Importance Of Lubricants

. INTRODUCTION
Lubricants play an essential role in industry and transportation to assist the transfer of energy. Reduction of friction and wear by the use of lubricants enables machinery to work without premature failure, results in energy savings, and controls emissions. Lubricants have an important contribution that relates to energy conservation, minimization of waste and development of durable products[1]. Therefore, the continuous research and development of lubricants contributes to economic and ecological importance. The choice and availability of state-of-the-art lubricants for specific applications may help save resources and energy while reducing harmful emissions, which in some extent, would help preserving our earth’s climate from

Viscosity is being used to determine the rheological characteristics in predicting the ability of the lubricating oil. This ability is referred to the substance’s resistance to motion under an applied force, which is the erection of the lubricating films under both thin and thick conditions. Viscosity also affects heat generation in bearings, cylinders and gear sets related to oil’s internal friction. It governs the sealing effect of the oil and the rate of consumption or loss; and it determines the ease with which machines may be started under low temperature conditions. In addition, the rate of fuel consumption is also affected by the engine oil viscosity. A specified level of viscosity via applications is desired over a wide range of temperature, particularly in cold temperature[10]. Therefore, it is essential to use a lubricating oil with a proper viscosity specification to meet the engine operating conditions.
Dynamic viscosities are usually reported in Poise (P) or centiPoise (cP; 1 cP = 0.01P), or in SI units in Pascal-seconds (Pa.s; 1 Pa.s = 10 P). Dynamic viscosity, which is a function of the internal friction of a fluid, is the quantity used most frequently in bearing design and oil flow calculations. Conversely, it is more convenient to measure viscosity in a manner such that the measurement is affected by the density of the oil. Therefore, kinematic viscosities, in the unit of centiStokes (cSt), are commonly used to characterize