Why you shouldn't fill your gas tank while the car is running? (2023)

Is it bad to fill your tank when your car is on?

The reason is simple: Directing gas into a fuel tank while a car is running is harmless, provided that there isn't a spark nearby. Indeed, watch a NASCAR or Formula 1 race, and that is exactly how pit crews refuel — with the race car running.

The issue isn't the running car itself, but rather it's the conditions that can be created. When you fuel a car with the engine on, it increases the chances of gas vapors coming in contact with heat or electricity. When that happens, ignition can result.

Gas topping damages your car.

Overfilling the gas tank can cause liquid gas to enter the charcoal canister, or carbon filter, which is designed only for vapor. Gas in the system can affect your car's performance by causing it to run poorly, and damage the engine, he says.

Although the possibility is slim, pumping gas while your car is running can still lead to a flash fire. Gasoline is a highly explosive liquid that exudes dangerous expanding vapors. Pumping gas with the vehicle on can increase the risk of these vapors coming into contact with heat or electricity, resulting in a fire.

Don't Leave the Engine Running

Make sure you put your vehicle in park and turn the engine off before pumping gas. You should also switch off any auxiliary 12-volt power sources such as phone chargers and cigarette lighters because, while rare, they can be a potential igniter of a fuel fire.

Your exhaust system produces emissions into the air and contributes to air pollution. Sitting in one spot for a long period of time pollutes air. Decreases performance. Over time, idling can cause your head gasket, spark plugs, or cylinder rings to deteriorate and stop working.

Idling wastes fuel – and money. Vehicles get ZERO miles-per-gallon while idling. Larger vehicles tend to waste more fuel than smaller ones. Idling can also cause greater engine wear-and-tear over time, resulting in higher maintenance costs.

It is recommended that you refill the tank once it is a quarter full. That allows you to leverage gas mileage since the vehicle is lighter with a partially filled tank. The pump will also be pumping cleaner gas.

The bottom line is that topping off your car is dangerous to you and your car, and may cause problems. Your best bet is to stop pumping when the fuel pump clicks off.

If watching out for your fuel line and gas tank weren't enough, your fuel pump could also become affected if you don't keep the tank topped off. When you run low on gas, your fuel pump can begin sucking in air. This can cause the pump to heat up to a dangerous level or fail over time, resulting in expensive repairs.

Is it better to fill your car up?

Extra moisture in a tank can cause rust from the inside out and water is a harbours harmful contaminants so less water is better. Keeping a full tank of fuel enables you to track mileage and fuel costs. You won't lose as much fuel; empty space in the tank causes evaporation through the tank's ventilation system.

Is it safe to sleep in a car with the engine running? No, it's not safe to sleep in your car with the engine running. Leaving your car engine turned on while sleeping could lead to dangerous exhaust fumes containing carbon monoxide entering the vehicle.

You see signs at gas stations that say no cell phones. Here's the deal: Cell phone batteries can explode, which would be a real danger if that happens while you're pumping gas. What you need to be concerned about is static electricity.

According to Family Handyman, leaving the engine running increases the chance of gas vapors igniting if they come in contact with static electricity. There is a very minimal chance of a fire occurring because of this, but it is possible. In short, if the fumes burn instead of the liquid, it could lead to an explosion.

So, overfilling your tank sends excessive fuel into the charcoal canister or carbon filter which is strictly designed for vapor only. When fuel gets into this system, it will affect your vehicle's performance and could damage the engine meaning hefty repair costs.

Something else to keep in mind is that topping off your tank could cause gas to spill on the ground, which is a safety and environmental hazard. The bottom line is that topping off your car is dangerous to you and your car, and may cause problems. Your best bet is to stop pumping when the fuel pump clicks off.

Filling up a tank halfway compared to a full tank of fuel only reduces the weight by 2.5%. At this level it is likely to make very little difference on the vehicle fuel economy. We suggest if your drivers are regularly driving to advise them to fill the tank all the way to the top when they visit a petrol station.

You should always fill your gas tank full rather than adding $10 - $20 at a time. The answer is True! You should definitely fill your tank when you stop to fuel up at the gas station.

Premium gas has a higher resistance to engine knock in luxury and performance vehicles with turbochargers or high-compression engines, so you can hit that horsepower smoothly. Additionally, premium gas can increase fuel efficiency, potentially bringing better gas mileage for longer while decreasing emissions.

No matter what you've heard, premium-grade gasoline won't do more to clean deposits from your fuel injectors or other parts of the fuel system because today's regular gas contains the same detergent additives. The main difference with premium is its octane rating — 91 or higher compared with 87 for regular octane.

What happens if you mix regular gas with premium?

Can I mix premium and unleaded gas? Yes, drivers can mix the two types of fuel. The combined gas types will result in an octane level somewhere in the middle — something the vehicle “will survive,” according to The Drive.

Experts recommend you let it warm up before driving it. They say this helps get the fluids properly flowing. Auto professionals also say it's a good idea to invest in a frost plug heater. This tool helps warm up the engine and prevent fluids from freezing.

Usually, a car does not need to be warmed up, even in cool weather. However, if the temperature is below freezing (or up to 40 degrees F), allowing the car to run for about 30 seconds is plenty to get things going.

Don't Wait Until You're On E Before Filling Up

Driving around with an almost empty tank makes the remaining gas evaporate more quickly. Fill your tank whenever it drops below half-full for optimal fuel efficiency.

Bigger is better

Filling both tanks means an awful lot more fuel is carried around, and hence a more pronounced saving. Assuming an average speed of 40kmh, you would save nearly 14 minutes by filling up half as much, twice as often.

That's because gasoline, like all liquids, expands when heated. So, according to this advice, gasoline will be denser in the cool of early morning, meaning you'll get more energy per gallon than later in the day.

Ideally, store your car in a climate-controlled facility. Fill the gas tank completely full. An empty or low gas tank will lead to internal rust as condensation and moisture builds within the tank.

The Best Day To Buy Gas: Monday

These findings come as no surprise — Monday was the most reasonable gas price day found in GasBuddy's 2017, 2018 and 2019 studies, as well. However, report findings revealed that Friday, routinely one of the most expensive days to purchase gas, is now one of the cheapest.