Viscosity of motor oil (Mitsubishi Lancer 3)

Viscosity is the degree of fluidity of motor oil. Oil fluidity changes depending on temperature. As the temperature increases, it liquefies. This affects the durability and resistance of the lubricating film. When cold, it becomes viscous, while its fluidity decreases and internal friction resistance increases.

When the engine is cold, the oil must be thin enough to avoid overloading the starter and to be able to reach all lubrication points as quickly as possible when the engine is started. This requires the use of engine oil with a viscosity that changes as little as possible with temperature changes. Flowability or viscosity is equivalent to the internal friction of the oil and is designated by the SAE system (Society of Automobile Engineers), for example, SAE 30, SAE 10. Large SAE numbers have thick oils, small numbers - liquid. But viscosity does not characterize the lubricating properties of oil.