Many drivers are used to postponing a visit to the gas station until the last possible moment, relying on the red indicator on the dashboard. However, this habit poses serious risks to the technical health of the car, with modern diesel and gasoline systems with direct injection being particularly vulnerable.
The main danger at critically low fuel levels lies in the operation of the fuel pump. This component relies entirely on the fluid passing through it for its lubrication and cooling. Very often, when the level drops below a certain threshold, the pump starts to suck in air, which leads to "dry" operation, followed by rapid overheating and accelerated wear of its mechanical elements.
The problem worsens during dynamic driving. Taking sharp turns, accelerating quickly or driving on steep slopes causes the scarce amount of fuel to splash and shift to one end of the tank. At these moments, the intake mechanism briefly remains dry, interrupting the uniform supply of fuel to the cylinders and subjecting the entire unit to thermal and mechanical shock.
An additional risk factor is the accumulation of condensation and sediment. Water droplets form in the empty part of the tank due to temperature differences, which easily freeze and block the fuel lines during the winter months. In addition, microscopic dirt settles at the bottom over time, which, when the tank is empty, is sucked in and quickly clogs the fuel filter or the nozzles themselves.
To avoid costly repairs, a level below 25% of the tank capacity should be considered critical. A yellow or red indicator on the dashboard is a signal of an emergency, not a prompt to start looking for a gas station. Maintaining at least a quarter of fuel is the simplest and cheapest insurance for the long life of the fuel system.