Lubricating oil is a type of oil used to reduce friction between surfaces in mutual contact, which helps to prevent wear and tear. It is commonly used in engines, machinery, and various mechanical systems to ensure smooth operation and longevity. The oil forms a protective film that keeps parts from grinding against each other, which can lead to damage. There are different types of lubricating oils, including mineral oil, synthetic oil, and biodegradable oil. Each type has specific properties suited for various applications, such as high-temperature resistance or environmental safety. Proper lubrication is essential for maintaining the efficiency and reliability of equipment.