Because aerated oil does not work very well, these inhibitors, mainly silicones, are used to reduce foaming. As these additives are used up, they perform their function, which is why the oil must be changed.įoam Inhibitors - Oil is subjected to high pressure and engine components that are rotating at high speeds, so it mixes and becomes aerated. The role of these additives is one of the reasons new oil tends to darken soon after an oil change. It's important to note that these additives will not clean sludge and varnish out of an engine their primary role is to prevent sludge formation. Additives are needed to neutralize the acids and help coat metal surfaces to keep acids from attacking them.ĭetergent/Dispersant Additives - Combustion byproducts must be kept in suspension so they can be drained out with the oil. It mixes with the oil and causes formation of acids. Rust and Corrosion Inhibitors - Water-laden air enters engine crankcases, and the water condenses when the engine cools. Oxidation and Bearing-Corrosion Inhibitors - These compounds are designed to slow the rate of oxidation and to provide a coating for bearings. Special additives keep the oil molecules from joining, thereby keeping the oil liquid. Pout-point Depressants - Straight mineral oils tend to congeal into wax-like consistency in low temperatures.
A multi-viscosity package includes the following: