How full do I need to keep the fuel tank at any given time?
While some people don't give much thought to how empty their fuel tank is or how much they fill their tank when refueling, others are convinced that there is some magical fuel level that will keep the fuel pump running forever. Some stick to the quarter rule, while others say it takes at least half a tank at any given time. Is there a correct answer?
Why does fuel level matter?
The fuel pump, which is responsible for pumping fuel from the tank, can generate heat during prolonged operation. Most fuel pumps are designed to be cooled by the fuel in the tank acting as coolant. If there is not a lot of fuel, then the fuel pump may heat up more than it should, which will shorten its life.
When the fuel tank is empty, air will replace the used fuel. The air usually contains at least some water vapor, and the combination of air and water causes corrosion inside metal gas tanks. Debris from this rust will settle to the bottom of the tank, and if the fuel tank is run dry, the debris will enter the fuel system. Most modern cars don't have this problem because they don't use metal fuel tanks. The fuel still sometimes contains contaminants that settle to the bottom of the tank, and these can become agitated and sucked into the fuel pump if the tank is empty.
Optimal fuel level:
For short trips and regular commuting, it is recommended to keep the gas tank at least half full. Ideally, if it is completely filled.
For longer trips, try to keep it above a quarter of a tank and be aware of how far the average distance between gas stations is in the area you are traveling through.
Keep in mind:
Fuel level sensors are not always the best indicator of fuel level. Try to get a feel for how your own car uses fuel and how much fuel you fill each time it shows ¼ or ½ full.
The diesel engine may be damaged due to running out of fuel.
