What Happens if You Put Diesel in a Gas Car?

By Chris Hardesty 08/28/2023 7:00am

Diesel fuel pump handle

Diesel and gasoline are different types of fuel, and an engine that operates with one type isn’t compatible with the other fuel. So, what happens when you put diesel in a gas engine? Just putting diesel fuel into a gasoline car is bad enough. Attempting to drive a vehicle with diesel in a gas engine will cause it to stall as soon as diesel reaches the intake system, potentially clogging the fuel lines and damaging the engine.

What Happens When You Put Diesel in a Gas Engine?

Diesel is thicker than gasoline, and the more viscous fuel can clog and damage a gas engine’s injection system and other components. If you catch yourself putting diesel in a gas car, here’s what to do (and not do):

  • Do not start the engine. It’s crucial to keep the diesel in the tank and not let it into the fuel lines and cause damage.
  • Do not panic. Mixing the two fuels is not, by itself, dangerous.
  • Immediately call a dealership or local repair shop. Arrange for an emergency tow to get your vehicle to the service center.

A mechanic will drain and rinse the gas tank to remove diesel and its residue. If you didn’t start the engine, that’s the only service necessary. However, additional work may be needed if you drove with diesel in the gas tank. If you ran the engine until it stalled, technicians will likely:

  • Flush the fuel line
  • Service the fuel injector system
  • Check the fuel pump for damage
  • Replace the fuel filter

Tips to Avoid Diesel Into Gas Engine

Incidents of putting diesel into car gas tanks are infrequent but not unheard of. To avoid mistakenly getting diesel fuel in your gas car, pay attention at the pump and don’t pick up handles with a “Diesel” label.

  • Diesel pumps typically have green handles that give you another visual clue of the fuel type.
  • The nozzle on a diesel pump has a larger diameter than its gasoline counterparts to prevent inserting it into the gas tank’s opening.
  • Diesel smells like kerosene, while gasoline smells more like paint thinner.

Human error is the reason for diesel in gas tanks. However, the mistake isn’t always the car owner’s fault. Fuel contamination can happen at the distributor level and potentially cause problems for thousands of drivers.

Consumers in Southwest Florida faced such an issue this week. A supplier provided gasoline with a strong likelihood of being contaminated with diesel fuel to at least 30 service stations in greater Tampa.

That widespread contamination accident occurred as Tropical Storm Idalia approached Florida’s west coast, as its residents were taking steps for hurricane preparation.