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What Happens if You Put Gas in a Diesel Car? What You Need To Know!

person pumping gas on the car

Vehicle manufacturers and gas station designers have done their best to prevent it from happening. Still, no one is immune from the possibility of putting the wrong fuel in their vehicle. If a diesel engine is filled with gas, the damage is not done until the car fires up and drives away. And even then, if the added gas is less than around 10% of the total gas-to-diesel ratio, there may not be permanent damage.

How quickly you realize that the wrong fuel was put in the car will determine the repair cost. It may be as inexpensive as a few hundred dollars. But if extensive damage is done, it can get to upwards of $5,000 and beyond.

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What’s the Worst That Could Happen?

If the diesel engine is filled completely with gas or there is no way to tell what the ratio of the mixture is, then it is essential not to fire up the vehicle. The vehicle will need a tow to a trusted dealership or mechanic to have the fuel tank removed and cleaned. This is the best-case scenario.

A worst-case scenario is that you drive away from the gas station before realizing the diesel engine just got filled with gas. If this happens, pull over immediately. An automotive mechanic will have to remove and clean the fuel tank, but in this case, they will also have to flush your fuel system completely. If you didn’t drive very long with gas or if the ratio wasn’t too much, then the damage may be minimal, but there will likely be some damage in your engine.

The worst-case scenario is not realizing your diesel car was filled with gas until the engine stops as you’re driving. Once it’s gone this far, there could be catastrophic damage in the engine that will need to be diagnosed and fixed by a professional. And unfortunately, there aren’t any manufacturer warranties that will cover damage from gas in a diesel engine—or vice versa.

pouring fuel on gas tank
Image By: Pixabay

Difference Between Gas and Diesel

You might wonder what the big deal is. What makes these two types of fuel so different? Besides being different on a molecular level, a few key differences drastically change how the engines that run them respectively were designed.

  • Ignition: Gas engines rely on sparks plugs to ignite the gas, whereas diesel ignites from the compressed air in the engine. So, if gas is put in a diesel engine, it will not ignite properly and ruin the injectors.
  • Lubrication: In addition to powering the engine, diesel fuel is actually designed to lubricate the engine components as well. Gas is a solvent, so it does the opposite. This is a significant contributor to the catastrophic damage that gas can cause in a diesel car. Because gas will not lubricate the engine and the components will destroy each other.
  • Sensor Issues: The thing with modern vehicles is they are heavily reliant on computer systems to function correctly. If all the above-mentioned things are happening in the engine due to incorrect fuel, the computer will malfunction. The worst-case scenario is that the increased engine temperature could actually ruin the electronic monitoring systems, which comes with a hefty bill to replace.
fuel pump close up
Image By: ResoneTIC, Pixabay

What About Diesel in a Gas Engine?

The same kind of damage doesn’t immediately happen if the reverse occurs. There’s no doubt that diesel in a gas engine will still cause irreversible damage. It just doesn’t happen as quickly. That being said, the same advice applies to this situation. If the wrong fuel is put in the tank, the best option is to have the vehicle towed to a mechanic without it being fired up to minimize the repairs that need to be done.

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Obviously, it should be avoided, but there’s no need to panic if this should ever happen to you, especially if you realize the mistake before firing up your car. Other than an unexpected bill of a few hundred dollars, there will be no permanent or over-the-top expensive repairs. While this seems like a really silly mistake that no one should make, tons of people have made it and will continue to make it, so there’s no reason to be embarrassed!

Featured Image Credit: paulbr75, Pixabay


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