What does engine oil a3b4 represent?

[DelAiden]

Engine oil a3b4 represents a dual-purpose oil for gasoline engines and light-duty diesel engines, which complies with the European automotive industry's testing and certification standards for automotive lubricants. The 'a' indicates oil for gasoline engines, while the 'b' denotes oil for diesel engines. The number following the letter represents the oil grade, with higher numbers indicating higher grades. Engine oil serves multiple functions, including lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, as well as shock absorption and cushioning. When the oil flows to the friction areas, it adheres to the friction surfaces to form an oil film, reducing resistance between the friction components. The strength and toughness of the oil film are crucial for its lubricating performance.