Oil Additive An oil additive is what is used to enhance oil’s base stock into a finer functioning lubricant. There are a variety of different oils that can be manufactured by using the same base oil, each having it's own unique attributes. Almost every motor oil that is sold today has an additive package, whether petroleum-based or synthetic. The only oils that are completely free of additives are the ones produced by the American Petroleum Institute (API) Service SA motor oils. Without an oil additive these motor oils are not capable of protecting the engines of today's vehicles. Depending on the application of the motor oil, different additives are used. In other words, a small outboard on a boat will use a different oil additive than a diesel engine for a pickup truck. According to petroleum industry standards, lubricant additive packages comprise anywhere from about 20 percent of a common multi-grade motor oil down to 1 percent of a finished hydraulic oil. An oil additive comes in many different forms. The oldest, which dates back to the 1930's, is a detergent additive that is used to clean and offset impurities in the oil which can cause sludge on important engine parts. For increasing gas economy, a friction modifier is used that reduces friction between moving parts. A majority of multi-grade motor oils contain a viscosity modifier, which keeps the oil from breaking down at high temperatures. To prevent hard deposits and the forming of soft sludge, deposit control additives are used. To protect against the oxidation of metal in the interior of an engine, rust and oxidation or corrosion inhibiting additives are used. Antioxidant additives are used to protect against the breaking down of stock oil. To help keep metal parts separated, a film to surround them is provided by wear inhibiting or anti-wear additives. Other types of oil additives include pour point depressants, anti-foam agents, seal conditioners, metal deactivators, extreme pressure agents, dispersants, and wax crystal modifiers. It is apparent that using motor oil with an oil additive is a very important part of keeping your vehicle in top shape. Using the right oil additive is an important part of not only keeping your vehicle running smoothly, but also keeping parts clean and working properly.