What Will Happen If You Put the Wrong Fuel in Your Car

car fuel

You’ve got a lot of things on your mind, and in your attempt to multitask, you suddenly just find out that halfway through filling your car up with gas, you’ve picked the wrong fuel. What’s going to happen? Will your car just spontaneously combust and blow up? Well, fortunately, that won’t happen. However, it can damage your vehicle, and sometimes for good.

Today, we want to talk about the impact of misfuelling your car, specifically the type of fuels and the damage they can cause to different types of vehicles:

1. Diesel in a Petrol Vehicle

It is improbable that you will be able to insert a diesel fuel pump into a vehicle that runs on petrol, as they are not compatible. Yet, in rare cases, this mistake can be made.

Fortunately, using diesel fuel in a petrol car won’t cause permanent damage. However, when diesel fuel is used in a petrol car, it can cause a few problems. The fuel will clog up the car’s system, preventing the petrol from getting to the engine. This can lead to a lack of power or a complete breakdown. In some cases, the car may even start to smoke. In addition, using diesel fuel in a petrol car can cause damage to the fuel injectors and spark plugs. This can cause a decrease in fuel efficiency and an increase in emissions. The car may also suffer from starting problems.

So, how do you fix this problem? It’s quite simple. You just have to drain the tank and flush the fuel from the system. However, you may need to replace any damaged parts like spark plugs.

2. Petrol in a Diesel Vehicle

Unfortunately, unlike diesel in a petrol vehicle, the consequences here are much dire. Plus, because the nozzle of the petrol fuel pump is smaller, the chances of this happening are much higher. Just remember that if you have mistakenly put petrol into a diesel car, it is important that you do not turn on the car’s engine. Otherwise, it can cause a lot of damage.

Why is this the case? Diesel works as a lubricant in the fuel pump, allowing it to work as designed. Petrol, on the other hand, will increase the friction in your diesel engine, leading to a lot of wear and tear on the fuel pump and other parts. If the issue is not addressed in time, it could result in the need to completely replace the engine.

On the off chance that you’ve put only a minuscule amount of petrol in the vehicle, you should be able to start the car and drive it smoothly. However, to avoid any risk, we always recommend having the engine drained. While there’s a small fee to this, it is much cheaper than having to outright replace the engine.

3. E10 in Incompatible Vehicles

Back in 2021, the United Kingdom transitioned to E10 petrol which contains 10% renewable ethanol, compared to E5 petrol, which had 5%. This change was implemented to help reduce the amount of CO2 emissions. Unfortunately, it is reported that over half a million cars on British roads are not compatible with the new fuel.

The good news here is that if you own an E5 vehicle but put E10 into it, it shouldn’t cause much damage if any. However, repeated mistakes can lead to damage to the internal structure of your engine. So, if you do find yourself putting E10 in an E5-only vehicle, be sure to pump in some E5 as quickly as possible to dilute the E10 and make your car safe to drive.


Mistakes happen, and we don’t blame you. Add to the fact that many of these nozzles aren’t exactly standardised, you can easily find yourself grabbing the wrong one. So, always be mindful when fueling your car. Pay attention to the signage, and consider putting a small reminder on the inside of the fuel cap to remind you of what type of fuel to put in the car! That way, you save yourself a whole world of travel and can easily drive out of the gas station and move on with your day.

Fuel Fixer offers mobile units across the UK to help individuals who have inadvertently put the wrong fuel in their car get the service they need to get the issue fixed. If you are looking for wrong-fuel cleanup services, get in touch with us today!

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