What Happens if You Put Diesel in a Gas Car?

Diesel and gasoline are the most common fuel types used in internal combustion engines., Diesel and gas work very differently, and are not interchangeable. Running a gasoline engine with diesel in it can cause extensive problems. Although uncommon, people have accidentally put diesel in their gasoline vehicles. In this article, we are going to look into what can happen to your gas-powered vehicle if you mistakenly fill the tank with diesel.

Green diesel pump handle in car

How are diesel and gasoline different?

Both gasoline and diesel are petroleum products, but diesel is less refined and more dense. This means that gasoline burns quicker and is more volatile, while diesel burns slower but more efficiently, producing 20% more power than traditional gas while burning the same volume of fuel. 

One of the main differences is diesel’s flash point, which is much higher than gasoline. The flash point is the minimum temperature a liquid needs to ignite. Diesel’s high flash point means that it is not able to be ignited traditionally.

Instead, diesel engines use glow plugs to increase the pressure and temperature to the optimal point to combust the diesel initially. Diesel engines rely on this high pressure in the cylinders to ignite their fuel, while gasoline engines simply use spark plugs. 

What happens if I run diesel in a gasoline engine?

Introducing diesel fuel into a gasoline engine will cause major issues. If you accidentally put the wrong fuel in your car, you can avoid the majority of problems by not starting the engine. 

With diesel being a denser liquid, it can clog the intricate fuel systems designed for thinner fuel. From the fuel filter to the injectors, various components may become gummed up with the thicker fuel. This can cause the engine to seize and require extensive work to return to working condition.

While still very harmful, diesel in a gasoline engine is not nearly as damaging as the opposite. Due to gasoline’s low flash point and increased volatility, running gas in a diesel engine can cause the motor to quite literally blow itself up.

What should I do if I put diesel in my gas-powered vehicle?

If you’ve put diesel in your car that runs on gas, don’t panic. The first and most important thing is to not turn on the vehicle. Running the engine will force the diesel fuel into the fuel lines, injectors, and fuel filter, leaving the fuel system inoperable.

Have your vehicle towed as soon as you can, as you should avoid letting the diesel sit in your vehicle even if you are not running it. Take it to a trusted professional and they will inspect your fuel system and motor for any damage, as well as drain your fuel tank to remove the diesel.

How can I avoid putting diesel in my gas tank?

It’s pretty difficult to put diesel into a gasoline vehicle at the pump. Diesel fuel pumps have a larger diameter nozzle that won’t fit into the port on most gas cars and trucks. A more likely scenario would be accidentally filling your car with diesel from an improperly labeled gas can. That being said, diesel nozzles and stickers are usually green or yellow and will always be labeled as diesel, while gasoline will have a black or red pump with various octane numbers labeled in yellow or red.

Diesel and gasoline buttons on a fuel pump

Fuel system service in Northern Idaho

If you’ve accidentally filled your vehicle with diesel, or need fuel system service of any other kind, the ASE-certified technicians at Lake City Auto Care have you covered! Call or schedule online and trust the experts at any of our three locations to get your car running as it should.

North Idaho's Best Warranty

We stand behind our work 100%. That's why we offer a five-year, 50,000-mile warranty on all services and repairs. You can rest assured that when you bring your vehicle to us, we've got you covered no matter what happens down the road.

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