What next? There are readily available alternatives to lithium- based greases, such as aluminium-complex, organoclay, silica, polyurea, calcium sulfonates, and calcium-thickened greases, however performance characteristics, cost, compatibility, compliance, and application suitability must all be factored into the selection process beforehand.
The most likely alternative grease type to challenge the supremacy of lithium-complex are calcium sulfonate complex greases (CSX). CSX is not new technology however, having been around for quite some time, it is only recently that its usage is becoming more common. The reason this has been the case, since their introduction many years ago, simply comes down to price which has always remained unattractive against lithium-complex grease despite the added performance benefits; thickener content is typically around 4x higher for a CSX compared to a lithium-complex! However, as the commodity price of lithium has soared, the price parity between lithium-complex and CSX has closed, making the higher performance calcium sulfonate complex grease relatively more competitive in today’s market.
Thanks to the type of thickener and the amount of thickener present, CSX greases are inherently water-proof, have high load capabilities, and have excellent resistance to oxidation which reduces the need to rely on specialised (and expensive) additives to boost performance (See figure 1).
thickener content!), and such factors will continue to be a considerable influence, especially whilst ICEs prevail.
All of the aforementioned greases offer various performance properties, with some more comparable to lithium-complex than others, however for a straight lithium grease, CSX greases are still too expensive and offer ‘over-specified‘ performance. So what’s left for a straight lithium grease alternative?
Calcium grease? Although the upper operating temperature is lower than that of a lithium grease, calcium greases have many benefits and should not be considered inferior due to their dropping point (the temperature observed in a laboratory test where a small quantity of lubricating grease is heated until a drop of material separates). Calcium greases are well-known for their water-resistance as well as their biodegradability. With the addition of specialised additives the performance can be boosted where desired, taking calcium greases to meet the multipurpose performance of a lithium grease (See figure 2).
Figure 2: Performance Comparison Lithium EP Vs. Calcium EP.
All-in-all, calcium is a cost-effective alternative to lithium for lower temperature applications.
Figure 1: Performance Comparison Lithium Complex Vs. Calcium Sulfonate Complex.
Unfortunately, the over-based calcium sulfonate (OBCS) detergents often used to create the CSX thickeners are also used in other metalworking and industrial applications, and, significantly, they are a major component formulated into automotive engine oils for ICEs. Demand is high and manufacturers of OBCS detergents are operating at capacity, which means calcium sulfonate supply is limited- this in turn contributes to the rising costs of CSX greases (high
Conclusion Although there are potential alternatives out there that could replace lithium-based greases, it is worth noting that lithium greases have been tried and tested in many applications and have the subsequent OEM approvals. It may yet be some time before OEMs look to the alternatives and this won’t be something that happens overnight. It will require heavy investments of time and money to get that ball rolling!
References: [1](
https://ec.europa.eu/info/strategy/ priorities-2019-2024/european-green-deal_en
www.Ironsideslubricants.co.uk
LUBE MAGAZINE NO.174 APRIL 2023
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