Lubricant viscosity is one of the most critical elements of component efficiency and life expectancy. Viscosity is a measure of a fluid’s resistance to flow. If the viscosity of a lubricant is too low, the lubricated component will have inadequate protection and will therefore be subject to excessive wear. If the viscosity of the lubricant is too high, a lubricated component will expend additional energy to complete its task. This additional “effort” will reduce the efficiency of the overall system and may cut short the service life of other components, such as motors.
“Viscosity index” is a number assigned to lubricants that describes how much their viscosity changes with temperature change. A lubricant with a higher viscosity index has demonstrated lower amounts of viscosity change. Lubricants with a high index give better protection and efficiency than their low index counterparts. High viscosity index lubricants are more likely to retain correct viscosity for the specific application, because they resist thickening in cold temperature operation or thinning in high temperature operation.
Synthetic lubricants have higher viscosity indexes than conventional mineral oil lubricants. This contrast is due, in part, to the uniformity of molecules within synthetic lubricants. The larger, heavier molecules traditionally found in mineral oil lubricants tend to increase lubricant viscosity in cold temperatures to a much greater degree than the smaller, lighter molecules of synthetic lubricants. Cold temperature creates a thickening of the mineral oil lubricant within the operating environment. This thickening creates a greater exposure to wear of critical components, especially during startup and a loss of efficiency due to the greater effort required to circulate the thickened lubricant. The effect of temperature on traditional mineral oil lubricants causes them to have a lower viscosity index than the viscosity index of synthetic lubricant alternatives. Synthetic lubricants offer greater protection to critical components operating in extreme temperatures.
C. WillisM
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Tags: Lubricants, Synthetic, Viscosity