What is the difference between 5w30 and 10w40?
3 Answers
These two types of engine oil have different viscosities and low-temperature flow properties. 10w40 oil has a higher viscosity, while 5w30 oil performs better in low-temperature flow conditions. More detailed explanations are as follows: 1. The 'W' stands for winter, the first letter of the English word 'winter.' The smaller the number before the W, the better the oil's low-temperature flow properties, meaning it can be used at lower temperatures and provides better engine protection during cold starts. The number after the W indicates the oil's high-temperature resistance, specifically the oil's viscosity at 100 degrees. A higher number means higher viscosity, and a larger value indicates better protection performance at high temperatures. 2. The SAE lubricant viscosity classification includes winter oil grades such as 10W, 20W, etc., and summer oil grades such as 20, 40, etc. Therefore, compared to 10w40, 5w30 has a lower number before the W, making it suitable for lower temperatures, but its high-temperature resistance is poorer.
Let's talk about the difference between 5W30 and 10W40. I usually drive a compact family car and have gained some experience from frequent oil changes. The biggest difference lies in temperature adaptability: the '5W' in 5W30 indicates better low-temperature fluidity, allowing the engine to start easily even in sub-zero winter conditions without seizing up; the '10W' in 10W40 is slightly thicker in cold weather, which might make starting a bit harder. The latter number represents high-temperature performance: 30-grade viscosity is thinner, offering better fuel economy, saving a bit on gas per 100 kilometers; 40-grade viscosity is thicker, providing stronger high-temperature protection, suitable for hot summers or long-distance driving. Oil selection advice based on season and vehicle type: most modern new cars come with 5W30, which is hassle-free and eco-friendly; older vehicles can use 10W40 to extend engine life. Don’t ignore the manual recommendations—using the wrong oil can lead to engine wear or increased fuel consumption.
I think the topic of oil viscosity is super important, especially for engine performance. The difference between 5W30 and 10W40 mainly lies in the viscosity index of the oil film: 5W30 has a lower low-temperature viscosity (the number before W), better fluidity, and quickly lubricates components in sub-zero environments; 10W40 has a higher high-temperature viscosity (the number after W), remaining more stable at 100°C with stronger wear resistance. Practical consequences: 5W30 can improve fuel efficiency and reduce carbon emissions; 10W40 is suitable for high-load environments like off-roading or towing. Engine type also matters: turbocharged cars often use 5W30 to avoid excessive friction; older naturally aspirated engines can use 10W40 for enhanced protection. Regular checks are essential to avoid using the wrong oil, as it may shorten engine lifespan.
