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What to Put in Gas Tank to Ruin Engine

February 19, 2024 | Victor Lukasso

While using a vehicle, it’s important to take note of harmful substances that could Ruin the Engine when they get into the gas tank.

This should be a warning, especially when leasing your car for occasions and other ceremonies, as people might tend to be careless with other people’s belongings.

It’s also important to note that tampering with a borrowed vehicle’s fuel system can cause serious damage to the engine and other components.

Additionally, intentionally damaging someone else’s property is illegal and can result in criminal charges.


This article is informative and will list substances that will ruin your engine when you put them into your gas tank.

These substances include water, excessive oil, bad fuel, urine, sugar, hydrogen peroxide, salt, soda, brake fluids, and bleach.

Continue reading as we explore how these substances threaten your engine and how to maintain and care for a vehicle’s fuel system properly.

Things to Put in Gas Tank to Ruin Engine

Here are 10 substances you should be cautious of introducing into your gas tank in no order.

  1. Water
  2. Excessive Oil
  3. Salt
  4. Bad Fuel
  5. Brake Fluid
  6. Soda
  7. Hydrogen peroxide
  8. Bleach
  9. Urine
  10. Sugar

Let’s see how these things affect the engine once it enters the fuel system.

1. Water

What happens when you put water in a gas tank? This query is common among car owners who have mistakenly misplaced water for fuel while refilling their gas tanks.

This can be disastrous since fuel and water don’t mix, leading to increased corrosion and further damage to the fuel injector if not managed on time.

Also, water can get into the fuel system through condensation but in small quantities, which shouldn’t be a cause to worry, but a deliberate act of putting water into the gas tank will damage the engine.

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The car engine might be working fine for some time, but it’ll eventually stop working ad won’t respond to further inputs.

This is because the water in the fuel injector and filters will further spread to other parts of the engine, making combustion impossible.

Some of the symptoms associated with water in a gas tank include;

  • Engine misfiring
  • Rough Idling
  • Illuminated check engine light
  • Unresponsive engine
  • Stalling

To resolve this, you’ll need to seek the help of a mechanic to displace the necessary parts and install a replacement.

2. Excessive Oil

Older vehicles use engines that allow fuel and oil to be mixed. However, engines of modern vehicles could get damaged if excess oil is introduced into the gas tank.

If a small amount of oil gets into the gas tank, it could burn off in the combustion process, but an excess input will damage the car’s piston.

Whichever way, keeping your gas tank free from engine oil is advised because it’ll damage your engine slowly.

If you notice oil in your gas tank, call the attention of a mechanic for the best fixes.

3. Salt

The presence of salt in your gas tank could Ruin your engine. This is because of its corrosive ability.

Once salt gets mixed with fuel, the salt crystals could block fuel filters, leading to engine power loss.

While a small amount of salt might not be insignificant, it’ll cause little damage if they’re retained in your gas tank for a long time.

4. Bad fuel

Purchasing the wrong fuel seems to be the worst situation of them all. Gasoline is considered bad if it has a low hydrocarbon rating.

This often happens when you, fuel stations, or retailers keep fuel for a long time and start selling it without rejuvenating it.

Also, this could be a situation where the fuel gets mixed with water or other substances. Any fuel that has lost its hydrogen-to-carbon bond is considered bad.

Oh well, how do you know a bad fuel? You can tell if the fuel is bad from the small and darker look.

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A bad fuel will block the fuel system and cause engine failure. So, I’ll advise you not to turn on your engine if you’re lucky enough to notice it.

You can check out our article on how to rejuvenate old gasoline and also seek the attention of a mechanic.

Also, remember that not all fuel can be rejuvenated, and you, as the seller, could be charged in court.

5. Brake fluid

Brake fluids are meant for hydraulic components such as brakes and clutches and shouldn’t find their way into the gas tank.

The presence of enough brake fluid in the fuel system can reduce the car’s overall performance and cause damage to other components.

Always ensure you’re putting the brake fluid in the right channel, and always flush your brake fluid once in two years.

6. Soda

In this context, Soda refers to Coca-Cola, sprite, 7up, Pepsi, and other sodium-carbonated drinks.

The presence of these soft drinks in large quantities can damage the engine. One of the notable signs is an increase in smoke output from the exhaust.

So watch out for kids or intruders who might want to introduce soda into your gas tank.

7. Hydrogen Peroxide

While engine peroxide helps boost your car performance, mixing hydrogen peroxide with your fuel is disastrous.

It’ll make your engine run at higher temperatures, causing total damage to your motors and pumps.

8. Bleach

Bleach mixing with fuel isn’t advised because of its corrosive ability. This is possible because of the presence of chlorine in the mixture.

And the bad part is that it destroys the engine silently without the driver’s notice.

If you notice the presence of bleach on time, you can fix it, but if your engine has accrued some damage, it’s not repairable.

9. Urine

The presence of urine in large quantities in your gas tank could also ruin your engine.

Anything other than gas that gets into your gas tank would cause damage to your fuel system, whether large or small.

So, the best way to avoid this is by regularly checking for strange substances in your gas tank and getting rid of them.

10. Sugar

This common household substance is capable of bringing your engine to a wreck. Introducing sugar in large quantities will turn your petroleum sugary and clog up the fuel system.

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Some symptoms accompanying this include stalling, low engine performance, constant fuel pump failure, and hard starting.

Other sugar constituents also make it hard for the engine to survive that hit. However, modern cars come with a fuel system that helps prevent this.

However, I’ll advise you to seek the help of a mechanic for a proper fix.

How to Maintain a Vehicles Fuel System

Here are some guides on properly maintaining and caring for a vehicle’s fuel system.

Use high-quality fuel

It’s always important to use a fuel with a high octane rating, as the auto manufacturer recommends.

Bad fuels can result in reduced performance and efficiency.

Replace the oil filter regularly.

The fuel filter removes contaminants from the fuel before it reaches the engine.

You are advised to replace the fuel filter regularly to ensure the fuel system is free from dirt, debris, and other contaminants.

Keep the fuel tank full.

It is generally recommended to keep the fuel tank at least half full to prevent moisture from accumulating in the tank.

Moisture can cause rust and corrosion, which can lead to problems with the fuel system.


What will damage a gas tank?

Several factors can damage a gas tank: corrosion, impact by external forces, adding foreign substances to the gas tank, and poor maintenance will damage a gas tank.

Will bleach in a gas tank ruin an engine?

Bleach in a gas tank will ruin the engine because of the corrosive ability of the chlorine to mix with the gasoline. This can be prevented if noticed on time.

Can you put Coke in your gas tank?

Auto experts have proven that putting coke in your gas tank will damage your engine.

What’s the worst thing to pour into a gas tank?

The worst things to pour into a gas tank are water, excessive oil, bad fuel, urine, sugar, hydrogen peroxide, salt, coke, brake fluids, and bleach.

Final Words

By following the above tips, you can help ensure your vehicle’s fuel system works smoothly and in perfect condition.

Remember, intentionally damaging your vehicle or someone else’s property is never a good idea. If you are experiencing problems with your fuel system, it is always best to consult a professional mechanic for assistance.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.