What is the difference between 5w30 and 5w40 antifreeze engine oil?
3 Answers
There are mainly the following differences between 5w30 and 5w40 antifreeze engine oil: Different high-temperature stability: The number after W indicates the kinematic viscosity of the engine oil at 100 degrees Celsius. The larger the number, the higher the viscosity, which means better protection and stability under high temperatures, and a lower chance of thinning out. In other words, 5w40 is more stable at high temperatures than 5w30. Different usage targets: 5w40 has better viscosity than 5w30, making it more suitable for older cars. 5w30 is more effective in reducing fuel consumption, allowing the engine to dissipate heat faster and better, and also produces less noise, making it suitable for new cars or naturally aspirated engines.
The difference between 5W30 and 5W40 mainly lies in their viscosity performance at high temperatures. 5W30 has lower viscosity when driving in summer, resulting in quicker acceleration response and slightly better fuel economy. I've used it for several years, and it's particularly comfortable for short urban commutes. 5W40 has higher viscosity, forming a thicker oil film at high temperatures, which reduces engine wear. My older car shows better stability during long highway drives in summer, and I don't worry about overheating when climbing steep slopes. If your driving environment is as hot as an oven, or if your car is older, using 5W40 provides better protection. However, for newer cars used mainly in city driving, 5W30 is sufficient. Don't forget to change the oil regularly and check the oil dipstick every two to three months to maintain cleanliness and avoid impurity buildup.
I think the key difference between these two engine oils lies in their high-temperature viscosity. The 5W30 has lower viscosity, making the engine run more smoothly, which is suitable for quick cold starts in winter and better fuel efficiency. On the other hand, 5W40 has higher viscosity, providing better protection at high temperatures, especially during long-distance summer drives or under heavy engine loads, resulting in less wear. I've tried both in my car a few times. Using 5W30 for city commuting slightly reduced fuel consumption, saving some money, while 5W40 felt more stable when climbing hills. I recommend choosing based on your car's condition and driving environment—don't blindly switch to higher viscosity. Newer cars might actually perform more efficiently with thinner oil. Also, consider seasonal changes; thicker oil can be more reassuring during hot summers.
