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What Happens When You Put Diesel in a Petrol Car?

Misfuelling, such as putting diesel in a petrol engine, can lead to serious complications. This blog explains the consequences, focusing on the problems that arise when diesel is used in a petrol car. Learn about lubrication issues, combustion problems, fuel system contamination, and more. Stay informed to avoid misfuelling, ensuring the longevity and optimal performance of your vehicle. Additionally, having car insurance is crucial for financial protection in case of any unexpected issues, providing peace of mind for car owners.

  • 21 Nov 2023
  • 3 min read


Filling your vehicle's tank with the incorrect fuel type is an easy but potentially costly mistake. While misfuelling a diesel-powered vehicle with petrol is common due to the larger nozzle on diesel dispensers, it's essential to learn what will happen if diesel is used in petrol engine. This blog explores the consequences and solutions for such misfuelling incidents, emphasising the importance of using the right fuel.


Why should you avoid putting diesel in a petrol car?

Now, let us focus on what happens if diesel is used in petrol engine. Misfuelling, or putting the wrong type of fuel into a vehicle, can lead to serious complications, and one common mistake is putting diesel into a petrol engine.


Here is why this is problematic: the primary difference between petrol and diesel engines is their combustion process. Diesel engines use compression ignition, while petrol engines use spark ignition. Because diesel is denser and oilier, it's designed to self-ignite under high pressure.


When diesel is mistakenly added to a petrol car, the engine doesn't operate efficiently because petrol engines aren't designed to handle diesel's thickness and lubricating properties. In contrast, petrol lacks these lubricating properties, and when introduced into a diesel engine system, it can cause insufficient lubrication, leading to metal components grinding against each other. This can lead to significant wear and tear, possibly damaging the engine's internal components.


Moreover, diesel has a higher flash point than petrol. This means it requires more heat to ignite. This can lead to poor combustion, reduced engine performance, and potential engine misfires. To ensure the longevity and optimal performance of your vehicle, it's crucial to use the fuel specifically designed for its engine type.


What are the problems of misfuelling?     

Misfuelling, or putting the wrong fuel in your vehicle, can lead to various problems, depending on whether you've put petrol in a diesel or a petrol car. Now check these points telling what happens if we put diesel in petrol car:


Misfuelling with Petrol in a Diesel Car:

  • Lubrication Issues: Diesel engines rely on the lubricating properties of diesel fuel to operate efficiently. When petrol is used, it lacks the necessary lubrication, leading to potential damage.
  • Combustion Problems: Petrol doesn't ignite in the same way as diesel. It can cause combustion issues, leading to poor engine performance, knocking, and potential damage to the engine.
  • Fuel System Contamination: Petrol can contaminate the diesel fuel system, including the fuel lines, injectors, and the fuel tank. This contamination can lead to clogs and reduced engine efficiency.
  • Starting Problems: Attempting to start a diesel engine with petrol in the tank can result in difficulty starting or even engine stalling.
  • Emission Concerns: Misfuelling can increase emissions, contributing to environmental pollution and potentially violating emissions regulations.


Misfuelling with Diesel in a Petrol Car:

  • Clogging of Fuel System: Diesel has a thicker consistency than petrol and can clog the fuel system in a petrol car. It includes the fuel lines, injectors, and the fuel filter.
  • Spark Plug Issues: Diesel's properties can lead to issues with the spark plugs, affecting the ignition process and potentially causing misfires.
  • Fuel Filter Damage: The fuel filter in petrol engines is not designed to handle diesel, and its use can lead to fuel filter damage.
  • Engine Misfires: Misfuelling can result in engine misfires, producing exhaust smoke and potentially causing the car to stall.
  • Reduced Fuel Efficiency: The incorrect fuel can lead to reduced fuel efficiency, increasing fuel consumption and operating costs.
  • Engine Damage: If the engine is started with diesel in the petrol car, it can lead to significant engine damage and potentially costly repairs.

Also read:


Now you know what happens if you put diesel in a petrol car. It is a more common mistake than one might think. You must stay focused and alert when refuelling your vehicle to avoid such errors. Avoid refuelling when tired, place reminders near the fuel cap, and always use the correct fuel type. Additionally, having car insurance is a legal requirement in many countries, providing financial protection in case of accidents, theft, or damage. Car owners must be adequately insured to avoid legal penalties and financial risks.

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