Grease is typically made from three components – the base oil, a thickening agent made from the reaction of an acid with a metal to create an organic salt, often called a soap, and additives, such as amines, esters and dyes. Unlike lubricating oils, grease is considered a solid.
Base Oils
Conventional base oils experienced a slight decline in use, falling to 85.8% from 86.4% among those companies that report to the NLGI. Semi-synthetic base oil usage remained relatively unchanged. Bio-based base oils declined for a second consecutive year.
Over the past five years, China, North America and Europe have been the primary users of synthetic base oils. Among these, China has shown the strongest growth. Europe continues to be the largest user of bio-based oils, although usage is also declining.
Also similar to lubricating oils, the use of synthetic, semi-synthetic and bio-based base stocks has continued apace in greases, driven by user demand and legislation.**
Thickeners
Since Clarence Earl patented a simple lithium soap thickener in the 1940s, lithium has been stalwart in grease formulations. It’s a jack of all trades that gets the job done. Cheap, abundant, water resistant and performs well at higher temperatures.
*The NLGI survey reflects market trends by extrapolating data from a growing number of participants, up to 248 reporting grease plants in 2024 up from 232.
**In the European Union, only lubricating products claiming to be bio-based must have bio-based content ≥ 25%. If substances such as palm oil are used, they must meet other sustainability regulations. Even so, global bio-lubricants market is projected to expand more than 20% faster than the overall lubricants sector over the next decade, according Kline & Co. In the U.S., the Department of Agriculture’s BioPreferred Program mandates what can claim to be bio-based and suitable for federal purchase and a voluntary labeling system that encourage sector growth.