A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles. The property of reducing friction is known as lubricity. Typically lubricants contain 90% base oil (most often petroleum fractions, called mineral oils) and less than 10% additives.

A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles. The property of reducing friction is known as lubricity. Typically lubricants contain 90% base oil (most often petroleum fractions, called mineral oils) and less than 10% additives.