Lubricants Oils are the most important liquid lubricants which
are divided into two large groups: Mineral Oils and Synthetic
Oils. These products are among the most commonly used
lubricants. Lubricants have important applications in internal
combustion engines, vehicles, industrial gears in compressors,
turbines, hydraulic systems, etc. Ninety percent of the
lubricants which are used consist of lubricant oils among which
automobile oils have the highest consumption rate. The first and
most important thing to consider while choosing oils for certain
applications is their viscosity. In fact, viscosity changes in
different conditions directly affect a lubricant’s performance.
Due to the significance of a good choice of the viscosity
degree, different classifications for various types of engines
and industrial oils have been provided.