What are additives? An additive is a chemical added in small quantities to a product to improve certain properties. Motor oil typically contains a Performance Additive Package that can make up 15% to 25% of its composition. The remaining percentage is base oil. The additives help to enhance the performance and viscosity of the motor oil.
The role of additives in motor oilAmong the more common petroleum products, additives are:
• Oxidation inhibitors (antioxidants) for increasing the product’s resistance to oxidation and for lengthening its service life. Under conditions of high temperatures in the engine, the motor oil can oxidize when reacting with oxygen. If that happens, the motor oil ages quickly, thickens and forms sludge. Antioxidants work to slow down this oxidation and the forming of deposits. They also help to keep the engine clean and prolong the life of the motor oil.
• Rust and corrosion inhibitors to protect lubricated surfaces against rusting and corrosion. The internal parts of the engine can rust and corrode because of exposure to moisture and acids. These additives create a film over the parts and protect them against damage from these hazards.
• Anti-wear agents and/ or extreme pressure (EP) agents work to protect parts of the engine that are susceptible to high temperatures such as cylinder walls, piston rings, lifters and cams. These additives form a protective layer on these components and prevent the friction that can occur because of metal-to-metal contact. They also act as antioxidants and are used up over time.
• Demulsifiers to promote oil-water separation.
• Viscosity Index (VI) Improvers are long-chain polymers that help control the viscosity of multi-grade motor oils. They expand and contract as temperatures vary. High temperatures cause VI improvers to expand and reduce oil thinning; low temperatures cause VI improvers to contract and have little impact on oil viscosity.
• Pour-point depressants to lower the cold temperature fluidity of petroleum products. These additives work to prevent the hardening of wax particles in the motor oil under cold conditions. As a result, the motor oil flows freely even at low temperatures and does not need the engine to work harder to pump it. In this way, the engine continues to function effectively despite fluctuations in the outside temperature.
• Detergents and dispersants to maintain cleanliness of lubricated parts by taking care of the soot present in the lubricant.
• Anti-foam agents to reduce foaming tendencies. If the motor oil foams and forms bubbles, it is unable to coat all the important parts of the engine and keep it cool.
• Tackiness agents to increase the adhesive properties of a lubricant, improve retention, and prevent dripping or spattering.