The guy who works at a gas station was filling up for brief moment wrong fuel type in my car until he realized what he did.

I own Citroen Xsara 1.9d, make year 2000.

Before filling the tank which is 60l capacity, I had about half tank full.

The pump pistol filled up petrol 95 for about 5-6 seconds until it automatically kicked off. Then the guy realized what he did and switched to diesel and filled the tank to the full.

After that I drove the car 2-3km.

My question is will this make any problems to my car or is the amount negligible?

  • 9
    I have the same car, so I will assume you are french too. Gas station have insurance for this! Video camera and essence recipes will be needed. A cleanup and a refill will be gracefully paid by the gas station. And if they can't fix it in a good delay, you can have in bonus a 'voiture de courtoisie' mine was a Audi A3. Sep 13, 2017 at 11:22
  • 6
    Help! I've put the wrong type of electricity in my Tesla… Sep 14, 2017 at 14:36
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    @NicholasShanks Are you positive? Sep 14, 2017 at 19:57
  • 4
    @DonBranson: I'm alternating between that or negative, can't remember. Sep 14, 2017 at 23:42

4 Answers 4


The main problems from misfueling a diesel car with petrol stem from the fact that (as Zaid points out) petrol doesn't provide the lubrication effect of diesel fuel and as a solvent it can actually inhibit the diesel that is there from providing lubrication and this can do nasty, nasty things to the fuel pump which can then have knock-on effects to other components - including small shavings of metal (called swarf) from the damage to un-lubricated pump components getting passed down to the engine which can do significant damage to the injectors in modern diesels that run more advanced injection systems such as common-rail or VW's PD engines.

Additionally there is the potential for petrol to eat away certain seals in the fuel system and possibly the fuel lines themselves.

While this all sounds pretty scary the good news for you is that these scenarios generally involve much larger concentrations of petrol in the mix which isn't the case here.

I'm also fairly certain the engine in your car will be either the XUD9 or DW8 which aren't common-rail injection engines but used Bosch mechanical injectors instead (PSA brand their common-rail engines as "HDi" and in the Xsara only the 1.4 and 2.0 diesels in the facelifted car used it). And that small an amount of petrol which has been diluted to about 3% isn't significant enough to do any damage.

If you're wanting to be extra safe or if you aren't going to be using the car much over the next few days then it would be prudent to keep it topped up with diesel to further dilute the petrol.

  • Thanks for the detailed info, I drove about 1000km since the incident and frequently topped up the diesel. The first day on some rare occasions the engine would hiccup, days after that no issues anymore.
    – tolkinski
    Sep 16, 2017 at 6:51
  • Just wondering what if we filled few Diesel into a Petrol engine car ?
    – RRTW
    Apr 15, 2020 at 9:28
  • @RRTW Typically the diesel will clog the fuel filter and it won't start, if you actually manage to start it and diesel reaches the cylinders? Very bad things. Apr 15, 2020 at 9:45

The main concern with using petrol in diesel systems is that diesel is used to lubricate the fuel pump, which petrol cannot perform adequately, which will shorten the useful life of the fuel system.

I think it's fair to assume that in the 5-6 seconds the fuel bowser was able to deliver no more than 2 L of petrol. 2 L out of 60 L is around 3%.

I wouldn't worry about a 3% contamination. The amount should be negligible.

  • 1
    Agreed. The "petrol" will just burn of during combustion with the Diesel explosion.
    – Piotr Kula
    Sep 13, 2017 at 10:09
  • 1
    60L of petrol in a diesel car would be a problem. 2L of petrol in a 60L tank of Diesel wouldn't make a difference. Sep 13, 2017 at 12:24
  • 1
    It seems there is some information on the internet about the amount of petrol you can put in Diesel: misfuel-solutions.co.uk/faq/safeamountofpetrolindiesel.html Sep 13, 2017 at 14:16
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    do petrol and Diesel form a homogenous mixture of 3% or may there be regions of higher petrol concentration in the tank ? Sep 14, 2017 at 13:16
  • 1
    @AndreHolzner as long as it isn't a return-less fuel system the fuel will be well mixed.
    – Zaid
    Sep 14, 2017 at 13:35

This will not be a problem - in fact, some of the older truckers used to add 2% of petrol to the diesel to help in winter conditions to help reduce waxing of the diesel fuel.

  • I believe Kerosene 28 is used in the same way. It lacks the lubricating properties of Diesel fuel but helps reduce viscosity in low (think arctic) temperature conditions. Sep 13, 2017 at 10:46
  • Indeed this is what some road assistance services do - put some petrol in your diesel tank - in Europe if you call them up in winter with your diesel engine stalling in extremely low temperatures.
    – Pavel
    Sep 14, 2017 at 9:29

The petrol will change the burn characteristics but it is minor. If you were concerned about injection system lube you could mix a little (350 ml) engine oil with a litre or so of Diesel and add that to the tank.

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