What is the difference between 5w30 and 10w40 engine oil?
2 Answers
The differences between 5w30 and 10w40 engine oils are as follows: 1. Different applicable temperatures: The freezing point temperature corresponding to 5W oil is -30°C, while that of 10W oil is -20°C. 5W30 oil has better cold resistance than 10W40, meaning it can be used at lower temperatures and offers better cold-start performance. 2. Different oil viscosities: The numbers 30 and 40 represent the high-temperature viscosity of the oil. 10W40 oil has higher viscosity than 5W30, providing better high-temperature protection and sealing performance. However, higher viscosity does not always mean better performance. Excessive viscosity can increase engine operating resistance, reduce engine power, and increase fuel consumption.
I've been driving for over a decade and often discuss oil choices with friends. The key differences between 5W30 and 10W40 lie in viscosity and temperature adaptability. In 5W30, the 'W' number 5 indicates it flows more easily during cold winter starts, capable of quickly lubricating the engine even at around -30°C, reducing cold-start wear. The '30' represents high-temperature viscosity, making it suitable for daily commuting and typically resulting in slightly better fuel economy. As for 10W40, the 'W' number 10 means slightly poorer cold-start performance, especially in cold weather where starting might be slower, but its higher high-temperature viscosity of 40 provides thicker protection, offering more stable oil film protection for the engine during hot summers or heavy-duty driving. Generally, 5W30 is more common for new cars or urban compact vehicles, while 10W40 is often used for older cars or high-mileage engines. Always check your vehicle's manual for recommendations – never mix them as it could affect engine longevity.
