What is oil?
Engine oils and transmission/hydraulic fluids are carefully selected combinations of base stocks and additives which are blended to give desired performance in a wide variety of applications.
Base Stocks are refined from crude oil to obtain products with the best lubricating properties. Base stocks generally make up 80-95% of a typical engine oil.
Additives are chemicals added to the base stocks to improve performance. While representing only 20% or less of the material in engine oils and hydraulic fluids, the proper additives are critical to obtain optimum lubricating performance in today's equipment. There are a number of additives used in oil. The most common are viscosity index improvers, detergents, dispersants, anti-wear and friction modifiers, oxidation and corrosion inhibitors, acid neutralizers, pour point depressants, and anti-foam agents. By properly blending combinations of these additives, oil manufacturers can tailor products to meet the specific needs of their customers.
Multigrade Engine Oils exhibit behavior at low temperatures for easier starting and thick oil characteristics at operating temperatures for better wear resistance and sealing. The addition of special polymers to the base oils allows for this versatility. These polymers expand as temperature increases, resulting in a thicker oil. One big drawback in the use of multigrade oils is that the polymers shear, or break down under load. As a result, with time of service in heavy-duty applications, performance is reduced. Polymer shearing also can contribute to carbon deposit formation in diesel engines. Hydrostatic transmissions are even more sensitive to polymer shear than engines.
