Latest News
Volvo: Safety Beyond the Star Ratings5 Simple Reasons to Keep Your Gas Tank Full
Running on fumes? From optimal maintenance to worst case scenarios, we offer 5 good reasons to keep your gas tank full.
Why Should You Keep a Full Tank of Gas?
Most of us operate under the same basic, immutable laws of the dashboard. The traction control indicator flashing? Stop pressing your luck cornering in the rain in your Toyota MR2. Tire pressure is low? Pull over and break out that can of fix-a-flat for the third time in two weeks. The check engine light comes on? Dissolve into sheer panic and respond by covering the light with a bit of electrical tape.
One light that will mercilessly punish that kind of willful ignorance and benign neglect is your low fuel gauge. Sure, you could continue to operate from quarter tank to quarter tank, only fueling all the way up for that road trip to the McMillen’s bi-annual pickleball tournament in Poughkeepsie. But it turns out perpetually keeping your tank at bare minimum can run you into serious trouble, and getting stranded by the roadside isn’t the only risk you’re running when you’re running on fumes.
Below are five reasons why topping off your tank should be added to your list of car maintenance priorities.
1. Reduce Mechanical Issues
Gasoline not only fuels the vehicle, but it also functions as a coolant for the electric fuel pump motor. In modern cars, this pump sits in the middle of the gas tank filled with cool gasoline. A near-empty tank can cause the fuel pump to work harder and heat up, increasing wear to the pump.
Each time you neglect pumping gas, gunk from the bottom of the fuel tank can get caught in various components of the vehicle. Sediment in your tank can foul the fuel filter. If the fuel filter doesn’t catch the sediment, you run the risk of clogging a fuel injector. This is less of an issue today with modern heavy-duty plastic fuel tanks, but in older vehicles with metal fuel tanks, particulate rust can be a problem.
When a diesel runs dry, the injector pump fills with air and the vehicle won’t start by simply adding more diesel fuel. A tow truck and mechanic may need to get involved to tow the vehicle, remove filters, pressure-blow the fuel lines before adding fuel and priming the engine. Because of this, maintaining a full tank with a diesel engine is even more critical than with a gasoline engine. Thankfully, most diesel fuel indicators account for this and show empty even with some fuel left in the tank.
The most common concern with low fuel arrives once the mercury dips below freezing. That’s when condensation built up in your half-empty fuel tank has a greater chance to get sucked into the fuel lines and freeze. Not only can this mean your vehicle won’t start (with frozen water blocking the flow of fuel to the engine) but the lines themselves may become damaged by the expansion and contraction of the freezing water.
2. Improve Gas Mileage
Some will argue that because the gas tank is lighter when it’s low, a low tank will give the car greater fuel efficiency. A lighter load does require less gasoline, but the weight of a full fuel tank compared to a partially full tank is not all that significant. A gallon of gasoline weighs 6.3 lbs. (for reference milk weighs 8.6 lbs. per gallon), so even in large vehicles the total weight of a full tank is less than 250 lbs., and your average commuter is trucking around between 14 to 16 gallons or roughly 100 lbs. of gas. And in real life scenarios where you’re never driving with a truly empty tank, we’re talking about a difference in weight of more like 50 to 75 percent (half to one quarter full). So, unless you’re already stripping out the back seats, door cards, and the air conditioner to save weight, a full versus a partial tank of gas shouldn’t be a top concern when it comes to fuel efficiency.
3. Stay Safe on the Road
Running out of fuel completely is one of the biggest car maintenance self-owns. You saw the red indicator. It’s been screaming at you for two days now. Just a few more miles you say. Just one more freeway exit before we pull off. And then you find yourself losing power in heavy, rush hour traffic.
Being stuck by the roadside is bad enough in mild weather, but in sub-zero winter weather or scorching summer conditions, it’s downright dangerous. Even a quarter tank is going to be problematic when you need, really need your climate control working. This is relevant even if you’re not silly enough to let your car run out of gas. A flat tire or other mechanical breakdown can turn from an inconvenience to a much more serious situation if you’re also low on gas in severe weather.
Speaking of which, along with keeping the fuel tank full, it’s a good idea to have a weather appropriate vehicle emergency kit.
4. Save Yourself Time
Some of you might only be allowing your fuel to flirt with E because you struggle finding time to fill up. Procrastination can turn that inconvenience of five minutes at the pump into a major detour to your day if you run out of gas. That’s why we recommend taking those little opportunities throughout the week to fill up or top off your vehicle. By making frequent fill-ups a higher priority you’ll avoid last-minute emergencies.
5. Save Yourself Money
Skimping on fueling up doesn’t save money and could lead to expensive repairs and/or a costly tow job. Habitually running the car to empty could lead to fuel pump damage, a repair potentially costing hundreds or even thousands in parts and labor. Filling up can be painful when prices are high, but it is an investment that can protect your vehicle and save you time and money down the road.
