Which is quieter, 5w30 or 5w40?
2 Answers
5w40 engine oil produces less noise. Here are the relevant details: 1. Compared to 5w30, 5w40-grade engine oil has higher high-temperature viscosity and provides better lubrication. Although it creates more resistance for the engine's internal components, it results in quieter operation. On the other hand, 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, also 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 can perform better in cold conditions and provide superior engine protection during cold starts. The number after the 'W' indicates the oil's viscosity at 100°C—the higher the number, the higher the viscosity (however, higher viscosity is not always better; it should be chosen based on the vehicle model, condition, driving environment, and habits).
As a car enthusiast who has driven many vehicles, I find that 5W-30 is generally quieter in most situations, especially during cold starts and daily driving, because the thinner oil flows better, significantly reducing engine friction noise. I remember last winter when I switched to 30-weight oil, the engine's humming noise became much lighter. On the other hand, 40-weight oil is thicker and offers better protection at high temperatures but tends to be slightly noisier, which can be more noticeable especially in older engines. For newer or fuel-efficient cars, I recommend using 30-weight oil for better performance, but regular maintenance is crucial. Choosing a reputable brand of full synthetic oil can balance noise reduction and protection—don’t skimp on this small expense to avoid bigger issues later.
