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What Happens If You Put Diesel In A Gas Car? Everything You Need To Know

in Ownership
Person filling up a car

Source: Pixabay

Unfortunately, while this is not an easy mistake to make, this happens more frequently than you might think. It happens to the best of us. You pull up to a gas station like you always did a hundred times before, but this time, you didn’t pay attention to the type of fuel you’re filling up on. Then, it was too late for you to realize that you had just pumped gallons of diesel fuel into your gas-powered car.

Whether you experienced this mishap or are just curious, you’re probably asking: what happens if you put diesel in a gas car? You should know that diesel contamination can have severe consequences on a gas-powered vehicle.

Today, we’ll discuss what happens if you put diesel in a gas car, what you should do when this happens, and some tips on how to prevent it. Let’s get to it!

What Happens If You Put Diesel in a Gas Car?

You should know that there are several safeguards to ensure that patrons don’t put the wrong type of fuel into their cars. For instance, the nozzles of diesel fuel pumps are larger in diameter than your standard gas pumps. Thus, if you try to insert the diesel nozzle into a gas-powered car, it will likely not fit – however, some people did manage for some reason.

In addition, diesel fuel pump handles are usually marked with a bright green or yellow color, so customers can identify which pump is which. As you may have realized, some people have managed to bypass these safeguard solutions.

So what actually happens when you put diesel in a gas-powered car?

If there are still a couple of gallons of gas left on the tank, your car will likely run but rather poorly. However, once all the remaining gas is used up, the engine will stop running because, essentially, you have no more fuel. This is because gasoline engines simply aren’t designed to combust diesel fuel. The diesel fuel type is low in octane and denser than gas, the pump can’t transport the diesel throughout the engine.

In addition, diesel won’t easily move through the fuel filter and cause a blockage instead. Plus, any diesel amount that makes it into the engine will also congest the injectors. This will cause the engine to gum up or seize and result in significant damage.


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What Happens If You Put Gas in a Diesel Vehicle?

Now that you know what happens if you put diesel in a gas car let’s reverse the situation. What happens when you accidentally put gasoline on a diesel vehicle? Conversely, gas nozzles are smaller than diesel ones, so they’ll easily fit in a diesel-powered car.

If you’ve only pumped minimal amounts of gasoline in your vehicle before realizing your mistake, you may be able to get away with diluting the gas by pumping more diesel. It’s not ideal and bad for fuel economy, but it’s unlikely to cause any significant problems.

On the flip side, pumping significant amounts of gasoline (let’s say a full tank) in your diesel-powered vehicle can be a costly mishap. Diesel engines employ a different combustion process than gas engines, and the former uses high-pressure combustion. At this point, simply turning the ignition to the “ON” position will potentially cause engine damage as the fuel circulates the system.

The copious amounts of gasoline will ignite too early in the combustion process, causing the motor to misfire and damage several internal engine components, including the pumps and injectors.

What Should You Do After Putting Diesel in a Gas-Powered Car?

If you’re lucky enough to catch your mistake of putting diesel in your gas car, the best thing to do is not panic, but you have to act quickly. If you only fill your tank with minimal amounts of diesel fuel (less than 50% of your tank), you may be able to drive your car to the nearest garage or auto shop and have the diesel drained.

However, the safest approach is to avoid operating the vehicle at all. This minimizes the possibility of sucking up the diesel into your car’s fuel line, which may lead to mechanical damage and extensive repairs. At this point, you should contact a roadside assistance service to tow your vehicle to the nearest mechanic or auto shop.

If your car has a removable tank drain, then it should be a simple job of opening the drain and emptying the contaminated fuel from the tank. Afterward, the tank will be pumped with gasoline and repeat the draining step to ensure that all remnants of the diesel is flushed out. The mechanic may repeat this step to ensure the tank is clear from diesel contamination.

On the other hand, if your vehicle doesn’t have a removable drain, the mechanic will need to remove the tank from the car to drain the diesel. Similarly, the tank will need to be repeatedly rinsed using gasoline until no trace of diesel is left.

For draining fuel from the tank, expect to pay around $200-$500, which will depend if the gas tank has to be taken out of the vehicle or not. If the diesel finds its way into the fuel line, you’ll need extensive repairs, and the cost may rise to between $1,500-$2,000.


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Always Pay Attention

Hopefully, we’ve answered your question, “what happens if you put diesel in a gas car?” The takeaway is that you should always pay attention when pumping fuel. As discussed earlier, diesel pumps are usually green and have larger nozzles. The nozzle that won’t fit into your gas-powered vehicle should signal that you’re filling the wrong fuel type. If you’re storing fuel at home, make sure each container is color-coded and properly labeled to avoid putting in the wrong fuel.

Lastly, the important thing is not to panic in case you make this mistake. Once you realize your error, don’t drive your vehicle and call a roadside assistance service immediately.


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