Putting Wrong Fuel in Car: What You Should Do

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Have you ever heard of the Charge of the Light Brigade? One of the most infamous military blunders in history, a miscommunication saw a section of British Cavalry accidently launch a full head on assault on a well dug in Russian Artillery position during the Crimean War. The results were about what you would expect when horses attack guns.

Or did you hear about the guy who made a measuring error of 4 microns – yes, 4 tiny microns – that totally threw off the Hubble’s telescope’s ability to, well, be a telescope. NASA didn’t notice the error until the Hubble was in orbit – and repairs cost in the region of $50 million to make.

Looking at those – just a couple of notable screw-ups plucked from an endless list – could help to put into perspective the far simpler mistake of putting the wrong fuel into your car. But at the same time, you can’t hitch a lift home on the damn Hubble Telescope can you?

That’s why putting the wrong fuel into the car can seem like a real disaster – it’s because it’s personal. In this article, we’ll take a quick look at this classic car screw up – especially how to deal with it effectively and stop it keeping your car off the road for too long.

wrong car fuel

Image source: carwow.co.uk

Why is it a Big Deal?

Before we get to that though, first up we should take a quick look at why it’s bad to put the wrong fuel into your car. So why it is a big deal if you’ve accidently poured in the wrong fuel?

Well it’s because diesel and petrol (AKA gas), despite having common origin points and similar end uses are also somehow completely different in the way in that they interact with the engine and the fuel system as a whole.

Diesel, in addition to being a fuel source, is also a lubricant. That means that as it makes it’s way though the fuel system and is burnt up in the engine it is also helping all those moving components (and there are a lot between the fuel tank and the engine firing) to move smoothly.

Petrol on the other hand is a solvent. That means that it does not lubricate at all – quite the opposite in fact. That is why you have to keep a petrol engine topped up with engine oil for extra lubrication.

That means that when each fuel enters the wrong system it can have catastrophic results. The Diesel engine is not lubricated enough by petrol, and the petrol engine cannot fire with the diesel fuel, as it has a completely different combustion temperature.

Long story short, it’s like feeding Kryptonite to Superman – it’s the wrong stuff to be putting in there, and it’s bad news all round.

First Response

What you do in the first couple of minutes after you realize your error will have a huge impact on how easy it is going to be to solve this issue. So settle down, bite on a bullet and carve this mantra into your arm with a rusty piece of barbwire so you don’t forget it.

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Hold on.

Ok, our legal department has just handed us a piece of paper requesting we don’t instruct you to carve messages into yourself. Fine, cry babies. Just remember this golden rule then, because it is very important.

The first thing to do is to do nothing.

Absolutely nothing, diddly squat. Zero, zilch, nothing.

You see, here is the issue. Many people, when they realize what they’ve done, the first instinct is to get out of there. They think, crap crap crap, I can’t believe I just did that, this is so embarrassing! If I can just get out of here, I can sort this out.

And then they turnthe key in the ignition and try to drive off.

Do. Not. Do. That.


As soon as you turn the ignition, the damage starts to spread. The fuel pump is now pumping up the fuel, it is coursing through the pipes that take it from the tank to the engine, and it is now in the engine screwing everything up.

If you leave the engine off, the fuel will stay in the tank. That means the repairs are (hopefully) limited to that single piece of the vehicle instead of the tank, the fuel pump system plus – worst of all – the engine itself.

Handy Checklist of Calm Proactive Action

Here’s what you should do then. Ready?

  • Have a good scream. Seriously, dropping the wrong fuel into the tank is So if you want to, sit in the car, punch the steering wheel a bit, scream, let out some rage. Just make sure any kids or pets are removed from the vehicle, and the windows are rolled up.
  • Go back into the gas station. We’re assuming that you’ve got your gas from a gas station in the traditional way. If you’re currently in the process of stealing your gas – perhaps from a truck stop or parking garage… well, you’re on your own here.
  • Back to the Gas Station. Where were we? Oh yeah, we’re in the gas station now. Explain to them what has happened. They might have guessed if they could see you through your side window screaming and hitting the steering wheel. Don’t be embarrassed either, this is a common mistake that happens all the time – you may not even be the first person they’ve seen do it that day.
  • Roll it or park it. Once they understand why you can’t drive off, find out if they are happy for you to leave the car where it is, or if it needs to be rolled off to a parking bay. If the former is ok, drop down to the next section. If they need it moved, do not start the car, even just to shunt it forward a few feet. Ask for their help (or call a pal to come up). Release the parking brake and push the car out of the way if at all possible. If you drive a Humvee and can’t push it, now would be a good time to consider the life choices that led to you making that dumb decision.
  • Go back into the gas station. Grab yourself a can of coke or a candy bar. You’ve earned it, it’ll make you feel a little bit better.
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putting wrong car fuel

Image source: carkeys.co.uk

Fix the Problem – The Easy Way

You’ve stopped panicking, the car is secured. The next stage will be to repair it. There are a few ways to tackle this, but the main issue is to get that fuel out of the tank as quickly as possible.

