Which consumes more fuel, 5w30 or 5w40?
2 Answers
5w40 engine oil consumes more fuel than 5w30. Here is some relevant information about 5w40: 1. Concept: In "5W40," the "W" stands for "winter," indicating its use in cold conditions. The number "5" before the "W" represents the viscosity at low temperatures—the smaller the number, the better the fluidity in cold weather and the stronger the cold resistance. The "40" refers to the viscosity at 100°C—the higher the number, the greater the viscosity and the better the high-temperature resistance. 2. Application: German cars typically have turbocharged engines with larger clearances, making 5W40 (higher viscosity) oil the preferred choice. European cars also commonly use 40-viscosity oil.
I've researched both of these oil viscosity grades. The 5W40 has significantly higher viscosity at high temperatures compared to 5W30. Simply put, this means the oil flows with more resistance inside the engine, requiring the engine to work slightly harder, which naturally leads to a small increase in fuel consumption. According to data I've checked, under normal driving conditions the fuel consumption difference is about 0.1%-0.3% - not huge but definitely present. However, higher viscosity also has advantages, especially in summer or during frequent highway driving, as 5W40 can form a thicker oil film to better protect the engine. If you're driving an older turbocharged car or frequently carrying heavy loads on long trips, the slightly increased fuel consumption is worth it for better engine protection. The final choice should be based on your vehicle's manual and actual needs, since different engine designs have different oil requirements.
