Which is quieter between 5W30 and 5W40?
3 Answers
5W40 tends to be noisier than 5W30. The number after the 'W' represents the kinematic viscosity of the oil at 100 degrees Celsius. A higher number indicates higher viscosity, which means better protection at high temperatures. It can also be understood as representing the oil's stability at high temperatures (i.e., its resistance to thinning). The larger the number, the better the oil's high-temperature stability. Thicker oil makes the engine work harder, resulting in louder noise. In practice, the choice isn't solely determined by the oil grade, as it also depends on factors such as the vehicle's class, age, and driving conditions. Additionally, using an inappropriate oil grade can lead to excessive engine noise. Therefore, it's essential to follow the vehicle's owner's manual for the correct oil grade. The main difference between 5W30 and 5W40 is their viscosity. 'W' stands for winter, and the smaller the number before the 'W,' the better the low-temperature fluidity and the lower the applicable minimum temperature. The number after the 'W' indicates the oil's kinematic viscosity at 100 degrees Celsius. A higher number means higher oil viscosity, so 5W-30 oil has slightly lower viscosity than 5W-40.
To be honest, I'm quite knowledgeable about engine oil—I've driven over ten cars and frequently switched between different viscosities. Compared to 5w40, 5w30 is definitely quieter, especially in winter or during cold starts. Why? Because 5w30 has lower viscosity, flows more smoothly, reduces engine friction, and thus lowers noise. My own car used to run on 5w40, and there was always a slight gurgling sound at startup, but after switching back to 5w30, it became much quieter. However, environmental factors matter—in high-temperature regions during summer, 5w40 offers better protection, though it might be slightly noisier, but the difference in daily driving is minimal. When choosing oil, don’t just focus on noise; always refer to your vehicle’s manual. Some synthetic oils have added noise-reducing additives, which impact overall performance and experience. In short, for a quiet ride, 5w30 is my top choice.
As someone who has worked on engines for many years, I often deal with such issues. The viscosity difference between 5w30 and 5w40 affects noise levels. 5w30 has lower viscosity at low temperatures, resulting in less resistance during engine operation, hence it's quieter. In practical tests, 5w40 is slightly thicker when the engine is warm, which may cause some friction noise, but the effect isn't significant. The key is to consider your vehicle's design - Japanese cars perform best with 5w30, while European models may recommend 5w40. Oil brand quality also matters, as premium oils can reduce abnormal noises. Other factors like belt or fan issues should also be checked, as they're sometimes misdiagnosed. Overall, based on my experience, 5w30 is the preferred choice for quiet operation.
