Lubricating with grease is usually suitable for medium to low speed applications where the operating temperature of the bearing is below the limit temperature of the lubricating grease. There is no anti friction bearing grease that can be suitable for all applications. Each type of lubricant only has limited performance and characteristics. Lubricating grease is composed of base oil, thickener, and additives. Bearing grease typically contains petroleum based oil thickened with a certain metal soap. In recent years, organic and inorganic thickeners have been added to synthetic base oils. Table 26 summarizes the composition of typical lubricating greases.

Composition of lubricating grease Base oil Thickener additive Lubricating grease Mineral oil Synthetic hydrocarbon ester perfluorinated oil Silicone lithium base, aluminum base, barium base, calcium base and composite soap soap free (inorganic) particle gel (clay), carbon black, silica gel, PTFE soap free (organic) polyurea compound Rust inhibitor Dye viscosity agent Metal passivator Antioxidant antiwear extreme pressure additive Calcium base and aluminum base lubricating grease have excellent water resistance and are suitable for industrial applications that need to prevent water intrusion. Lithium based grease has multiple uses and is suitable for industrial applications and wheel end bearings.

Synthetic base oils, such as esters, organic esters, and silicones, typically have higher operating temperatures than petroleum based oils when used in conjunction with commonly used thickeners and additives. The working temperature range of synthetic grease can range from -73 ° C to 288 ° C. 

The following are the general characteristics of thickeners commonly used with petroleum based oils. Table 27 The general characteristics of thickeners used in conjunction with petroleum based oils. Thickeners typically have a high drop point, high temperature, and water resistance. When used in combination with synthetic hydrocarbon or ester based oils, the thickeners in Table 27 can increase the high operating temperature by approximately 10 ° C.

Lithium based 193 380 121 250 Good

Composite lithium based 260+500+149+300 good

Composite aluminum matrix 249 480 149 300 excellent

Calcium Sulfonate 299 570 177 350 Excellent

Polyurea 260 500 149 300 Good

The use of polyurea as a thickener has been a significant advancement in the field of lubrication for many years. Polyurea grease has shown excellent performance in various bearing applications and has become a recognized pre lubricant for ball bearings in a short period of time. The starting torque of grease lubricated bearings is very important under low temperature conditions. Some lubricating greases can only function properly when the bearings are running, but they can cause excessive resistance to the starting of the bearings. In some small machines, it may not start when the temperature is extremely low. In such a working environment, lubricating grease is required to have low-temperature starting characteristics. If the working temperature range is wide, synthetic lubricating grease has obvious advantages. This grease can still maintain low starting and operating torque at a low temperature of -73 ° C. In some cases, these greases may perform better than lubricating oil in this regard. An important point about lubricating grease is that starting torque may not necessarily be a function of the viscosity or overall performance of the grease. The starting torque is more like a function of individual performance of a specific lubricating grease, which needs to be determined based on usage experience.

High temperature: The high temperature limit of modern lubricating grease is usually a comprehensive function of the thermal stability and antioxidant properties of the base oil, as well as the effectiveness of oxidation inhibitors. The temperature range of lubricating grease is determined by the droplet point of the lubricating grease thickener and the composition of the base oil. Table 28 shows the temperature range of grease under various base oil conditions. After years of testing with grease lubricated bearings, its empirical method shows that for every 10 ° C increase in temperature, the service life of the grease will be halved. For example, if the service life of a lubricating grease is 2000 hours at a temperature of 90 ° C, the service life will decrease to approximately 1000 hours when the temperature rises to 100 ° C. On the other hand, after lowering the temperature to 80 ° C, the expected service life can reach 4000 hours.