Lubrication professionals often become very familiar with the base oil viscosity of their lubricants. After all, viscosity is the most important property of a base oil.

Baselines for incoming oils are set and the health of the lubricant is monitored based on viscosity alone. However, there is more to lubricants than just viscosity. It's crucial to understand the role of additives and their function(s) within the lubricant.

Lubricant additives are organic or inorganic compounds dissolved or suspended as solids in oil. They typically range between 0.1 to 30 percent of the oil volume, depending on the machine.

Additives have three basic roles:

• Enhance existing base oil properties with antioxidants, corrosion inhibitors, anti-foam agents and demulsifying agents.

• Suppress undesirable base oil properties with pour-point depressants and viscosity index (VI) improvers.

• Impart new properties to base oils with extreme pressure (EP) additives, detergents, metal deactivators and tackiness agents.