Ask the Expert: Is it Time to Ditch Lithium Grease?

Lithium-based greases hold about 70% of the grease market share due to their versatility, historic affordability, and superior performance. However, the recent increase in electric vehicle production has drastically reduced the availability of lithium, forcing people to seek lithium grease alternatives. I recently sat down with Dr Anoop Kumar, Senior Staff Scientist at Chevron Products Company, a division of Chevron U.S.A. Inc., to discuss the future of the grease market and what to do if lithium grease is no longer an option for your machinery.  

Q: What led to the popularity of lithium grease and why has it retained such a large market share? 

A: Calcium greases were the first to be widely used in machinery, but ultimately declined because they were unable to withstand high temperatures. Then, sodium-based greases became popular. Though they could handle high temperatures, they had extremely poor water resistance. Lack of success with calcium and sodium greases led to the rise of lithium greases—though they were more expensive at the time, these greases were multipurpose, exhibited stability in high temps, and excellent water resistance. As they eventually became more affordable, lithium greases have successfully maintained their popularity throughout the years. 

Q: Why are so many organizations reconsidering the use of lithium grease?   

A: There are a couple reasons for this. The first is the exponential and unprecedented increase in price in the last few years. The price of lithium greases used to be relatively less compared to other high-performance greases like Calcium Sulfonate, Polyurea, and Aluminum Complex. Now, due to the huge drift of lithium batteries in electric vehicles, there is reduced availability of lithium for greases, and the price gap has pretty much diminished. 

Another reason is that there is a proposal in Europe to classify lithium as a category 1A substance. 1A stands for chemical substances for which there is scientific evidence that the substance is carcinogenic, mutagenic or reprotoxic for humans. If this is approved, it may only be a matter of time before other parts of the world follow, leading to decreased market share of lithium grease. 

Q: Calcium sulfonate greases are growing in popularity due to their excellent EP performance and oxidation stability. Are they an acceptable alternative to lithium greases?  

A: In-heavy duty industrial applications, Ca-Sulfonate greases have shown superior performance in terms of extreme pressure, anti-wear, water resistance, rust protection, and more. Yes, they are potentially an acceptable alternative, especially now that their price is level with lithium greases. In the past, there were concerns about low pumpability, but thanks to advancements in technology, this is less of a concern today.  

Source: “Choosing a Multi-Purpose Grease: Lithium Complex or Calcium Sulfonate?”, Machinery Lubrication Magazine, 2014 

Q: Which applications are calcium sulfonate greases best suited for?  

A: Ca-Sulfonate greases thrive in heavy-duty, off-highway, and other industrial applications. One advantage of Ca-Sulfonate chemistry is that it can be tailored as food grade greases. Though Ca-Sulfonate by itself is not food grade, it can be developed to be food grade by using permitted ingredients, making it an acceptable choice for food & beverage and pharmaceutical manufacturing.  

Source: “Choosing a Multi-Purpose Grease: Lithium Complex or Calcium Sulfonate?”, Machinery Lubrication Magazine, 2014 

Q: Why should people be mindful of compatibility when switching greases?  

A: I think compatibility of greases is a very important aspect of grease changeover. Mixing of incompatible greases, whether mixing occurs intentionally or unintentionally, has the potential to adversely impact the end-use properties of greases and can even result in catastrophic failures. However, if due care is taken, it’s not very difficult to switch from one grease to another.   

Q: How can one determine grease compatibility to ensure a smooth transition from lithium-based grease to another? 

A: The ASTM Standard test method (ASTM D 6185) can be used to test compatibility of two binary mixtures. The two greases are combined at different ratios (10:90; 50:50; 90:10) to simulate ratios that might occur when attempts are made to flush out one grease with another. When the ratios are created, several tests are performed on the mixture including dropping point and shear stability. If any mixture fails the primary tests, the greases are incompatible. Additionally, some companies run their own compatibility test suitable for their greases and customers. 

Chevron’s Rykon® Grease Line: Coming Soon 

In response to changes in the market, Chevron is updating its offerings to include calcium sulfonate complex greases in the new Rykon product line, launching early 2024. Calcium sulfonate complex greases offer superior quality in most product performance attributes. They provide outstanding oxidation and thermal stability at higher operating temperatures, as well as water resistance and load carrying properties. These greases are well-suited for heavy duty and extreme pressure applications to get maximum protection against the harshest conditions, such as high temperatures, heavy loads, excessive dirt, constant moisture, and contaminants that can attack equipment and threaten operation. 

Dr. Anoop Kumar holds a Chemistry Ph. D and his Marketing Management Postgraduate Diploma. In 1991, Dr. Kumar began his career at Indian Oil Corporation Limited (IOCL) as a research officer and worked there for 17 years. In 1997, while at IOCL, he co-founded and ran the NLGI India Chapter, before leaving IOCL in 2008. He joined the NLGI board in 2012 while working at Royal Manufacturing Co., now Axel Royal LLC, as director for R&D and Business Development. He is now serving as President of NLGI (2022-2024) and has been working with Chevron Products Company, a Division of Chevron U.S.A. Inc since 2018 as a Senior Staff Scientist. Dr. Kumar has 30 worldwide patents on lubricating greases and more than 120 publications, articles and presentations.