Friday 1st May 2015
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If you've accidentally put the wrong fuel in your car, the first thing to do is don’t panic! If you follow the advice we’re you should avoid a lot of damage. First and absolutely foremost don’t turn the ignition or start the engine.  If you do this will circulate the contaminated fuel and increase the risk of expensive damage.  Putting the wrong fuel in cars is an easy mistake to make, in fact 150,000 drivers do this every year. Our lives are so busy that we can easily be distracted and that is when mistakes are more likely to occur

What you should do:

  • Don't turn on the ignition or start the car!
  • In line with car manufacturer recommendations, if you can, remove the contaminated  fuel and replace it with clean fuel before the ignition is turned on the car started.
  • Contact your recovery service immediately. If you are a member of the RAC you can call their Wrong Fuel Recovery Service on 0800 051 7845.   The AA run AA Fuel Assist and this is available to AA members and the general public.  Call them on 0800 072 7420 or 0121 535 7479.  Both recovery services will come and drain the fuel, flush the engine and refuel for you.

Putting diesel in a petrol engine is much less likely to happen as the standard diesel nozzle is  bigger than the filler neck on modern petrol cars.   A petrol nozzle is much narrower.

Potential damage caused by misfuelling

The amount of damage done to the car will depend on how long the engine was run for after the misfuelling.

Petrol in a diesel car

Putting petrol in a diesel car can damage the fuel pump which has very fine tolerances and operates at very high pressures.  The main fuel pump uses diesel fuel for lubrication purposes.  If you put petrol a diesel car the petrol and diesel mix and act like a solvent, significantly reducing lubrication abilities.  Damage can be caused to the pump through the metal components rubbing together and creating metal particles which get deposited in the fuel system. Switching on the ignition will allow the petrol and diesel mix to circulate through the fuel system and the longer this happens the more damage is caused, creating costly repairs.   For instance, if the debris gets as far as the common rail system you could be looking at replacing fuel pumps, injectors, fuel rail, fuel tank and line filters.  This is why we advise that you don’t turn on the ignition!

Diesel in a petrol car

Unlike diesel, which has to be compressed to ignite, petrol is ignited by a spark generated by the spark plugs. If the car is started the diesel will clog up the spark plugs and fuel system, causing the vehicle to misfire, smoke and possibly stop running. After the contaminated fuel has been flushed from the system, the vehicle should start fairly quickly. You will see smoke until the diesel fuel is burnt off, after this the vehicle should run as before the incident.

How to reduce the risk of misfuelling

  • Pay attention
  • Don’t trust colours (not all stations use the same colour scheme for fuels)
  • Check the size of the nozzle before fuelling.
  • Keep to familiar fuel stations where possible.
  • Try to not have headphones in when fuelling and avoid other distractions, certainly don’t use your mobile phone at a pump!
  • If your car is diesel buy a Diesel Head Device that fits into the filler neck to stop you using the petrol pump.
  • If the worst should happen make sure you have the telephone numbers with you for a wrong fuel recovery service.

It can happen to the best of us – check out this story.  Have you got a misfuelling story to share?  Let us know in the comments box below!