Which has less noise, 5w30 or 5w40?
2 Answers
Using 5w40 engine oil results in less noise. Here are the relevant details: 1. Compared to 5w30, 5w40-grade oil has higher high-temperature viscosity and better lubrication. Although it creates more resistance for internal engine components, it produces less noise and operates more quietly. In contrast, 5w30 has lower viscosity and relatively poorer lubrication, leading to louder engine operation. 2. The 5W-30 on automotive engine oil indicates the oil's viscosity grade, known as the SAE grade. This is a viscosity standard set by the Society of Automotive Engineers (SAE). The number before the 'W' represents the oil's operating temperature range—the smaller the number, the better its low-temperature fluidity, meaning it performs better in cold conditions and offers superior engine protection during cold starts. The number after the 'W' indicates the oil's viscosity at 100°C—the higher the number, the greater the viscosity (though higher viscosity isn't always better; it depends on the vehicle model, condition, driving environment, and habits).
I've switched between these two types of engine oil several times now, driving an ordinary family car. The 5W-30 is noticeably quieter, especially during cold starts on winter mornings. The engine doesn't make that 'creaking' sound because its lower viscosity improves fluidity, allowing quicker lubrication of components and reducing friction. The difference in summer is less pronounced, but overall driving is quieter, particularly in traffic jams where the engine sound is softer—making conversations easier to hear. Reduced noise isn't just about comfort; excessive noise can indicate insufficient lubrication, which may accelerate engine wear. So unless you frequently drive long distances or have an older car, 5W-30 is quieter and more practical.
