Grease is a semi-fluid to solid mixture of a fluid lubricant, a thickener, and additives. The fluid lubricant that performs the actual lubrication can be petroleum (mineral) oil, synthetic oil, or vegetable oil. The thickener gives grease its characteristic consistency and is sometimes thought of as a “three-dimensional fibrous network” or “sponge” that holds the oil in place. Common thickeners are soaps and organic or inorganic non-soap thickeners. The majority of greases on the market are composed of mineral oil blended with a soap thickener. Additives enhance performance and protect the grease and lubricated surfaces.
Soap thickeners not only provide consistency to grease, they affect desired properties such as water and heat resistance and pump-ability.
Each soap type brings its own characteristic properties to a grease.
The most common soaps are created by hydroxides from earth metals such as aluminum, calcium, lithium, and sodium.
Its major practical requirement is that it retain its properties under shear at all temperatures that it is subjected to during use. At the same time, grease must be able to flow into the bearing through grease guns and from spot to spot in the lubricated machinery as needed.
The most common greases are:

  • Calcium grease
  • Calcium complex grease
  • Sodium grease
  • Aluminum grease
  • Aluminum complex grease
  • Lithium grease
  • Lithium complex grease
  • Other greases:
    • Poly-urea grease
    • Poly-urea complex grease
    • Organo-clay