Short answer
Lithium complex grease uses a thickener made from a lithium soap combined with a second “complexing” acid. The complex structure gives a much higher dropping point than a simple lithium soap grease, which is why lithium complex is widely used for wheel bearings, chassis points and general equipment greasing. It is a thickener type, not a performance specification.
Simple lithium versus lithium complex
A simple lithium grease is usually thickened with lithium 12-hydroxystearate, a soap made from a fatty acid. A lithium complex grease adds a second component, commonly a short-chain dicarboxylic acid such as azelaic or sebacic acid, or a borate, that reacts with lithium during manufacture to form a more heat-tolerant thickener structure.
The practical difference shows up in the dropping point: simple lithium greases typically drop at lower temperatures than lithium complex greases, which is why wheel bearing categories such as NLGI GC are usually met with complex-soap or non-soap thickeners rather than simple lithium.
Where it is used
Lithium complex is a general-purpose choice for automotive and truck chassis, wheel bearings, agricultural and construction equipment pins and bushings, and many industrial rolling-element bearings. Its popularity means most grease guns and centralized systems are already set up for it, and it is compatible with a wide range of other greases.
It is not the answer to every application. Very wet environments, food-processing areas, sealed-for-life electric motor bearings and extreme loads may call for other thickeners or specific formulations, so the equipment maker’s recommendation comes first.
Reading a lithium complex data sheet
The thickener only sets part of a grease’s character. Look at the NLGI grade, the base oil type and its viscosity at 40 °C and 100 °C, the dropping point, water washout or water spray-off results, four-ball wear and extreme-pressure results, and any listed specifications such as NLGI GC-LB.
Supply and alternatives
Any change of thickener should include a compatibility check, ideally following the ASTM D6185 practice or the grease supplier’s compatibility data.
Frequently asked questions
Can I mix lithium complex with regular lithium grease?
The two are generally regarded as compatible, but mixing can lower the dropping point of the blend. Purging the old grease is the safest approach.
Is lithium complex grease waterproof?
No grease is waterproof. Water resistance depends on the full formulation, so check water washout or spray-off data rather than relying on the thickener name.
General maintenance information. Always follow your vehicle or equipment manufacturer’s requirements and the current product data. Questions? Email [email protected].