Additives improve the physical properties or performance of a lubricant.
We all know that oils are fluids, and greases are semisolids. You probably think of graphite, molybdenum disulfide, talc, and boron nitride as additives. In fact, they are solid lubricants. A solid lubricant s molecular structure is such that its platelets will readily slide over each other. Solid lubricants can be suspended in oils and greases.