What is the difference between engine oil A3B4 and A5B5?
2 Answers
A5B5 differs from A3B4 in terms of thermal-oxidative stability, anti-wear properties, detergency, dispersancy, and viscosity retention. The difference between engine oil A5B5 and A3B4 is that A3B4 has better anti-wear performance than A5B5, but A5B5 has higher fuel economy requirements than A3B4. In lubricant certification, A5B5 surpasses all current API quality grades and is a full synthetic oil (PAO). A5B5 is one of the EU certification standards, where 'A' represents gasoline engines for passenger cars, 'B' represents diesel engines for passenger cars, and the numbers indicate the oil grade. A5B5 is the highest-grade lubricant, primarily designed for high-performance gasoline engines and light-duty diesel engines that use low-viscosity oil. It offers excellent cooling and lubrication properties and also performs well in environmental protection. A3B4 is the European automobile manufacturers' testing and certification standard for automotive lubricants. A3 refers to higher-grade products, equivalent to API-SL level. B4 refers to the highest-grade product, surpassing all API oil standards.
I've been driving for over a decade and have tried various engine oils. The difference between A3B4 and A5B5 mainly depends on engine requirements and environmental standards. A3B4 is a high-ash, high-performance oil suitable for older high-performance cars or diesel SUVs, offering strong protection under high engine temperatures and good wear resistance, but its high ash content can easily clog emission systems—for example, using it in vehicles with DPF may trigger warning lights. A5B5 is a low-ash, fuel-efficient oil specifically designed for modern eco-friendly cars, with less ash to protect exhaust treatment devices and slightly better fuel economy, though it provides slightly weaker engine protection. When choosing oil, always refer to the vehicle manual. My experience is not to cut corners by switching oils randomly—using A3B4 in an eco-friendly car can lead to expensive repairs and safety risks. Regular oil quality checks and timely maintenance can extend your car's lifespan.