At the Pump: Does Driving Low on Gas Hurt My Car?

Low fuel
Low fuel | Micah Wright/Autos Cheat Sheet

Getting to know your car boils down to analyzing a vehicle’s limitations and determining what lines not to cross. Just like its human occupants, every vehicle has its strengths and weaknesses, and even though some cars aren’t exactly Fort Knox straight from the assembly line, the majority of modern automobiles are pretty spectacular.

But not every vehicle on the road today is brand spanking new and indestructible. A lot of us are forced to drive older cars, ones in which we find all sorts of issues, as Father Time’s hand slowly shoves them closer to the scrap heap. It’s an inevitable fate for almost every car, regardless of how well made it may be, a fact that gives great weight to the importance of proper maintenance.

Fuel price
Fuel price | Joshua Lott/Getty Images

So when the risks of running a car on low levels of fuel came up in conversation the other day, I was moved to action. While it may not be the worst thing someone could do to their car, it is by no means a good thing either. Fuel systems are a finicky and dangerous thing to play with, and every mechanic I’ve ever talked to has agreed that running around town on fumes is only going to shorten the lifespan of your ride all the more.

According to a report Consumer Reports did on the subject, driving with little to nothing in the tank can take a heavy toll on your car. It’s not just the lack of liquid back there you have to worry about: Consumer Reports Auto Test Center shop supervisor and certified mechanic John Ibbotson says that, “While the cases are rare, there is real potential of a costly mechanical problem.” In fact, I’ve seen it happen firsthand. Several times.

Gas station
Gas station | Justin Sullivan/Getty Images

Gasoline doesn’t just serve a purpose as a combustible product; it also acts like a coolant for the electric fuel-pump motor. So when your tank runs low, this forces the pump to suck in increasingly large amounts of air, creating excess heat that can cause the fuel pump to fail prematurely. Sucking in fumes instead of fuel will also cause your engine to run lean, and after continued exposure, can cause all sorts of engine heat issues.

Another problem is that fuel tanks tend to grow contaminated over time, as things like water deposits, metal corrosion, and other impurities cake onto the inside of the tank and slosh around. Remember, fuel gets pulled from the bottom, not the top, so running low on gas means all that flotsam could get sucked up if it drops too low. All of that grime doesn’t do your fuel system any favors, and could lead to a clogged filter, a choked fuel pump, or gunked-up injectors, all of which cost much more to fix than a full tank of gas.

Here are a few tips for keeping that fuel system up to snuff, and if you want to outsmart the pump and get the most out of every fill-up, check out our article on five gasoline cheats for the average driver.

  • Keep your tank more than ¼ full to prevent air and gunk from sucking into the system.
  • Plan ahead, and fill up when you aren’t busy. This way if you get stuck in traffic the next day, you aren’t panicking.
  • Don’t trust that fuel range minder. Those numbers are about as reliable as Dick Cheney’s aim on a hunting trip, and it all depends on how you drive.
  • If you see a tanker truck refilling a gas station, avoid it. If you think your tank is dirty, imagine all the crud that semi is stirring up as it dumps countless gallons into the ground.
  • Use high-grade system cleaners, and when in doubt, change that fuel filter. These small maintenance upgrades will only help you out in the long run.