The difference between lubricating grease and lubricating oil mainly lies in the fluid properties, as shown in the following table
Most lubricating oils belong to Newtonian fluids before their cloud point. Under certain pressure and temperature, their kinematic viscosity does not change with the shear rate. Grease is a Bingham-type plastic non-Newtonian fluid, and more external force is required to make the grease start to flow.
Because lubricating oil has better fluidity and heat dissipation than lubricating grease, lubricating oil is more suitable for the lubrication of various engines, high-speed gears, and ultra-high-speed bearings, and its consumption far exceeds that of lubricating grease. Nonetheless, when it comes to applications that simplify sealing and reduce lubricant consumption and loss, greases need to be considered. Another major factor in the growing range of grease applications is the increasing use of sealed bearings.
There is some competition between grease and oil, but in most cases they are not substitutes for each other.
