Q: How full should I keep my gas tank?

asked by on November 24, 2015

How full should I keep my gas tank?

Check Fuel Cap light is on Inspection $79.99 - $99.99 Get a Quote

In my opinion, you should keep your tank at least half full at all times. This is not for any mechanical reasons but more for personal safety reasons. If you treat the halfway mark as if that were the empty mark, then when an unforeseen event happens you will have a cushion of fuel. Emergencies happen without warning and the security this provides will bring peace of mind. In foul weather you could become stranded on the highway and run out of fuel. In extreme weather this can pose a threat to your health. A fuel or gas gauge is not exact and cannot guarantee how many miles are actually left until the tank is empty. Some people think that there are still many more miles left once the gauge is at E, while others swear that once the Low Level Light is on, if they don’t get fuel they may run out before they get to the next station. A vehicle breaking down cannot usually be avoided since parts can break or fail without warning, but you can avoid damage or the inconvenience of running out of fuel if you simply keep the tank filled.

From a mechanical point of view, modern vehicles have evaporative emissions systems to prevent fuel vapor leaks from the tank. In order to test these systems, criteria need to be met before the test can be performed. Many of these systems have temperature and level requirements in order to run the self diagnostic check of the system. You may have heard someone complain that the Check Engine Light came on in their car after getting gas due to a loose cap. This emissions monitor system generally requires the tank to be anywhere between 15 to 80 percent full in order to run the self diagnosis test properly. If the tank is constantly topped off or left empty, these tests may fail to run. For your convenience, safety and for the onboard monitor systems, keep your tank full.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

My Hyundai Elantrav2005 check engine light on. Sometimes shakes in idle Drive and hesitants over 40mph switching into 4th gear

There are more than three dozen ignition and fuel system components and sensors that could be the cause of the warning light and idle issues you're experiencing. In order to determine which is the culprit, it's best to start by...

My gas cap light keeps coming on. It won't click when I turn it, so I bought a new cap. New cap won't click closed either. What co

If you need a gas cap, especially if you are trying to resolve what you believe might be a cap related fault, use an OEM (dealer supplied) cap. Using a genuine OEM cap of the design supplied when the car...

An inconsistent starter motor that occasionally works perfectly now will not work. Then engine will not crank at all.

Hi there. It is possible for the starter to fail. But before replacing the starter, make sure that the battery cables are tight and clean. Then check the starter relay and make sure that the relay is clicking. If the...

Po420 bank1

Hello Tom. P0420 is the Catalyst System Efficiency Below Threshold (Bank 1) code. While there are a multitude of components that can cause this code, the general concept is that your catalytic converter is not working properly. If you suspect...

Key fob won't unlock all 4 doors. Only the drivers door

Hi there. Is this a smart key or a physical key and wireless fob? Do the other door locks work when the lock switch on the driver's door is operated? Have you tried pressing the unlock button 2 times quickly...

My engine is overheating and cold air is coming from the vents.

Engine coolant circulates through the heater core located behind the dash to provide heat. If coolant is not circulating properly, hot coolant will not flow into the heater core. Possible causes are a water pump that is not spinning properly...

Brake booster signal failure

It is possible that your master cylinder may be failing on your 2014 Dodge Dart. The master cylinder can be full and still cause issues. If the internal seals inside the master cylinder begin to fail, they will allow brake...

How do I fast forward or rewind with the iPod?

When listening to a track on the iPod, you can easily fast forward or rewind. Press and hold the Up or Right button (depending on your model) for more than 1.5 seconds to fast forward, or press and hold the...

Related articles

Does Buying Good Quality Gas Matter?
Gasoline Gasoline is refined from crude oil and can contain impurities and minor inconsistencies. Because of this, it is standard practice for additives to be mixed into gas. This means that one person can fill up their car anywhere and...
What Is E85 Ethanol?
E85 E85 ethanol is a fuel that can be used to power internal-combustion engines. Some vehicles can use E85 and gasoline, while others are tuned for E85 only. E85 is named as such because it is 85% alcohol. The other...
When Does the Gas Light Turn On in My Car?
Going Going to the gas station is a chore and many of us wait until the gas light is on and the tank is nearly empty. But waiting until your fuel tank dries up is a bad habit, and the...