How Lubricating Grease Is Manufactured

During production, the thickener is either formed in situ within the base oil (for example, soap formed directly in the oil) or manufactured separately and mechanically dispersed into the oil. High-shear mixing, combined with carefully controlled heating and cooling, ensures uniform thickener distribution. Additives are then blended in to adjust consistency, protection, and performance before the grease undergoes quality testing and final packaging.

In essence, grease consists of three core components – base oil, thickener (often referred to as a soap) and additives such as amines, esters and dyes. Unlike lubricating oils, grease is generally classified as a solid due to its structured consistency.

Soap-Based Thickeners (Most Common)

Lithium soap thickeners are produced by reacting fatty acids – most commonly 12-hydroxystearic acid – with lithium hydroxide, forming a fibrous and mechanically stable soap network that holds the base oil effectively. This structure provides good mechanical stability and moderate resistance to water washout, with a typical dropping point in the range of 190–200 degree Celsius. Because of this balanced performance, lithium soap greases are widely used as general-purpose lubricants in automotive chasssis applications, electric motors, and a broad range of industrial rolling bearings.

Lithium complex thickeners build upon conventional lithium soap chemistry by incorporating a complexing agent such as a dicarboxylic acid. This modification creates a more thermally stable crystal structure, significantly increasing the grease’s dropping point to above 260 C. Lithium complex greases offer improved load-carrying capability and better oxidation resistance compared to simple lithium greases, making them well suited for automotive wheel bearings, high-temperature industrial bearings, and heavy-duty automotive and industrial equipment.

Conventional calcium soap thickeners are formed by reacting fatty acids with calcium hydroxide and represent one of the oldest grease technologies still in use. These greases are characterized by excellent resistance to water but have a relatively low dropping point, typically around 90–100 C, which limits their suitability for high-temperature applications. As a result, calcium soap greases are most commonly used in agricultural equipment, marine fittings, and other low-speed applications where exposure to water is frequent but operating temperatures are modest.

Calcium sulfonate complex thickeners are derived from overbased calcium sulfonate detergents, resulting in a thickener system that also functions as an extreme-pressure and corrosion-inhibiting agent. This dual functionality gives calcium sulfonate greases exceptional load-carrying capacity, outstanding water resistance, and extremely high dropping points often exceeding 300 C. These properties make them ideal for severe operating environments such as steel mills, paper mills, marine and offshore equipment, and bearings subjected to heavy shock loads.

Aluminum complex thickeners are produced from aluminum soaps complexed with organic acids, creating a strong, adhesive molecular structure. Greases based on aluminum complex thickeners are notably tacky, adhere well to metal surfaces, and offer excellent resistance to water washout, along with moderate high-temperature capability. They are commonly used in food-processing equipment where H1 food-grade formulations are required, as well as in conveyor bearings and packaging machinery where adhesion and cleanliness are important.

Non-Soap (Inorganic/Organic) Thickeners

Polyurea thickeners are formed through a chemical reaction between amines and isocyanates and contain no metallic components. This chemistry provides excellent oxidation resistance, long service life, and inherently low noise characteristics. Polyurea greases are particularly well suited for sealed-for-life applications and high-speed operation, which is why they are widely used in electric motor bearings, automotive alternators, and other high-speed rolling element bearings.

Clay (bentonite) thickeners are based on naturally occurring layered aluminum silicate minerals that thicken oil through physical adsorption rather than melting. Because clay thickeners do not have a true dropping point, they can tolerate very high ambient temperatures; however, they exhibit poor water resistance and can harden under prolonged mechanical shear. These greases are typically used in high-temperature, low-speed applications such as kilns and ovens, especially where frequent relubrication is possible.

Silica gel thickeners consist of amorphous silicon dioxide particles that form a physical network within the base oil. This structure provides excellent oxidation stability and chemical inertness, along with moderate load-carrying capability. Silica-thickened greases are often selected for clean or specialized applications, including precision instruments, light industrial bearings, and other specialty grease formulations where chemical stability is critical.

Specialty & High-Performance Thickeners

PTFE (polytetrafluoroethylene) thickeners use finely dispersed fluoropolymer particles within the base oil. PTFE is chemically inert, exhibits extremely low friction, and maintains performance across a very wide temperature range. These properties make PTFE-based greases ideal for chemically aggressive environments and sensitive applications such as chemical processing equipment, valves and seals, and clean-room or vacuum systems.

Complex soap hybrid thickeners combine soap-based and non-soap thickener systems, such as lithium-polyurea blends, to achieve tailored performance characteristics. By leveraging the strengths of multiple chemistries, these greases can offer a balanced combination of thermal stability, mechanical durability, and water resistance. Complex soap hybrids are commonly developed for OEM-specific requirements and advanced automotive or industrial designs where standard thickener systems are insufficient.

Quick Comparison Table

Lubricating Grease vs Lubricating Oil

On the surface, lubricating grease and lubricating oil appear to do the same thing – reduce wear and friction. They actually differ significantly in both composition and application.

Lubricating oil has the ability to flow and, depending on the application, takes away heat. Another benefit is that lubricating oils do not rely on thickeners. This eliminates the possibility of thickener incompatibility, which in greases can lead to changes in consistency and, in some cases, performance problems.

In addition, oils allow for more precise control over lubrication. The quantity delivered can be accurately metered, making it easier to ensure the correct amount of lubricant is applied to the system.

Lubricating grease is designed for applications where oil cannot stay in place or where relubrication is difficult or infrequent. Because grease is semi-solid, it remains where it is applied, providing long-term lubrication without the need for continuous circulation.

One of grease’s biggest advantages is its ability to seal and protect. The thickener structure helps block contaminants such as dust, dirt, and water, while additives provide corrosion protection. This makes grease especially valuable in exposed, slow-moving, or heavily loaded components like bearings, chassis points, and open gears.

Grease also performs well under shock loads and intermittent operation, where oil films may be disrupted. It releases oil gradually under pressure, maintaining lubrication even when motion stops and starts.

However, grease is less effective at heat removal and offers less precise quantity control than oil. For this reason, grease is best suited to applications prioritizing retention, protection, and durability rather than cooling.