Flow measurement range of the friction material is the so-called viscosity, to prevent contact between the movement parts wear, the bearing must have enough lubricant viscosity, viscosity decreases with temperature. Bearing lubricating oil viscosity is an important physical and chemical properties of quality assessment, the production, transportation and use, are very important.

The main technical indicators of the bearing lubricant viscosity, but the viscosity of the bearing lubricant shall not exceed the extent of the impact of the engine start, the vast majority of the oil is based on the viscosity of the sub brand bearings, the main basis for the selection of various equipment is the oil. Absolute viscosity measurement method is divided into two major categories of viscosity and relative viscosity. Absolute viscosity dynamic viscosity, kinematic viscosity; Engler viscosity relative viscosity, Saybolt Viscosity and viscosity of several mines representative.

Excessive use of bearing oil of viscosity will increase the mechanical wear, in the practical application, the choice of appropriate viscosity of the lubricating oil products, machinery and equipment, can guarantee the normal work reliably. Usually case, low speed high load applications, using oil viscosity to ensure adequate oil film thickness and normal lubrication; the application of high speed and low load using smaller oil viscosity, in order to ensure the normal machinery and equipment of starting and running torque, engine oil viscosity is too large, unsalable, arrogant, although the pressure of high oil prices, but a small amount of oil through, and can not increase the friction surface, resulting in minimal friction under continuous operation. Due to the bearing oil circulation is slow, bearing oil filter is small, it is difficult to collapse time, scrap metal, carbon particles, dust, and from the friction surface cleaning. Because of the viscosity of the oil, the friction between the surface of the machine is increased, the friction is increased, the fuel consumption is increased, and the engine output is reduced. Bearing lubricant viscosity, oil circulation rate will slow down the cooling and heat dissipation, easy to make the engine overheating. Temperature rise to a variety of operating temperatures, can form a moving part between the film.

Therefore, do not use too much of the engine oil viscosity, viscosity can not be regarded as the more the better. In order to ensure the lubrication conditions, the use of low viscosity oil can be used as far as possible according to the temperature range. But more serious wear and tear, the gap has been relatively large engine, can be appropriate to use a slightly larger viscosity of oil.