Which oil is more viscous, 5W30 or 20W50?

In the engine oil viscosity grading system, 20W50 has a higher high-temperature viscosity than 5W30. The number before the "W" in the oil grade represents low-temperature fluidity (both 5W and 20W are suitable for low-temperature environments, but 20W has slightly inferior cold-start performance compared to 5W), while the number after the "W" indicates high-temperature viscosity-the larger the value, the thicker the oil film and the better the sealing performance. Specifically, 5W30 has a high-temperature viscosity range of 9.3-12.5, making it suitable for daily commuting or newer engines; 20W50 has a significantly higher high-temperature viscosity, providing superior high-temperature protection for older engines or high-temperature heavy-duty operating conditions, but it increases frictional resistance and leads to higher fuel consumption. Note that overfilling engine oil will reduce power output and may cause oil burning issues.