A lubricant is something that helps decrease friction between moving parts in mutual contact, and that therefore reduces the temperature produced when these parts move. It can also have the role of transmitting kinetic energy, moving particles, or warming or cooling the moving surfaces. Many lubricants are water-soluble, while others require a solvent solution to help them form and dissolve into the fluid. Some lubricants in UAE, such as oil, grease, and transmission fluid cannot be lubricated without a catalyst.
Solvents play a vital role in the functioning of engines. When fuel drops into an engine, it goes through a series of stages where it interacts with the various fuel components. At each stage, some of the fuel particles are carried by the airflow and remain below the fuel fluid. The remaining fuel particles are eventually carried by the water into the combustion chamber. This process of fuel particle separation is known as flammability, and any damage to this delicate fuel/solvent interface is a potential cause of the fire.
As fuel particles move from the fuel in the chamber into the rest of the engine, they encounter resistance. This is called thermal resistance, and it is caused by the solubility of the fuel within the lubricant oil layer. Since the oil is not chemically or thermally soluble, it has little effect on the fuel. Lubricants with a high melting point do exist, and these types of lubricants are often called solvent lubricants’ because they form a semi-solid lubricant when heated. This makes them highly suitable for use in high temperatures and extreme environments, including aerospace applications.
The basic solubility factor of lubricant oils, like most fluids, is related to their molecular weight. Thus, higher temperatures increase the amount of insolubility. As the fuel burns at different temperatures, the varying compositions of the fuel burn through in different ways. Thus, in some cases, one type of fuel component will predominate, while another is unaffected by the varying temperatures.
Thus, it is important to understand the relationship between lubricant oil layer solubility and the performance of an aircraft. The lubricant oil layer can prevent the escape of heat that causes combustion by keeping the fuel warm and allowing a consistent supply of cool gas to keeps combustion going. By acting as a heat shield, it also keeps the metal parts of the aircraft from overheating. The lubricant oil layer also keeps the metal parts of the airframe clean since carbon buildup will reduce their luster and increase the risk of rusting.
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