Worst Things To Put In A Gas Tank: Common Contaminants And Chemical Additives

Fuel Additives
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Learn about the worst things to put in a gas tank, including water, sugar, bleach, and more. Find out the potential damage caused by household products and non-fuel liquids.

Common Contaminants in Gas Tanks


Water is one of the most common contaminants found in gas tanks. It can enter the tank through condensation, rainwater, or even a faulty fuel pump seal. But why is water in a gas tank a problem? Well, water and gasoline don’t mix. When water enters the fuel system, it can cause a host of issues, such as:

  • Corrosion: Water promotes rust and corrosion in the fuel tank and fuel lines, which can lead to leaks and further damage.
  • Fuel Injector Problems: Water can disrupt the proper functioning of fuel injectors, affecting the fuel-air mixture and leading to poor engine performance.
  • Fuel Line Freeze: In colder climates, water in the gas tank can freeze and block the fuel lines, preventing fuel from reaching the engine.

To prevent water contamination in your gas tank, it’s important to keep your fuel system sealed and protected. Regularly inspecting the fuel pump and ensuring there are no leaks can help prevent water from entering your tank.


You may have heard the urban legend about someone sabotaging a gas tank by pouring sugar into it. While this may sound like the plot of a movie, it’s important to address the myth. The truth is, sugar does not dissolve in gasoline, and it won’t cause any significant damage to your engine if it ends up in the gas tank.

However, sugar can cause problems if it enters the fuel system through the fuel filler neck or vents. It can clog the fuel filter or fuel injectors, leading to engine misfires or stalling. So while sugar may not be a catastrophic contaminant, it’s still best to avoid introducing it into your gas tank.

Sand or Dirt

Sand or dirt in a gas tank may seem like an unlikely scenario, but it can happen in certain situations. For example, if you’re refueling at a construction site or a dusty area, small particles of sand or dirt can accidentally enter the gas tank.

The presence of sand or dirt in the fuel system can lead to various problems, including:

  • Clogged Fuel Filters: Sand or dirt particles can clog the fuel filters, restricting fuel flow and causing engine performance issues.
  • Fuel Pump Damage: Sand or dirt can also damage the fuel pump, leading to fuel delivery problems and potential breakdowns.

To prevent sand or dirt contamination in your gas tank, it’s essential to be cautious when refueling and avoid filling up in dusty or dirty environments. Additionally, regularly replacing fuel filters can help prevent any potential issues caused by these contaminants.

Remember, keeping your gas tank free from common contaminants like water, sugar, and sand/dirt is crucial for maintaining the performance and longevity of your vehicle’s engine. By being aware of these contaminants and taking preventive measures, you can ensure a smooth and trouble-free driving experience.

Chemical Additives and Solvents


Bleach is a common chemical additive that can contaminate gas tanks. It is often used as a household cleaner and disinfectant, but its presence in a gas tank can cause serious damage to the engine. When bleach mixes with fuel, it can corrode the metal parts of the fuel system, leading to leaks and other issues. Additionally, bleach can react with gasoline and produce harmful gases that can be released into the environment when the engine is running. It is important to avoid adding bleach to gas tanks and to properly dispose of any fuel that has been contaminated with bleach.


Acetone is another chemical additive that can be found in gas tanks. It is commonly used as a solvent for removing paint and cleaning surfaces. While acetone is effective at breaking down substances, it can also have negative effects on the fuel system. When acetone is added to gasoline, it can cause the fuel to become more volatile, leading to increased evaporation and potential damage to the engine. Additionally, acetone can degrade rubber seals and gaskets in the fuel system, leading to leaks and other issues. It is important to avoid using acetone as a fuel additive and to only use it for its intended purposes.

Paint Thinner

Paint thinner is a solvent that is commonly used to thin oil-based paints and clean painting tools. However, it should never be added to a gas tank. Paint thinner contains chemicals that can react with gasoline and cause damage to the fuel system. When paint thinner mixes with fuel, it can lead to a decrease in the octane rating of the gasoline, which can result in engine knocking and decreased performance. Additionally, paint thinner can corrode metal parts of the fuel system and cause leaks. It is important to always use paint thinner for its intended purposes and to avoid using it as a fuel additive.

Household Products

Cooking Oil

Cooking oil is a common household product that can accidentally find its way into gas tanks. While it may seem harmless, the presence of cooking oil in a gas tank can cause significant damage to the vehicle’s engine.

