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What Happens if You Put Diesel in a Gas Car

What Happens if You Put Diesel in a Gas Car

You can see there are different types of cars available in the market where some of them are gasoline cars and some are diesel cars. It is necessary to take care of this thing and avoid making a mistake putting diesel in a gasoline car. You must be thinking what happens if you put diesel in a gas car? You must know that it might damage your car’s engine and can affect the performance of your car badly.

No doubt, it is a common mistake that the drivers do not pay attention sometimes and put diesel in the gas car. The level of damaging the car depends upon the amount of fuel added to the car. Moreover, it is not an easy mistake to make because the diesel pumps and gas pumps are labeled differently which helps in making a difference among them.

What Happens if You Put Diesel in a Gas Car?

Following are some of the effects of putting diesel in a gas car:

1. Performance is Affected

The performance of your car will be affected badly if you put diesel in your gas car. You will find difficulty in driving the car as it will not run smoothly. Moreover, it may also stop on your way to your destination. The pump might also get damaged due to this mistake.

It would be best if you check the pump before driving because the pump will find it difficult to move the mixture of gasoline and diesel through the system. Moreover, the diesel can also not pass through the fuel filter easily as it will clog up the filter.

2. Gasoline Combustion

If you inject fuel into your gas car, its side effects are shown before the intake valve opens for allowing the air to enter the cylinder. The fuel and air are mixed when the piston moves upwards. It results in heating the mixture of fuel and air which makes it easier for the mixture to ignite.

In this condition, a spark is delivered by the ignition system via the spark plug that acts as a heat source for igniting the mixture of fuel and air. This process is started at the tip of the spark plug. You should know that the gasoline engine of a car is used to combust the fuel in the mixture of air and fuel.

3. Hard To Start The Car

If you add a large amount of diesel to the gasoline car, it will be difficult for you to start the car due to the increase in the viscosity of the fuel. It is because the fuel is thicker than the gas and does not vaporize efficiently and sufficiently for forming a homogenous mixture along with the intake air.

Moreover, the diesel remains concentrated in a single jet when you put it in a car. It can also get broken up into droplets that are considered too large for sustaining even combustion. Thus, it makes it difficult to start the car when you accidentally put diesel in your gasoline car’s engine.

4. Car Will Smoke Heavily

You will notice your car is smoking heavily after you put diesel in your gasoline car. You should know that the diesel needs high compression pressures to ignite. That’s why you will notice the clouds of black or white smoke getting exhausted from the tailpipe of your car.

As we know the engines are not capable to generate sufficient compression pressure for igniting the diesel, some amount of it does not combust due to gasoline combusting. In such a situation, neither the diesel nor the gas in the fuel will combust completely. Thus, there are thick clouds of smoke coming from your car. This smoke can be dangerous for other people on the road behind you.

5. Failure of Catalytic Converters

The catalytic converters present in your car can get damaged if you put diesel in the gasoline car. You should know that the gas cars are enriched with a limited amount of unburned hydrocarbons that’s why contaminated gas can result in increasing the unburned hydrocarbons in the exhaust stream and the catalytic converter becomes clogged.

The failure of the catalytic converter depends upon the concentration of diesel. The exhaust backpressure can result in increasing above the maximum threshold for the car when the catalytic converter gets clogged. It not only results in reducing the performance of the engine but can also overheat it.

The best solution to this problem is to remove all the traces of diesel from the fuel system of your car and install a new catalytic converter. No doubt, it would be expensive to replace a catalytic converter with a new one.

6. Engine Power Loss

If you put diesel fuel in your gasoline car, the power of its engine will be lost. We know that the functioning of the engine depends upon how well the fuel is combusted in the engine. Putting diesel in the gasoline engine results in losing the power of the engine and poor combustion.

If the engine is still running properly, you can experience any serious issues later. For example, it can cause serious misfires. It can also result in increased fuel consumption and poor idling quality.

When you accidentally add some fuel to your gas engine, the diesel does not get mixed with the gasoline because diesel is a lubricant but not gasoline. The mixing up of diesel and gasoline can jam the fuel pumps. But you should know that no amount of diesel can damage the gasoline engine. It can also stop the engine for some time.

What to do After Putting Diesel in a Gas Car?

You should not get panic if you accidentally put diesel in the gas engine. For your information putting gas in a diesel car is more dangerous than putting diesel in a gasoline engine. When you realize you have made a mistake putting the diesel in your gasoline car, it requires immediate action to fix this issue.

You should not leave the diesel in the tank for a long period of time because it might damage the engine. Moreover, you should also not start your car in this condition even if you are in a hurry. You should park your car in a car, tow it for drainage purposes. If you start your car and run it, it can cause the diesel to enter the fuel line as well as the engine system which can make the repair process costly and complicated.

1. Remove Drain

If your car has a removable drain on the gas station, it would be best to remove it for drainage purposes. This drain can easily be opened by the mechanic and the amount of diesel and gasoline mixture can be emptied from it. You may have to perform this task repeatedly for clearing the tank from all the diesel contamination.

2. Dropping The Tank

It is obligatory to use the “dropping the tank” technique if your car does not have a removable drain. You will have to remove the tank from your car for draining purposes. Then, the tank is needed to rinse repeatedly using fresh gasoline until all the diesel fuel is gone away or washed out.

You may have to spend more than 200 dollars to drain the tank of your car. But this cost greatly depends upon the drain present on the gas tank whether it is removable or not. If the diesel enters the engine or fuel line of your gasoline car, it will cost you more than 1500 dollars to fix this issue.

3. Take Out The Diesel

You can remove the diesel from the gas engine with the help of the siphon method or any other method that could help you take out all the diesel from the engine. Take an empty bucket with you and fill it with the diesel you extract from the engine.

