Grease is often used for components that are isolated or relatively inaccessible. In such applications it may be impractical to provide an oil sump, or to frequently relubricate components. Grease requires less frequent application because its higher consistency resists throw-off. The proper lubrication of rolling-element bearings requires smaller quantities of grease than of oil. Oil, however, is more easily dispensed to all moving machine parts and is more easily handled when draining or refilling bearing wells and enclosed gear cases.
Oil also performs a cooling function.
Grease, because of its semifluid consistency, is poorly equipped for dissipating heat and should not be the sole lubricant in applications involving high speeds and excessive friction. Multiple Uses Greases can be formulated to meet a wide range of application requirements. Although the grease market is divided into automotive and industrial segments, the distinction between the lubricant characteristics and quality required by each is not always emphasized. Of course, certain industrial environments demand special performance features such as water resistance and high thermal stability for use in steel rolling mills, for example. Their requirements are defined in ASTM D 4950 .