Why You Should Never Let Your Gas Tank Drop Below a Quarter

An unprecedented snowstorm struck the Northeast in October of 2011—you may remember it. The heavy snow of the rare “Halloween nor’easter” brought traffic to a standstill. On some roads, people were unable to move for eight hours or more. The storm also downed power lines, plunging large areas into darkness.

People who were stuck on the road but had a full tank of gas were able to keep warm by running their engines for about 15 minutes every hour. Other drivers, with less than a quarter tank, sometimes ran out of fuel while trying to stay warm. Those who still had a little gas left—even when the gauge read empty—discovered that nearby gas stations couldn’t pump fuel because of power outages. Gas stations require electricity to operate their pumps; without it, there’s no fuel.

This real-life scenario underscores the importance of always keeping your gas tank at least a quarter full. Along with helping you stay warm during a roadway emergency, it provides a buffer when fuel availability is disrupted. And that’s not all. There are other important reasons to avoid letting your gas tank run too low. Here are six of them:

Keeping the fuel pump cool

Modern fuel pumps are often located inside the gas tank, where gasoline keeps them cool and lubricated. Running low on fuel can cause the pump to overheat, which shortens its lifespan. Loss of lubrication can further damage the pump. Fuel pump replacement can cost hundreds of dollars, and a failed pump can leave you stranded on the road.

Avoiding sediment buildup

When fuel levels get low, the pump is more likely to pick up sediment that accumulates at the bottom of the fuel tank. This can clog fuel filters, resulting in rough running or preventing the engine from starting. Over time, it can also shorten the lifespan of fuel system components. 

Preventing water in the tank

Low fuel levels leave more space in the gas tank, which can allow humid air to enter. If this moisture condenses, water can form in the gas tank. Water in the fuel system can cause a variety of problems, including promoting rust in metal tanks, contaminating fuel in a way that causes rough running, and damaging fuel system components.

Planning properly for long trips

Keeping your gas tank at least quarter full is usually sufficient for daily driving. But when traveling, many drivers prefer to refuel when the tank is half full. This ensures a good fuel reserve in case of emergencies. A half tank in most cars provides 150 to 200 miles of travel, or more.

Protecting diesel fuel systems

If you drive a diesel, never run your tank dry. Doing so allows air to enter the fuel system. Before restarting, this air must be purged, and the fuel pump may need priming. This process can be labor-intensive and costly.

Avoiding overfilling your tank

Overfilling your gas tank can be just as problematic as running it low. You’ve probably seen this scenario at a self-service station: A driver pumps gasoline until the automatic shutoff stops the flow, and then he keeps trying to add more by repeatedly squeezing the nozzle. Each time, fuel flows for a second or two before automatically shutting off again because the tank is full. Unfortunately, this can damage the evaporative emissions system, leading to drivability problems and expensive repairs.

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Keeping your gas tank at least quarter full is a smart habit that can help protect your vehicle, reduce repair costs, and ensure your safety when conditions or circumstances take an unexpected turn.