10W30 engine oil has a higher viscosity at room temperature than 5W30 engine oil, and the main difference between the two lies in their low-temperature fluidity. The number before "W" represents low-temperature performance: 5W30 can maintain fluidity at minus 30 degrees Celsius, while the low-temperature starting limit of 10W30 is minus 25 degrees Celsius. Therefore, 5W30 can lubricate engine components faster in cold environments. However, the two have the same high-temperature viscosity (the "30" after "W"), meaning their kinematic viscosity is the same at 100 degrees Celsius, and both can provide stable high-temperature protection. In tropical regions such as Malaysia, where the temperature is high all year round, the high-temperature performance of the two oils is similar. But if the vehicle is often started cold in the early morning or driven to plateau areas, the low-temperature advantage of 5W30 is more obvious. Excessively high viscosity will increase fuel consumption and noise, while excessively low viscosity will affect sealing. For older vehicles, the viscosity can be appropriately increased to compensate for component wear.
