What Happens if You Put Sugar in a Gas Tank?

We’ve all heard horror stories about someone whose car got vandalized with a bit of sugar in the gas tank. To hear some people tell it, putting sugar in a gas tank will do almost as much damage to the car as running it into a tree would! But what’s the truth; what will putting sugar in a gas tank really do to your car?

If you put sugar into your gas tank, it probably won’t do much to harm your car right away. Gasoline is a refined liquid made up of only single bonds between atoms. The sugar you put in your tank has multiple bonds between atoms and is not as easily broken down.

This blog will explain why sugar doesn’t do as much harm to your engine as most people seem to think. It will also outline precisely what you can and can’t add to your fuel mixture and how these different things could affect your car’s performance. Keep reading to learn more.

Putting sugar into gas tank.

What Happens When You Mix Sugar and Gasoline?

The first thing that you need to realize is that gasoline is a hydrocarbon. It’s made up of carbon and hydrogen atoms. Sugar is also a hydrocarbon — it’s made up of carbon, hydrogen and oxygen atoms. So at a basic level, gasoline and sugar are very similar.

When you mix sugar with gasoline, it doesn’t affect the gasoline. Gasoline is refined to contain only molecules with a single carbon-to-oxygen bond. Sugar has multiple bonds between its atoms — both carbon-to-oxygen bonds and carbon-to-carbon bonds which can’t be broken apart easily.

You probably learned in high school chemistry class that double and triple bonds are more robust than single bonds, so the sugar can’t break apart into individual molecules as quickly as it would in gas form (single carbons with single bonds).

The Difference Between Sugar and Gasoline

Sugar is a food item, not a chemical. It does have multiple carbon-to-carbon bonds and can exist as individual molecules in some aqueous solutions.

However, gasoline is a hydrocarbon — it’s a single molecule. The bonds are so tightly packed together that sugar molecules cannot separate from the gasoline to form a solution.

Here’s a video by Donut Media where they show what happens when you try to mix fuel and sugar:

Things That Dissolve in Fuel

Gasoline is already treated with detergents meant to dissolve any potential contaminants before entering your vehicle’s fuel system.

Dirt or sugar that enters your gas tank is likely to settle at the bottom of the tank. So adding anything else could have no effect other than harming your fuel injectors.

Anything other than gasoline or diesel can damage your engine’s fuel injection system and reduce its efficiency over time, depending on what the substance is.

Why Things Don’t Dissolve in Gasoline

Most gasoline is a blend of two hydrocarbon molecules—paraffin and olefins.

Paraffin is easier to ignite and produces a hotter flame as it burns, making it ideal for gasoline engines.

Olefins don’t burn quite as well but have superior lubricating properties. As a result, most gasoline contains anywhere from 5% to 10% olefin molecules.

Both paraffin and olefin molecules contain carbon-to-carbon bonds of a simple construct. Any other additive will not be able to be broken down when left in a mixture of fuel.

Will My Car Stop Working if It Has Sugar in the Gas Tank?

Sugar in the gas tank is a well-known urban legend. The idea is that if you put sugar in your car’s gas tank, it will cause your engine to seize up.

Your car probably won’t stop working if you spill sugar into the gas tank. While it might not be ideal for the engine, it shouldn’t outright seize. That would happen only if you put the sugar into the gas tank and then didn’t start the engine again for several months or years.

It also depends on whether your car is a carbureted or fuel injected vehicle, as carbureted vehicles are more likely to have problems.

Also, putting sugar in the gas tank of older vehicles with external fuel filters might affect the car. This is because the sugar will block up the fuel system. Sugar acts as a solid and will gum up the small passages in the carburetor. The impurities in the sugar will also clog the jets and needle valves.

In this case, you would need to replace the filter regularly or remove the car’s gas tank to clean it.

What Happens if You Leave Sugar in the Gas Tank for a Long Time?

It is not a good idea to pour sugar into a gasoline tank. The sugar won’t break down, which means it won’t be burned in the engine. Instead, the sugar will settle on the bottom of the gas tank and plug up the fuel line.

If you put sugar into your car’s gas tank, the car will still generally run, although some vehicles may start but run rough. You may be able to drive it for a while, but eventually, you’re going to need to pull over or get towed.

If equipped with one, the fuel injection system may not allow enough air into the engine for it to keep running, so you could end up with a dead engine as well. The metal parts in the fuel system become coated with corrosion from the sugar stuck in them.

This will cause them to wear out more quickly than usual. Sometimes, this damage cannot be repaired, and even if it can be, it will eventually cost you more money in repairs.

How Long It Takes Sugar to Damage the Engine

The amount of time it takes for a car to cease working after being filled with sugar depends on many factors, including how much sugar was added and how long the car ran after being filled with the sweet substance.

In most cases, however, the effects will not be felt until the car is used for an extended period or if the vehicle was left stationary with the sugar in the gas tank for quite some time.

The Effect of Sugar on Fuel Filters

Sugar is a significant problem for fuel filters and causes a reaction with the plastic, resulting in it being clogged or damaged and most probably needing to be replaced.

When you put sugar in your gas tank, it will probably clog your fuel filter faster than if you had just let the sediment build up naturally.

In a fuel filter, sugar will stick to the surface of the filter element and provide a breeding ground for microbes. As they grow, they will clog the pores in the filter media until they can no longer remove contaminants from the fuel. This will eventually starve the engine of energy and cause it to stall or run poorly.

How Much Sugar Will Clog My Fuel Filter?

Sugar and similar products can cause the fuel filter to plug. As a result, fuel cannot reach the engine, and it stalls.

The exact amount of sugar required to clog a fuel filter is not known but would be dependent on many factors such as fuel type (petrol, diesel or others), how much sugar has been added, and the number of miles driven by the car after that.

The ability of a substance to clog a fuel filter will depend on its chemical structure. This can be calculated using density functional theory (DFT). In brief, DFT uses quantum mechanical principles to predict molecules’ structure and thermodynamic behavior.

The Effect of Sugar on Injectors or Carburetors

In the old days of carburetor-equipped engines, so much gas was sprayed into the air intake that it didn’t matter if there were a few granules of sugar mixed in with the gasoline.

The carburetor would just spray it into the air intake along with everything else, and you would be none the wiser.

Today, however, most vehicles are fuel injected, so there isn’t as much gas sprayed into the air intake to mix with everything else.

On top of this, newer vehicles are designed to run on less fuel than older cars. As a result, the mixture of gasoline and air has to be carefully calculated by computers inside the engine itself.

If your vehicle is brand new, the chances are excellent that you have an onboard computer adjusting the mixture all the time to make sure that it’s just suitable for your engine’s needs.


Gasoline and sugar are similar substances, but in many ways, they’re also very different. Like oil and water, the atoms can’t break apart and stay separated.

Gasoline is a refined liquid made up of only single bonds between atoms so that you won’t find any carbohydrate chains inside. Sugar (sucrose) is a carbohydrate that doesn’t dissolve in gasoline easily.

Putting sugar into your car’s gas tank may not cause the atomic bomb of damages that many people claim it will, but it’s still not good for your vehicle, and you should avoid it at all costs.




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