Why can a 70-liter fuel tank hold 80 liters?
2 Answers
The reason a 70-liter fuel tank can hold 80 liters is due to the volatility and expansibility of gasoline. The functions of engine oil include the following 3 points: 1. Lubrication: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing bush. To prevent excessive wear of parts, an oil film needs to be established between the two sliding surfaces. A sufficiently thick oil film separates the surfaces of relatively sliding parts, thereby achieving the goal of reducing wear; 2. Auxiliary cooling: Engine oil has a relatively low specific heat capacity and is located inside the engine, so it does not inherently have a cooling effect. However, during engine operation, the heat generated by fuel combustion can be carried back to the oil tank by the engine oil and then dissipated into the air, assisting the radiator in cooling the engine. The actual cooling effect is provided by the water outside the engine casing; 3. Sealing and leak prevention: Engine oil can form a sealing ring between the piston rings and the piston, reducing gas leakage and preventing the entry of external contaminants.
Last time I went to refuel, I encountered a similar situation. My car's fuel tank is labeled as 70 liters, but it took 78 liters, which seemed odd. The gas station attendant explained that the nominal tank capacity isn't the maximum volume, but rather the safe design capacity. The standard practice is to leave a 10-15% margin to prevent issues from fuel expansion and contraction due to temperature changes, such as fuel expanding and potentially overflowing in summer when temperatures rise. When refueling, if the fuel temperature is low, like in winter, the higher density allows more liters to be filled. Conversely, in hot weather, you should add less to prevent overflow, which could damage fuel lines or pose safety hazards. It's recommended to stop refueling when the pump automatically shuts off and avoid overfilling. Also, remember to check if the fuel tank label is accurate, as some car factory labels may be outdated or not updated after repairs. Regular maintenance can avoid such surprises, ensuring safe and cost-effective driving.
