There are many types of chemical additives mixed into base oils to enhance the properties of the base oil, to suppress some undesirable properties of the base oil and possibly to impart some new properties. Additives typically make up about 0.1 to 30 percent of the finished lubricating oil, depending upon the target application of the lubricant. Lubricant additives are expensive chemicals, and creating the proper mix or formulation of additives is a very complicated science. It is the choice of additives that differentiates a turbine (R&O) oil from a hydraulic oil, a gear oil and an engine oil. Many lubricant additives are available, and they are selected for use based upon their ability to perform their intended function. They are also chosen for their ability to mix easily with the selected base oils, to be compatible with other additives in the formulation and to be cost effective. Some additives perform their function within the body of the oil (e.g., anti-oxidants), while others do their work on the surface of the metal (e.g., anti-wear additives and rust inhibitors).