As discussed in Greases Explained, a grease is made up of a mineral or synthetic base oil, a thickener, and an additive package.
Clay-based thickeners, such as Microgel in AeroShell Grease 7 and 22, have been used in aircraft since the 1960s, owing to their good water resistance and high-temperature properties. They have served the aviation industry well and will continue to where high temperature performance is required.
However, over time, the requirements for greases have become more and more complex, requiring the use of a wider range of sophisticated additives. At the same time, customer expectations for durability have risen.