It requires you to fill the tank with the gas when all the diesel is out of it. Start your car after putting gas in it. it may take some time to start your car. You may also notice the heavy clouds of smoke coming from your car until all the diesel fades away from the fuel system.

Importance of Hiring A Professional

It would be best if you hire a professional mechanic if you have put diesel in your gas engine. It is because the professionals are aware of such situations and they know about the right techniques and tools to use for fixing this issue. Plus, you can get professional assistance in no time to get this problem fixed immediately.

The professional mechanics know how to drain the gas engine and how it should be towed. They can flush out all the diesel from your car’s engine. It is necessary to hire a mechanic immediately because the fuel pump can get damaged if the diesel stays in your gas car for a long time.

The diesel can also result in affecting the air filters and spark plugs present in your car. If you do not fix this issue immediately, you may need to replace the spark plugs and air filters with new ones. And we know that replacing car parts is more expensive than fixing the issue as soon as possible. Hiring a professional mechanic will not cost you more than 100 dollars.

Difference Between Diesel Fuel and Gasoline Fuel

The major difference between diesel fuel and gasoline fuel is that diesel is used by heavy-duty vehicles, boats, semis, trucks, and busses. These vehicles need more low-end pulling power and a higher torque rating. On the other hand, gasoline powertrains are related to light-duty trucks, SUVs, and passenger cars.

We know that both gas and diesel are derived from crude oil but they both have different physical properties. The gasoline consists of a distinct smell and is thinner than diesel. On the other hand, diesel is thicker than gasoline fuel and is also lightweight.

The physical difference in both fuels causes problems if you put diesel fuel in gas cars and gasoline in the diesel engine. It is because the engines are designed according to the fuel to be used. Moreover, diesel fuel is not combustible as compared to gasoline fuel.

How To Avoid Putting Diesel in Your Gas Car?

You can differentiate the handle of diesel fuel and gasoline fuel from their color. Typically, the color of a diesel pump is green so you should keep in mind that the green one is for diesel fuel and you should not use it if you have a gasoline car.

1. Color

The color of the gasoline pump handle is typically black. We know that both the pump handles are placed together but you must know the difference between them depending upon their color. The gasoline pump handle may also consist of octane rating cards at its top.

2. Nozzle

There is also a difference between the nozzle of both the pump handles. You must check the nozzle size before filling your car with fuel. You should know that the size of the diesel fuel pump’s nozzle is larger as compared to that of the gasoline tank.

3. Fuel Tank

Due to the difference in opening of both the tanks and nozzles, you cannot insert the nozzle of a gasoline pump into a diesel car and a diesel’s nozzle into a gasoline car. Though it is difficult to insert it that’s why we cannot say that it is an easy mistake to make.

4. Odor

You can also differentiate diesel fuel and gasoline fuel on the basis of their smell. No doubt, they both have a different smell. You can easily differentiate the difference between both of them. So, if you accidentally pull out the diesel pump handle to put it into your gas car, its smell can easily tell you that you are handling a diesel pump handle, not the gasoline pump handle.

Incompatibility of Both Engine Types

Both engine types are incompatible with each other so you cannot run a gasoline engine on diesel and a diesel engine on gasoline. The thick fuel is not suitable for the gasoline engine that’s why if you add it to the gasoline engine, it might get damaged and its performance gets affected. Similarly, the diesel engine cannot handle the addition of gasoline in it.

1. Thermal Efficiency

The thermal efficiency of both the engines is also different. You should know that the thermal efficiency of a diesel engine is 20% more than that of a gas engine. Medium duty vehicles use diesel engines due to their increased fuel efficiency. Plus, their operating cost is also low. They are considered best for medium-duty vehicles due to their reliability.

2.  Volatility

The volatility of gas engines is more as compared to diesel engines. Spark plays a vital role in controlling the combustion of the gas engine. On the other hand, the diesel engine does not involve the usage of a spark that’s why it is known as the compression combustion engine.

3. Expectancy

The life expectancy of both the engines is also different. For example, you can cover 120,000 to 150,000 miles if your car has a gas engine. If you try to cover more distance, the efficiency of the engine will be decreased. On the other hand, diesel engines are well-known for their long life. You can cover millions of distances with them without facing any problem in your way.

Frequently Asked Questions

1. What happens if you put diesel in a gas car?

The engine of your car can get affected badly if you put diesel in your gasoline engine. You can find it difficult to run the car properly. Thus, its performance is affected badly.

2. How can you fix this issue when you accidentally pour diesel into the gas engine?

The best method that can be used for this purpose is to drain the fuel tank present in your car. In this way, you can remove the mixture of gas and diesel from your car completely.

3. Can your gas engine get damaged due to putting diesel in it?

It depends upon the amount of diesel you put in your gas engine. If you put a small amount of diesel in it, the engine will not be harmed but it will result in lowering the octane rating a little bit which can affect the acceleration of the engine.

4. How much does it cost to drain your gasoline engine?

It costs about 400 to 800 dollars to get your gasoline engine drained after you accidentally put some diesel fuel in it.

5. What is the major difference between gasoline fuel and diesel fuel?

The major difference between both these fuels is the difference in density. Gasoline fuel is thicker than diesel fuel.

6. How much does it cost to hire a mechanic to drain your car’s engine?

It costs about 100 dollars to hire a professional mechanic for this purpose.


It is not a common mistake when you put diesel in your gas car. It is because there is a clear difference between the pump handles of diesel and gas. You must know the color difference and the difference in their smell. You must tow your car immediately and get professional assistance when you accidentally put diesel in the gas engine.

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