Fact vs. Myth: What Does Sugar in a Gas Tank Really Do?

Stop us if you’ve heard this one—if someone poured sugar into a gas tank, then it’ll cause all sorts of mechanical maladies and ultimately render the vehicle kaput.

Allegedly, the sugar is supposed to chemically react with the gasoline and transform into a gooey, semi-solid sludge that completely clogs up the gas tank, fuel lines, etc.

The sensational nature of this commonly-perpetuated rumor has caused it to be passed around for decades. Is there any truth to this age-old rumor?

Let’s find out!

Here’s what would happen if sugar was poured into a gas tank

Four different types of sugar arranged in mounds.
Four types of sugar | Romain Behar via Wikipedia

The truth is that sugar doesn’t dissolve in gasoline as it does in water. If sugar was poured into a gas tank, then the sugar crystals would simply sink to the bottom of the tank, just as sand would.

Eventually, all of that sweet stuff floating around in the gas tank would probably clog up the fuel filter according to Popular Mechanics. It could cause the engine to randomly hesitate or misfire.

However, there’s another substance that could easily disable a vehicle when poured into the gas tank…

Water and gasoline=bad news

A water droplet falling into a body of water.
Water: The natural enemy of your gas tank | Pixabay via Pexels

That’s right—a sufficient amount of water can cause some serious damage to a vehicle when poured into the gas tank.


Gasoline floats on top of the water, so if you pour a few cups of water into the gas tank, the fuel pump will flood the fuel lines with water instead of fuel, causing your engine to buck, stall, or simply refuse to start.

If your ride happens to be the unlucky recipient, don’t fret—there are ways to remove that water from your gas tank.

Removing water from a gas tank

A mechanic inspects the undercarriage of a car.
Mechanic inspecting a car | Malte luk via Pexels

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If there’s only a little bit of water sloshing around in your vehicle’s gas tank, you can use a fuel additive that dries up water in your tank. The additive gloms onto the water molecules as it goes through the running engine, eventually removing the water from your tank.

If there’s a significant amount of water present in your ride’s gas tank, then you should take your vehicle to a mechanic so they can drain it. The mechanic may remove the gas tank from your vehicle, drain the contaminated fuel, and install new fuel filters. Then, the mechanic will reinstall the fuel tank and fill it up with fresh, water-free gasoline.

Sugar in the gas tank: Myth debunked

So there you have it—sugar isn’t the worse thing that can happen to your gas tank. Still, it’s one more thing you shouldn’t have to deal with.