What is the Difference Between 10W-30 and 10W-40 Engine Oil?
2 Answers
10w-30 and 10w-40 engine oil differences: 1. Different viscosity: 10w-30 engine oil has lower viscosity than 10w-40. 10w-40 engine oil has higher viscosity than 10w-30. 2. Different applicable temperature ranges: The applicable range for 10w-30 engine oil is between -25°C in winter and 30°C in summer; while the applicable range for 10w-40 engine oil is between -25°C in winter and 40°C in summer. 3. Different grade classifications: 10w-30 engine oil belongs to the low-temperature type; 10w-40 engine oil meets the requirements of SAE15W, 10W, 5W for low-temperature viscosity grades and SAE40, 50 for high-temperature viscosity grades, making it an all-season type. Below is extended content: 1. SAE specifies 11 engine oil viscosity grades, indicating which grade of oil should be used at what atmospheric temperature. 2. Among these 11 grades, 6 are winter oils, represented by the letter W, including 0W, 5W, 10W, 20W, 25W. The number before W indicates the minimum temperature at which the oil grade is applicable, with smaller numbers indicating lower temperatures.
The difference between 10W-30 and 10W-40 motor oil mainly lies in their viscosity at high temperatures. The former is thinner at high temperatures, while the latter is thicker. Simply put, 10W indicates the same good cold-start performance, but after the engine warms up, 10W-30 has better fluidity, which can slightly reduce fuel consumption. It is suitable for daily city driving or in cold regions, ensuring smoother starts. I often drive in the north and have noticed this saves fuel costs. On the other hand, 10W-40 is more viscous at high temperatures, providing better protection for engine components, especially during long-distance summer drives or in hot regions, preventing excessive wear. However, it might make the car consume slightly more fuel at high speeds. Overall, it's best to refer to the vehicle's manual for recommendations and avoid arbitrary changes to prevent engine damage. Additionally, older cars or those showing signs of oil leaks may benefit from choosing a thicker oil.
