Posted 26th Nov 2022
Hi I have accidentally put 0.14L of unleaded in my diesel kuga but then filled up with 34.43L of diesel, the filling station said it will be okay as I have filled with diesel, I drove the car home with no problems but should I be worried?
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  1. Avatar
    If it was the other way round adding diesel to petrol its a big no no, but with you adding such a small amount to petrol you'll be fine
    Thank you was beginning to panic a little 
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    Never know why car manufacturers & fuel stations can't make it so a diesel pump will only fit in a diesel tank & for petrol vice versa.Then nobody would have this problem again.
    My father's ford had a device in that only opened when the correct diameter nozzle was inserted. If you need to top it up from a jerry can you have to push in a plastic nozzle with a funnel end that was provided in the boot.

    I would guess many/most petrol stations would have number recognition cameras because of drive offs, and it ought to be possible to have a system that uses the cameras to identify the type of fuel from the registration details and which pump the car goes to and prevent the driver accidentally filling up with the wrong fuel unless he overrides it to fill a jerry can.
  3. Avatar
    It'll help clean injectors and egr if nothing else.

    That small amount wouldn't make any difference to anything. Probably more moisture than that in tank anyway.
  4. Avatar
    Years ago I half filled my diesel 306 with unleaded.
    Didn't notice until the engine began spluttering profusely, I topped it up with diesel at the next station to make a 50/50 mix, and it recovered just fine.

    I'm sure modern diesel engines are a lot more fragile due to all the electronics for minimizing emissions, but 140ml in a full tank is practically nothing. I wouldn't worry.
  5. Avatar
    You'll be fine with that ratio and that way round.

    You've got a 99.95% diesel.

    A mechanic once told me he adds a litre or 2 of petrol do a full tank of diesel to cars with injector problems. Apparently it helps clear them out. I've not tested the theory!
    Thank you 
  6. Avatar
    That small amount does not matter, greater quantities need to be removed to avoid serious damage.
  7. Avatar
    I thought Fords had easy fuel caps so you couldn’t fill up with the wrong fuel
    You can't put diesel in a petrol but you can put petrol in a diesel
  8. Avatar
    It shouldn't matter.
    I use to know some who use to put about £20 petrol mixed with his diesel claiming it would clean things. I'm unsure of the truth or science behind it though
  9. Avatar
    Did pretty much exactly the same as you did some 4 years ago in my 2015 diesel Tiguan. Have a couple of vehicles petrol & diesel, started filling on autopilot and immediately realised my mistake. Did what you did and diluted the petrol out. Absolutely no problem since.
  10. Avatar
    My seat has a mechanism that won't allow this, I presumed all cars had !

    The nozzle HAS to be the exact size of a diesel, or you can't put it in.... As I found when I needed to use a can
    Handy hint, keep a 6in length of 25mm electrical conduit in the boot !
    (it's an exact fit for the tank to open)
  11. Avatar
    Sure years ago in Germany Mercedes use to advise a very small petrol to diesel addition to stop diesel freeze in extreme cold.Just searched and found that you can get winter diesel and summer diesel? never knew that.
    It's due to Diesel solidifying/waxing in the cooler temps.
  12. Avatar
    Should be fine, You could run it down to half a tank for the next few fills and refill, just so it continues to dilute it etc.

    The main issue with petrol in diesel is the damage unburned petrol can cause to the cat and dpf. It tends to ignite and destroy them! (edited)
    Diesel is a lubricant and the high pressure fuel pump is lubricated by the fuel that it pumps. If you put a lot of petrol in then the pump can lose lubrication and you can end up with a siezed pump but also small fragments of metal from the pump getting into the fuel lines and the injectors.

    You do need a fair bit of petrol in it though. I think expensive problems were when people filled up an almost empty diesel with petrol and then drove off.

    Dealers often wanted to replace fuel lines and injectors just in case £££££
  13. Avatar
    0.14 liters is nothing , you'd probably be fine putting 0.14 liters of orange juice in it. On a more serious note diesel is a problem in petrol engines because diesel isn't flammable as a liquid and fuel gets ignited as a liquid. Petrol isn't so much of a problem in a diesel engines because fuel gets injected as a vapour, and both petrol and diesel is flammable as a vapour, but petrol doesn't lubricate like diesel so puts more wear on the engine, but 0.14 liters of it isn't doing anything. (edited)
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