Trying to save money while driving? The tires are a great place to start. How to save money by maintaining your tires.
Editor’s Note: This post was originally published in January 2020 and has been completely revamped and updated for accuracy and comprehensiveness.
How far can you run a 2000 volkswagon beetle low on fuel?
Hey Kevin, it depends how low on fuel exactly!
It’s interesting how cars may actually be less efficient when low on fuel due to the potential for evaporation. I just purchased a diesel lawn mower last month, so I need to order some fuel for it before the weather warms up. I will be sure to keep it topped off throughout the summer to maximize efficiency.
Thanks for sharing!
It is said that if it is full tank that the fuel consumption is very efficient or fuel consumed somewhat slowly. Is this true or a myth?
Thanks.
Hi there! As far as we’re concerned, that is a myth!
Great post, thanks for sharing. Picked up some good and valuable insight
Thanks for checking it out!
This blog happens to be one of the best blog analyzing on 5 simple reasons to keep your gas tank full. It is just a proper critique blog, would suggest others it as well.
Thank you, we appreciate this so much!
Is it ok to fill up my gas tank as soon as the handle pops?
We like to say, “If the handle pops, you must stop.” There’s a reason it does that. Overfilling can affect the charcoal canister and possibly create longer term issues.
A couple quick counterpoints:
1) on fuel evaporation … since the late-1970s/early-1980s, vehicles have been equipped with non-vented fuel systems that include an evaporative emissions control system (usually abbreviated as simply “EVAP”) designed to keep fuel from evaporating to the outside air. Any fuel that does evaporate would be ingested into the engine via the EVAP system courtesy of the engine’s own vacuum, so fuel that evaporated within the tank wouldn’t be lost or wasted — it gets burned, just like normal. So the evaporation problem is a myth.
2) cooling effect on in-take fuel pumps … while it’s true that the fuel pump would be kept marginally cooler while submerged in fuel, many/most in-tank fuel pumps are mounted high up on the sending unit, to allow room for fuel straining sock/filter and the float assembly. As a result, once the fuel level reaches 3/4 or 1/2 tank, the fuel pump is generally exposed anyway. But that’s ok, because electric fuel pumps tend to receive ample cooling from the fuel flowing through them. Keeping them submerged isn’t strictly necessary. They’re located in the tank because most electric pumps work better as “pusher” pumps, rather than as “puller” pumps.
3) low fuel level causing evaporation … sure, as the fuel level decreases, the remaining volume is filled with air, which could allow for evaporation, but as I pointed out in point 1, evaporation isn’t a problem in modern cars, because the systems are closed systems. Any fuel that evaporates will either be burned by the engine anyway, or when eventually fall out of suspension in the air within the system as liquid fuel again as the temperature cools down. Besides, a bigger concern than low fuel level would be how the fuel gets aerated as it returns to the tank via the return line. As the returning fuel reaches the fuel tank, it’s either allowed to squirt back onto the fuel in the tank, which would have a similar effect to running your kitchen faucet into a pan — it creates lots of bubbles — or it could be introduced lowed in the tank, perhaps beneath the surface of the fuel, but it still contains plenty of air/bubbles because the return side of the fuel system isn’t fully pressurized. Regardless, aerated fuel isn’t really a problem nor is any evaporation caused by it, because (again) the system is closed and doesn’t allow the fuel to escape, except through the EVAP system or via the pressurized fuel line to the engine, and in either case, the fuel just gets burned like usual.
4) Weight … 250 additional pounds shouldn’t be considered significant? That’s more than the weight of an average adult … even overweight Americans. And since most cars and light-duty (1/2-ton) pickups and vans only have about a 1000 pound “cargo” capacity (including passengers and the driver), that’s the equivalent of 1/4 of the car’s cargo capacity. Sounds pretty “significant” to me. That extra 250 pounds will require the engine to make more power to get it moving, and that means it’ll have to burn more fuel. Will the difference be dramatic? Probably not. But to call 250 pounds “not significant” is disingenuous.
Thanks for your input, Jason! We love that you joined the conversation!
How do you bleed a seat 1.6 TDI 2013 when it runs out of fuel
I agree with other others: Great post, I picked up some good and valuable insight. I also like some other peoples’ replies that go into more detail. I am 70+ and grew up with 1960’s cars (I have 56 Tbird) and I (unfortunately) think I know ‘enuf’ to get by from high school days.
Sidebar: Unrelated to this article, I painfully discovered why my self-installed Pertronix ignition acted so haphazard on my rebuilt Tbird, 312 motor (and downright ‘destructive backfiring plus run-on’) to my newly resprayed engine bay and rebuilt engine: poor grounding of regulator. The mechanic overlooked cleaning/chasing the regulator mounting holes for paint removal to insure good grounding. Indeed, there is even a small ground strap for the regulator, but as described that hole and strap surface were never properly prepared.