What is the difference between 0w-40 and 5w-40?
3 Answers
0W-40 and 5W-40 mainly differ in their resistance to external low temperatures. The 0W in 0W-40 oil represents a resistance to external low temperatures of -35°C, while the 5W in 5W-40 oil represents a resistance to external low temperatures of -30°C. The smaller the number before the W, the better the low-temperature performance, so the only difference between 0W-40 and 5W-40 oils is a 5-degree difference in supported low-temperature fluidity, with no other distinctions. Below is some relevant information: 1. For 0W-40 and 5W-40, the smaller the number before the "W," the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature. 2. The number after the "W" is an indicator of the oil's high-temperature resistance. The larger the number, the better the oil's protective performance at high temperatures. The 40 indicates that when the engine temperature is 100 degrees Celsius, the oil's kinematic viscosity is 12.5-16.3. 3. The grade of engine oil is determined by its quality level and the kinematic viscosity grade at 100 degrees Celsius.
Every time I change the oil, I have to think about these two types: 0W-40 and 5W-40. The main difference lies in their low-temperature performance. The 0W grade has excellent low-temperature fluidity, remaining smooth even at -35°C, making it especially suitable for northern winters—it provides outstanding engine protection during cold starts. The 5W is slightly inferior, performing well within -30°C, making it a more cost-effective choice for southern regions. As for the '40' suffix, both have similar high-temperature viscosity, meaning no difference in heat dissipation and engine protection during high-speed driving. If you frequently drive in the northeast or own a high-performance car, I’d definitely choose 0W-40. For everyday city commuting, 5W-40 is much more economical and can even save you some fuel costs. However, before changing the oil, it’s best to check your car’s manual—some turbocharged models may specify which type to use.
When getting my car serviced, people often ask me what's the difference between these two engine oils. Simply put, it's about winter adaptability: The '0W' in 0W-40 means it maintains fluidity in ultra-low temperatures, still lubricating the engine at -35°C, making it reliable for vehicles in frigid regions or those parked for long periods. 5W-40 is sufficient within -30°C, so drivers in southern regions don't need to spend extra on 0W. In terms of high-temperature protection, both perform similarly at speeds above 100 km/h with their '40' viscosity rating. Personally, in Guangdong, I use 5W-40, which is about 20% cheaper, but I'd definitely bring 0W-40 for a road trip to Heilongjiang. Also, for older cars with over 150,000 kilometers, higher viscosity oils are better for engine protection, and both of these meet that requirement.