  • Why does cooking oil cause problems?
    • Cooking oil is not designed to burn like gasoline, and when it enters the combustion chamber, it can create a thick layer of residue on the spark plugs and other engine components.
    • This residue can lead to misfires, reduced engine performance, and even engine damage if left untreated.
  • How does cooking oil get into gas tanks?
    • Accidental spills during refueling can allow cooking oil to come into contact with the gas tank opening.
    • Additionally, if cooking oil is stored near the gas tank or if the two substances are mistakenly switched, the oil can find its way into the tank.
  • Preventing cooking oil contamination
    • Always ensure proper storage and labeling of cooking oil to avoid mix-ups with gasoline.
    • Be cautious when refueling and make sure to wipe any spills immediately to prevent oil from entering the gas tank.

Dish Soap

Dish soap is another household product that can cause issues when it enters a gas tank. While it may not be as damaging as cooking oil, it can still lead to performance problems and require costly repairs.

  • What happens when dish soap gets into a gas tank?
    • Dish soap is designed to break down grease and grime, and when it enters the gas tank, it can disrupt the fuel system by creating excess foam.
    • This foam can lead to fuel line blockages, reduced fuel flow, and engine stalling.
  • How does dish soap end up in gas tanks?
    • Similar to cooking oil, accidental spills during refueling can allow dish soap to mix with gasoline.
    • If dish soap is stored near the gas tank or if it is mistakenly added to the tank instead of gasoline, contamination can occur.
  • Preventing dish soap contamination
    • Store dish soap away from the gas tank and always double-check before adding fuel to ensure no dish soap is accidentally added.
    • If a spill does occur, clean it up promptly and thoroughly to prevent soap from entering the gas tank.

Laundry Detergent

While it may seem unlikely, laundry detergent can also find its way into gas tanks. This can happen through accidental spills or if the detergent is mistakenly added instead of gasoline.

  • The effects of laundry detergent in a gas tank
    • Laundry detergent contains various chemicals, including surfactants and enzymes, that are not meant for combustion.
    • When laundry detergent enters the engine, it can create a thick residue on vital components, leading to reduced performance and potential engine damage.
  • How does laundry detergent end up in gas tanks?
    • Accidental spills during refueling can allow laundry detergent to mix with gasoline.
    • If laundry detergent is stored near the gas tank or if it is mistakenly poured into the tank, contamination can occur.
  • Preventing laundry detergent contamination
    • Store laundry detergent away from the gas tank and always ensure proper labeling and separation of products.
    • If a spill occurs, clean it up immediately and thoroughly to prevent detergent from entering the gas tank.

By being aware of the potential contamination caused by household products like cooking oil, dish soap, and laundry detergent, you can take the necessary precautions to prevent damage to your vehicle’s engine. Remember to always be cautious when refueling and ensure proper storage and labeling of household products to avoid mix-ups.

Non-Fuel Liquids

Motor Oil

Motor oil is a common non-fuel liquid that can contaminate gas tanks. It is used to lubricate and cool the engine, but if it enters the fuel system, it can cause serious damage. Here are some important points to know about motor oil contamination:

  • How does motor oil get into the gas tank? Motor oil can enter the gas tank through a variety of ways, such as a faulty seal or gasket, a cracked engine block, or improper maintenance.
  • What are the consequences of motor oil contamination? When motor oil mixes with gasoline, it can reduce the fuel’s octane rating and decrease engine performance. It can also clog fuel filters, injectors, and other components, leading to poor fuel flow and potential engine damage.
  • How can you detect motor oil contamination? Signs of motor oil contamination in the gas tank may include a strong smell of burning oil, black smoke from the exhaust, decreased fuel efficiency, and engine misfires. If you notice any of these symptoms, it’s important to have your vehicle inspected by a qualified mechanic.


Antifreeze, also known as coolant, is another non-fuel liquid that can find its way into gas tanks. While it is primarily used to regulate engine temperature, its presence in the fuel system can cause various issues. Here’s what you need to know about antifreeze contamination:

  • How does antifreeze contaminate the gas tank? Antifreeze can enter the gas tank if there is a leak in the cooling system, such as a damaged radiator or a faulty hose connection. It can also occur if the vehicle is mistakenly filled with antifreeze instead of gasoline.
  • What are the effects of antifreeze contamination? Antifreeze mixed with gasoline can result in poor engine performance, increased emissions, and potential damage to fuel system components. It can also lead to engine overheating, as the antifreeze may disrupt the combustion process.
  • How can you identify antifreeze contamination? Some signs of antifreeze contamination in the gas tank include a sweet smell from the exhaust, white smoke, engine overheating, and a decrease in fuel efficiency. If you suspect antifreeze contamination, it’s essential to seek professional assistance to prevent further damage.

