Diesel fuel in petrol car, petrol fuel in diesel car: Here’s what may happen

This happens more often than you think it does. A lot of people mistakenly fill petrol in a diesel car an diesel in a petrol car. So, what exactly when fill petrol in a diesel car, or vice versa. Let’s find out.

As the video details,

When you fill diesel in a petrol engined car, the engine may not start at all. But this is true only of those cars that are completely dry, with no petrol even in the fuel lines. In cars that already have some fuel left, which applies to almost all cars, the engine is likely to start normally. And that’s what happens in this video.

Diesel fuel in petrol car, petrol fuel in diesel car: Here’s what may happen

The petrol car judders when it’s being run on diesel, as diesel clogs up the fuel filter. Spark plugs fouling due to diesel could also be the cause of juddering. And when the diesel is replaced with petrol, it continues to drive normally. An emission check reveals that the catalytic converter (very sensitive to fuel changes) is working normally.

The car’s emissions also continue to meet regulations. So, you may get away a bit easily if you fill diesel in a petrol car, but it’s best that you drain the car’s tank and fuel lines completely once you realize this mistake.

When you fill petrol in a diesel car, the car may start and drive normally, but unknown to you, a lot of parts may get damaged. Diesel lubricates the fuel pump, so driving a diesel car on petrol is likely to damage the fuel pump, or reduce its working life drastically. Failing an emission test is also highly likely.

Diesel fuel in petrol car, petrol fuel in diesel car: Here’s what may happen

The car is likely to start stalling and turn sluggish, just as the video shows. Even after petrol is replaced with diesel, the car may continue to stall again and again, due to the damaged fuel pump. Modern day diesels could see many more components of the fueling system such as the injectors and common rail showing damage.

 However, you must avoid misfueling the car. Here’s why. 

  1. Modern day cars, both petrol and diesel, are sensitive to fuel changes. You risk major engine damage if you drive around with a different fuel.
  2. Insurance, in most cases does not cover misfueling. Engine damage could leave you with a massive hole in the pocket as modern engines are very expensive to rebuild.

Continued: What to do if you put diesel in a petrol car or petrol in a diesel car?

Jayprashanth Mohanram

Jayprashanth, the News Editor at, has a seasoned history in motoring journalism spanning 15 years. His lifelong passion for cars led him to a career in automotive journalism, offering readers compelling insights. With an engineering background, Jay has crafted pieces that have gained recognition in notable publications such as the New York Times. Prior to his role at, where he has overseen news operations since 2016, Jay was the founding editor of and spent two years as the news editor at Team-bhp. At Cartoq, he ensures the news is timely, accurate, and resonates with the brand's dedicated audience of automotive enthusiasts. (Full bio)