What is the difference between 5w30 and 0w30 engine oil?

[HadleyMarie]

5w30 and 0w30 engine oils differ in their low-temperature fluidity. 5w30 oil can flow normally at temperatures as low as -30 degrees Celsius, while 0w30 oil can flow normally at -35 degrees Celsius, indicating that 0w30 oil has better low-temperature fluidity. Here is some information about engine oil: 1. Engine oil is the lubricant used in engines, composed of base oil and additives. 2. The density of engine oil is approximately 0.91×10³ (kg/m³). It serves multiple functions such as lubrication and wear reduction, auxiliary cooling, sealing and leak prevention, rust and corrosion protection, and shock absorption, earning it the nickname 'the blood of the car.'

[LeRonan]

The main difference between these two engine oils lies in their cold-start performance. The first number in 0W30 is 0, indicating it has better fluidity in extremely cold weather, making it particularly suitable for northern winters. When I drove to Northeast China for business, I switched to 0W30, and even at -30°C, the engine started smoothly without dry friction. Although 5W30 is also an all-season oil, it becomes less efficient below -25°C, increasing cold-start wear. In terms of high-temperature performance, they are quite similar, with nearly identical viscosity characteristics during highway driving or traffic jams. However, due to its more complex manufacturing process, 0W30 is typically about 20% more expensive. Personally, I think 5W30 is entirely sufficient for those living in southern regions, while friends who frequently travel north might prefer 0W30.

[RosalieLynn]

The most critical difference between 5W30 and 0W30 lies in their low-temperature adaptability. The "W" in motor oil grades represents winter performance. 0W maintains fluidity at -35°C, while 5W can barely handle -30°C. During our team's testing in Mohe, we found that at -28°C, 0W30's startup time was about 3 seconds faster than 5W30, being more battery- and engine-friendly. There's no need to worry about high-temperature conditions since the "30" indicates they share identical viscosity at normal engine operating temperatures. However, 0W30 typically requires higher-quality base oils, demanding better cleaning and oxidation resistance. For drivers in Hainan or Guangdong, the money saved by using 5W30 could cover several extra maintenance services. But northerners, especially those in Heilongjiang, shouldn't skimp on this price difference - winter engine protection is worth every penny.

[StAthena]

Simply put, it's about the difference in cold-start performance. The smaller the number before the W, the better the low-temperature fluidity. 0W30 can maintain oil flow at -35°C, while 5W30 can only handle down to -30°C. I've seen too many engines with cylinder scoring in winter at repair shops, mostly caused by cold-start wear from using the wrong oil. As for high-temperature performance, no need to overthink it—the 30 after the W means both oils have identical viscosity at operating temperatures. However, 0W30 generally contains more additives, giving it a slight edge in controlling high-temperature deposits. If your winters stay above freezing, 5W30 is sufficient; but friends in Northeast China or Inner Mongolia must opt for 0W30—those few seconds of cold-start protection for the engine are absolutely critical.