Brake Fluid

Although less common than motor oil and antifreeze, brake fluid can still pose a threat if it enters the gas tank. Brake fluid is responsible for transmitting the force from the brake pedal to the brakes, but its presence in the fuel system can lead to serious consequences. Here’s what you should know about brake fluid contamination:

  • How does brake fluid end up in the gas tank? Brake fluid can enter the gas tank if there is a leak in the brake system, such as a damaged brake line or a faulty master cylinder. It can also occur if there is cross-contamination during vehicle maintenance.
  • What are the risks of brake fluid contamination? Brake fluid mixed with gasoline can cause damage to fuel system components, including fuel pumps, injectors, and filters. It can also affect engine combustion, leading to decreased power and potential engine misfires.
  • How can you detect brake fluid contamination? Signs of brake fluid contamination in the gas tank may include a pungent odor from the exhaust, decreased brake performance, engine hesitation, and increased fuel consumption. If you suspect brake fluid contamination, it’s crucial to have your vehicle inspected by a qualified technician to prevent further damage.

Remember, if you suspect any non-fuel liquid contamination in your gas tank, it’s always best to consult a professional for proper diagnosis and repair. Ignoring or attempting to fix the issue yourself can potentially cause more harm to your vehicle and compromise your safety.

Solid Objects

Have you ever wondered what kind of solid objects can end up in your gas tank? It may seem surprising, but there are a variety of items that can find their way into your fuel system. In this section, we will explore three common solid objects that can contaminate your gas tank: rags or clothing, plastic bags, and rubber gloves.

Rags or Clothing

It’s not uncommon for small pieces of cloth, such as rags or even clothing, to accidentally fall into the gas tank. This can happen during maintenance or repairs when a mechanic uses a rag to wipe off excess oil or fuel. These cloth pieces can easily get dislodged and end up in the tank, causing potential damage to the fuel pump or clogging the fuel filter. It’s important to be cautious and ensure that all rags and clothing are kept away from the gas tank during any work on your vehicle.

Plastic Bags

Plastic bags are another solid object that can find their way into the gas tank. They can enter the fuel system through various means, such as accidentally dropping a plastic bag near the gas tank or if it gets sucked in through the fuel filler neck. Once inside, plastic bags can obstruct the fuel flow, leading to engine performance issues or even complete engine failure. To prevent this, always be mindful of plastic bags and dispose of them properly, away from your vehicle.

Rubber Gloves

Believe it or not, rubber gloves can also end up in your gas tank. Mechanics and DIY enthusiasts often wear gloves when working on vehicles to protect their hands from dirt, chemicals, and fuel. However, if a glove is not removed properly or accidentally falls off, it can easily get sucked into the fuel system. The consequences of having a rubber glove in your gas tank can be severe, potentially causing damage to the fuel pump or injectors. To avoid this, it’s important to double-check that all gloves are accounted for and disposed of properly after any automotive work.

Miscellaneous Substances

Expired Medications

Are you wondering what can happen if you accidentally put expired medications in your gas tank? Well, let me tell you. Expired medications contain chemical compounds that can have adverse effects on your vehicle’s fuel system.

When medications expire, their chemical composition changes, and they may break down into harmful substances. These substances can clog fuel filters, injectors, and other components of your vehicle’s fuel system, leading to poor engine performance and .

Glue or Adhesives

Have you ever thought about what would happen if you poured glue or adhesives into your gas tank? It may seem like a strange idea, but some people have attempted it. However, let me warn you that it’s definitely not a good idea.

Glue and adhesives are designed to stick things together, not to be mixed with fuel. When exposed to gasoline, these substances can harden and form clumps, causing blockages in the fuel lines and filters. This can result in reduced fuel flow and engine damage.

Excessive Amounts of Alcohol

You may have heard that alcohol and gasoline don’t mix well, and that’s true. While a small amount of alcohol is often found in gasoline as an additive, excessive amounts can be problematic.

When you add excessive amounts of alcohol, such as rubbing alcohol or ethanol, to your gas tank, it can lead to several issues. Alcohol can damage rubber and plastic components in the fuel system, causing leaks and deterioration. Additionally, alcohol can also affect the combustion process, leading to engine misfires and decreased fuel efficiency.

To ensure the smooth operation of your vehicle, it’s best to avoid adding expired medications, glue or adhesives, and excessive amounts of alcohol to your gas tank. Stick to using the appropriate fuel recommended by your vehicle manufacturer and avoid any unnecessary experiments that could potentially harm your vehicle’s fuel system.

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