO), thus organic compounds consisting entirely of carbon and hydrogen. The base oils of some high-performance motor oils contain up to 20 wt% of esters .Lubricating oil creates a separating film between surfaces of adjacent moving parts to minimize direct contact between them, decreasing heat caused by friction and reducing wear, thus protecting the engine. In use, motor oil transfers heat through convection as it flows through the engine by means of air flow over the surface of the oil pan, an oil cooler and through the build up of oil gases evacuated by the Positive Crankcase Ventilation (PCV) system.
Functions of Motor Oil
Lubricate
Increases efficiency, slows wear
Cool
Antifreeze only cools the upper engine
Corrosion Protection
Stop/hinder oxidation & acid build up
Clean
Stop deposit formation & hold particles in suspension
History of motor oils
Lubrication dates back to Egyptian times
The first motor oils arrived around 1900
In 1972 Amsoil started selling the first API rated 100% synthetic motor oil for internal combustion engines
Grades and viscosity
The Society of Automobile Engineers in the USA took on the task of setting the standards for engine oil. They made the decision to compare and define lubricating oils by viscosity. Viscosity, in lay terms, is how easily a liquid pours
Single grade
Multi grade
Turbine grade
Viscosity is measured by the remarkably accurate method of pouring oil through a known size hole and measuring how long it takes to come out. The result of this is known as kinematic viscosity.
Oil terminology
Viscosity Index: This measures the effect of temperature on oil viscosity, or the oil's thickness and ability to protect the engine. When oil is heated, it becomes thinner; when it's cooled, it becomes thicker. If the oil is too thin or too thick, the oil can't do its job properly. A high viscosity index means the oil doesn't change too much, no matter what the temperature inside the engine may be. In a perfect world, the viscosity of the oil wouldn't change at all and would provide optimum protection under any conditions.
Total Base Number: The "base" in this context is the opposite of "acid." The total base number measures the oil's ability to withstand acid buildup in the engine.
NOACK Volatility Number: Volatile compounds are unstable and tend to vaporize when exposed to heat, and this test measures that tendency. As temperatures rise, smaller molecules vaporize, leaving behind larger molecules that can make oil more sluggish and less viscous. The lower the NOACK volatility number, the better; it means there are fewer molecules being lost, which means fewer top-offs at the local lube shop