The Thick and Thin of Grease


Grease manufacturing is a highly complex and detailed process that starts with base oil, thickener and additives. Base oil provides the lubricity and foundation consistency of grease while thickener constitutes the major structure of the grease, giving it a solid to semi-fluid consistency.Additives enhance its performance

Greases perform their lubrication function over time by staying in place and gradually releasing oil into the working areas of the contact components. This function, performed by a thickener, can be compared to a sponge gradually releasing its liquid when squeezed. Mechanical shear and heat induce the release of its hold of oil.


Although the base oil and additives used to formulate greases are important, the thickener system has its own impact on the performance characteristics of the final product. The fiber structure provided by the thickener determines the mechanical stability and physical properties of the finished product.Simple thickeners typically provide adequate protection in moderate-temperature applications, while a complex thickener can withstand high operating temperatures and heavier loads. Non-soap thickeners can be made from a variety of materials and deliver a wide range of performance results.

Lithium and Lithium-Complex Greases

Are widely used and very robust; they account for at least 50 percent of domestic grease production. These greases have excellent shear stability, strong high-and low-temperature characteristics, resistance to softening and leakage and moderate water resistance. Additives are used to improve their washout-and corrosion-resistance. The generally well-rounded performance of lithium and lithium-complex greases has made them the product of choice for industrial and manufacturing environments.

Lithium-complex grease can withstand higher temperatures than simple lithium grease, AMSOIL offers a number of high-speed, high-temperature lithium-complex greases for a variety of applications, including High-Viscosity Lithium-Complex Synthetic Grease (GVC),  DOMINATOR® Synthetic Racing Grease (GRG), Synthetic Polymeric Truck, Chassis and Equipment Grease (GPTR1, GPTR2) and Semi-Fluid Synthetic EP Grease (GSF).

Calcium, Calcium-Complex and Calcium-Sulfonate-Complex Greases

Are known for their excellent washout and water-resistance properties. Additives can provide these greases with strong resistance to corrosion, making them excellent for wet applications. Simple calcium grease is best used in low-to moderate-temperature applications and has acceptable stability at moderate temperatures.

Calcium complex and calcium-sulfonate-complex greases have inherent extreme-pressure and load-carrying capability, as well as temperature limits similar to those of other complex greases, making them desirable as multipurpose greases. These greases are typically used in high temperature industrial and automotive bearing applications and have more recently been formulated for use in food-grade applications.

Since they excel over other calcium greases in extreme-pressure applications, AMSOIL provides a number of synthetic calcium-sulfonatecomplex greases, including Synthetic Polymeric Off-Road Grease (GPOR1, GPOR2), Synthetic Multi-Purpose Grease (GLC), Synthetic Water-Resistant Grease (GWR), Arctic Synthetic Grease (GEC) and Synthetic Fifth-Wheel Grease (FWG).

Aluminum and Aluminum-Complex Greases

Are recognized for their excellent water resistance and inherent rust, corrosion and oxidation resistance. At temperatures above 79°C (175°F), (simple) aluminum grease loses its shear stability and pumpability, while aluminum-complex grease has a maximum usable temperature of 177°C (350°F). Aluminum-complex grease is used for rolling-element and plain bearings, steel mill roll-neck bearings and high-temperature industrial applications. Some formulations of aluminum-complex grease can be used in food processing machinery.

Aluminum-complex thickeners are used in AMSOIL X-Treme Synthetic Food Grade Grease (GXC).

Polyurea grease, a commonly used non-soap grease, is used in industrial rolling-element bearings, automotive constant velocity (CV) joints and other ball-bearing applications. These greases provide impressive extreme-temperature performance, making them effective over a wide range of temperatures. They have inherent oxidation and wear resistance and good work stability. The durability of polyurea greases makes them wellsuited for sealed-for-life components.

Most AMSOIL synthetic greases are manufactured for consumer use, no AMSOIL greases feature a polyurea thickener.

Bentonite (clay-based) grease, another common type of non-soap grease, is usually used in extremely hightemperature applications because it has no melting point. Bentonite greases’ maximum temperature is limited by the evaporation temperature of the base oil. These greases have excellent water resistance, but require additives to increase oxidation and corrosion resistance. Because bentonite greases can leave a residue at elevated temperatures, the applications with which they are used require frequent lubrication.

Bentonite greases are most often used in some high-temperatures bearings and in aerospace applications where temperatures are extremely hot. AMSOIL does not offer a bentonite grease.


Greases made with different thickeners have such different characteristics with regard to maximum temperature, dropping point and other performance characteristics, choosing the best grease for any given application is important. Consideration should be based on the high and low operating temperatures of a given application, whether those temperatures are sustained or intermittent, and the environmental conditions in which the application operates.


AMSOIL offers premium synthetic grease for a wide variety of applications, including over-the-road, off-road, automotive, racing and industrial. They are engineered from high-quality synthetic base stocks for optimum lubrication and their thickeners provide the necessary physical characteristics for enhanced durability and stability. Advanced AMSOIL additive packages enhance performance and deliver exceptional protection.