Picture this : it’s early, you’re tired (perhaps you’re also late for something) and the car needs fuel. You’re halfway through filling up with ‘unleaded petrol,’ when you have a quick glance at the pump and the realisation suddenly dawns on you.
“Does that say… diesel?”
Oh no! You’ve put the wrong fuel in your car.
Mistakes happen to the best of us; according to the RAC, approximately 150,000 people in the UK put the wrong fuel in their vehicle every year - so you’re not alone.
Misfuelling can be an expensive error, but if you’re clued up on how to tackle it, you can significantly reduce the damage to your engine (and your wallet).
Our experts at Eurorepar weigh in on what to do if you put petrol in a diesel car and vice versa, what happens inside the engine, and tips for how to prevent a fuel mistake from happening again.
What happens if you put petrol in a diesel car by mistake?
This is the most common kind of misfuelling as the petrol nozzle can fit into the diesel filler neck, making it an easy mistake to make. It is also the more damaging type of misfuelling and can require a brand new engine if you’re unlucky.
Diesel acts as a lubricant helping the fuel pump to send fuel where it needs it. Petrol is a ‘thinner’ fuel, so when it’s pumped into a diesel engine, it will do the opposite by increasing the friction between parts and cause any repair costs to shoot skywards.
What happens if you put diesel in a petrol car?
The diesel pump nozzle is bigger than the petrol one, so this is a less common fuel mistake. However, if you do manage to put diesel in a petrol car, it will go into the tank, clog the fuel system and stop the car from starting. Although it is a big inconvenience, this can be easily resolved and shouldn’t result in any lasting damage.
What to do if you put petrol in a diesel car (or vice versa)
If you do make the mistake of putting the wrong fuel in your car, these tips will help to reduce the damage done to your engine. Take note!
Do not start your car
The no. 1 rule after misfuelling is: do not start your car and do not drive anywhere. Once the ignition key is turned, the wrong fuel is going to be pumped straight through the engine and cause extensive damage. By keeping your car turned off, you’re mitigating the damage and making the removal of the wrong fuel easier.
Get to a safe location
Put your car or van in neutral and get to a safe location if you can, whether you’re at a petrol station or on the side of the road.
Call for breakdown
Most breakdown policies will offer you misfuelling cover. If you’re covered, just give your provider a call once you’re safe to do so. If in doubt, try the AA or RAC – you don’t have to be a member to get immediate assistance and get your engine flushed.
Wrong fuel in your car symptoms:
So, what are the ‘symptoms’ of putting the wrong fuel in your car?
The engine won’t start – in some vehicles, the engine will not start at all however, this isn’t always the case. If this does happen, seek assistance from the attendant at the fuel station to check whether you have put the correct fuel in.
Engine cut out – you might be able to start your engine, only to have it cut out after a few minutes and not restart.
The engine warning light appears – you may also see the engine warning light appear on the dashboard.
Smoke from the exhaust – if you manage to start your engine but see an excessive amount of smoke coming from the exhaust, this is likely a symptom of misfuelling.
How to prevent a fuel mistake?
Be vigilant – get in the habit of double-checking the fuel pump before you use it every time you fill up at a petrol station.
Remove distractions – put your phone away, turn off the radio and take your time when at the fuel station. Mistakes are more likely to happen when you’re distracted or in a rush.
Place a ‘petrol’ or ‘diesel’ sticker on your fuel cap – this will be a visual reminder of which fuel to use.
If you have a diesel vehicle, buy a different-shaped filler neck – this will make it more difficult to insert the smaller petrol nozzle by mistake.
Ultimately, if the worst happens and you do fill up with the wrong fuel, we hope that these tips will help limit the damage done and get you back on the road in no time.
We’re here to help, so if you think there might be something else wrong with your vehicle, get in touch with one of our technicians at your local Eurorepar car service centre for friendly, expert advice. Find your nearest centre here.