What to do if you have added the wrong fuel

Wrong Fuel in Car

Believe it or not adding the wrong fuel to a car has become more common. The AA released that over 150,000 cases of mis-fuelling occur every year and is gradually increasing. It’s the most widely talked about and feared cause of breakdowns across the UK and Ireland, We have put this guide together to address what are the myths and facts of filling up with the wrong fuel. We will provide clear solutions, live tests and contradicting theories from mechanics which can help us educate ourselves should we ever be unfortunate enough to find themselves in this difficult situation.

Be aware that this type of breakdown is not covered under your warranty.

OK you’ve made a mistake, what should you do?

BEST PRACTICE! DO NOT START THE VEHICLE! If you are at a filling station forecourt and just realized what you have done the key is not to panic. This is not unheard of by service station staff and the reputable petrol stations have seen this numerous times before and have had experience dealing with similar situations and may be in a position to offer a local service whether it’s a mechanic or a breakdown recovery service that can get you to a local experienced mechanic. To avoid embarrassment of ‘’forecourt rubber neckers’’ have your car pushed into a parking bay and away from the fuel pumps. If you get an inexperienced staff member at the petrol station you could use the search engines or automotive websites such as www.everythingmotoring.com, Golden Pages or Yell.

Can the vehicle be driven?

There is evidence that the car will drive for a short period before the incorrect fuel is distributed and causes the damage. We would advise that under no circumstances try to drive your car as you will cause more damage reflecting in additional unnecessary costs. If you start the engine, or try to drive the vehicle, the wrong fuel penetrates further into the vehicles fuel delivery system and associated ancillaries. You may get a mile or so up the road if you are driving on diesel so don’t just assume that the car has broken down think carefully whether you actually added the correct fuel. If you realize that you have added the wrong fuel and have driven a very short distance you might be lucky enough to dilute the wrong fuel with a full top up of correct fuel, this will depend on how much incorrect fuel you added initially. This shouldn’t happen if you are driving a petrol car as a petrol engine should cut out after a few seconds.

Should I turn the engine?

Only in extreme circumstances for example unlocking the steering or if you drive an automatic and need to turn the engine on to select neutral gear in order to move the vehicle to a safe area or parking space. It is important to remember to switch off your engine once you have selected the neutral gear or unlocked the steering as this will circulate the incorrect fuel and cause serious damage. There will be some old original fuel still in the line which will allow you to start the car without causing any damage to the vehicle if the engine is only turned on for this purpose.

Will the filter need changed?

It is advised to have the fuel filter changed after adding incorrect fuel. An experienced technician will flush the system before restarting the vehicle. Once the mechanic has drained the system and flushed it with the correct fuel the car will have to be taken on a short test run to get rid of any contaminated fuel left in the filter. Because fuel filters are inexpensive parts generally averaging around £40 and easily fitted within an hour there are minimal labour costs making it a worthwhile investment.

If your car is still under manufacturer’s warranty please be advised that by having someone other than the manufacturer / franchise that you purchased the vehicle from complete the work could invalidate your warranty.

Will it make it worse if driven with incorrect fuel?

More than likely! How much depends on the age of the car. Modern diesel engines ancillary equipment is strong and the mechanics shut down quickly to avoid further damage so usually after a couple of miles as mentioned the engine will shut down and damage will be limited to almost non-existent. Petrol vehicles on the other hand usually don’t start but if they do they will run for a minute then cut out.

Being a thicker substance, diesel is not as combustible as petrol. When the diesel is removed and flushed and the car restarted, there will likely be excess smoke which should eventually burn off. Older vehicles will more than likely incur more damage and will be harder to re start. Fuel pump and catalytic converters are usually the parts affected with older vehicles.

It is advised to act quickly in order to minimise the damage risk. Some garage services businesses offer a mobile fuel drain unit which should be your preferred option as a vehicle might sit about for several days before work commences.

What should I expect to pay?

Prices vary depending on locality, time that the incident occurred, availability etc. Common sense must prevail don’t go with the first quote just because you are eager to get your car back on the road. Ring three similar businesses even if they are outside of the area and take an average as a guide to make sure that you aren’t overpaying for the service. Our research tells us that you could pay in the region of:

Mobile callout and drainage – £170.00 to £300.00.

Vehicle moved to a dealer for drainage – £300.00 to £400.00.

Main dealer recovery for a vehicle under warranty – £2,000.00 – £10,000.00.

What is the process to correct my mistake?

This all depends on the type of mechanic that will be completing the work. As we mentioned above, the option of main dealership is a lost different from a roadside drainage. It will likely involve replacement of fuel pipes and the fuel tank, along with filters and pumps and even injectors. If it is brought to a local vehicle repair shop they may fit a replacement fuel filter as well as drain and flush it. The mobile callout out guys will not likely carryout part replacements. They would usually just use a fuel additive on top of draining and flushing, which can help the system to lubricate more effectively and help to more any remnants of contaminate fuel. More advanced additives can also boost cetane levels increasing combustibility.

What’s the damage?

Each case is different and has to be taken on its own merits but we know that the main components and elements of the drivetrain affected will be:

  • Fuel pump
  • Contamination of fuel tank
  • Injectors
  • Catalytic converters
  • Post mis-fuelling, carburettor service
  • Valve guides and valve seats.

See what happens when you add diesel to a petrol car.

Fuel Specific - how they perform differently

Petrol in diesel. Experts say that if it can be avoided do not to start the vehicle. A diesel car is not as sensitive to receiving petrol as a petrol is to receiving diesel. If you drive an automatic car, a push button electric start or one that doesn’t have a good old fashioned key, and you must start the car in order to take it out of park and release the steering wheel lock, a matter of a few seconds with the engine running is highly unlikely to cause any major concerns. It should just be a matter of getting a reputable mobile fuel draining company to drain the vehicle immediately, and no further action should be required. We would recommend that a quality additive be run through the system to get rid of any remaining contaminated fuel. Once this has been removed the vehicle can be re started, and for extra peace of mind the fuel filter should be changed within the next few days.

Diesel in petrol. Once again, we recommended that the car is not started. In this instance a mobile fuel drainage company can attend the scene of the breakdown swiftly, should be utilised to remove the diesel. After this process has been completed the vehicle should restart. It will require a thorough flush through the system once the drain has been completed. This process will normally take at least 50% longer to carry out than if working on a diesel engine equivalent. However, once completed it should start quickly, initially producing a fair quantity of smoke while any diesel residue is burnt off.

For further information, check out this video

How to drain your car fuel tank

The removal of contaminated fuel from most vehicles should be carried out by an expert but if you want to save money and thisnk that you have the skills to complete the task yourself here is a how to video to guide you through the process.

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