To our mind there are three options:

1) A mobile drain.

There are companies out there who can bring specially adapted vehicles straight to your car. The vehicles have powerful pumps onboard that are hooked up to the fuel tank. They suck out the bad fuel and store them inside empty tanks mounted in the vehicle. The good news is this is a relatively fast procedure, and it’s also pretty cheap. The bad news is they are almost always not equipped to replace your pump and filters there and then. They will however often flush the fuel lines with the correct fuel, and also add a special solvent that will dissolve the remaining incorrect fuel.

2) Tow and Garage Drain

The alternative to roadside repairs is for the vehicle to be towed or otherwise removed on a truck and taken away to a garage for repairs. This could be the best option if the vehicle has already been started and the fuel has entered the pumping system and the engine. The downside to this is that it will be more expensive than a simple roadside repair, and it will also take a fair bit longer to be completed. The plus side is that the garage has the tools and the time to properly assess the damage and replace any parts there and then. That removes the risk that is found in the mobile repair option of missing some fuel in the system that carries on doing damage.

3) Tow and Do It Yourself

You’ll still need a tow or some other way of getting the car away from the gas station. However, some people may like to instruct the tow truck driver to take them straight home, instead of to their local garage. Oh boy.

Insane in The Drain 

So, you’ve got the tools and you’ve got the talent. Or, you think so anyway. You then have two ways to remove the fuel.

1) Siphon

For the love of all things holy, please buy a siphon kit. That is not, by the way, a hose and a mint. A siphon kit is a long piece of hose with an air pump built in. Make sure you get a spark free model (of course) and remember that you will need to siphon the gas off into a suitable container and dispose of it properly.

2) Gravity Drain

Some cars have a drainage plug on the fuel tank. It will be located on the underside of the tank, so you’ll need to crawl under the car or raise it up a little. It will usually be held in place with a small bolt. Place something like a drainage pan underneath and undo the drainage plug with a spanner. The hole is usually pretty small, allowing you to control the drain. If the pan fills, replace the cap to stop the flow, remove and empty the pan, then pop it back underneath.

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What Next?

Either of these methods will remove the bulk of the incorrect fuel from the car, and if you remembered not to turn it on then the engine at least should be fine. You should definitely flush the fuel system with the correct fuel, and you may need to replace the fuel pump and fuel filters, even if you didn’t turn the car on.

Any drop in performance or any sign that the engine is not running smoothly is a clear indication that at least some of the incorrect fuel remains in the system. In that instance, you could try draining and flushing again. However it might be time to bite the bullet and take the car into a pro mechanics shop.

fuel for cars

Image source: cizgirentacar.com

After the Event

Eventually, your car will be repaired and you’ll start to forget that hassle that was caused. Our advice is to not forget! There are few things that you can do to make sure this doesn’t happen again.

  • Color Stickers – It may seem childish, but you will often see commercial vehicles with coloured stickers placed on or near the gas cap cover. They will usually be green for petrol and black for diesel. If you’re worried about putting in the wrong fuel again, consider copying this. You can place it on the outside of the flap, on the inside – whatever works for you. Like we said, it may sound a little childish – but it is also a cheap but highly effective way to avoid going through this problem again.
  • Adaptors – You can also pick up cool little plastic adaptors that fit into the fuel tank hole. The nozzles of petrol and diesel pumps are often different shapes and sizes, and placing this adaptor in the hole means that the tank will only accept the correct shaped nozzle. Again, this is a very cheap but effective solution.
  • Carve it – Or you carve the type of fuel your car takes into your arm, that way… oh yeah, we’re not allowed to tell you to do that. Do not carve the fuel type into your arm.


So that’s about it. Hopefully we’ve shown you that it is not the end of the world if you accidently add the wrong fuel type to your car. Just remember to stay calm, to avoid turning the car on if at all possible and to get the incorrect fuel removed as soon as possible and you’ll be fine.

Happy driving, folks!

Originally posted 2023-09-06 02:26:22.

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