................... and have just put unleaded in my diesel Citroen C5.
Great timing a couple of days before Christmas. In my defence it was late
and I've been driving a petrol Alfa recently. Anyway now have 26 litres of
petrol in a 68 litre tank, about 38%. Realised when I arrived home, 1.4
miles from the petrol station.
Have Googled and opinions seem divided over whether to siphon as much out as
possible and top up with derv or whether to drain the whole system and just
how much damage it could cause and how quickly. Any constructive suggestions
gratefully received. If I do have to drain it all out how do I bleed the
Please don't just tell me I'm an idiot - I've worked that out for myself.
in my opinion ( and i'm sure others will have theirs )
get as much out the tank as possible, tube down the filler neck or
similar, do they still use the litle rubber hand pump near the engine ?
any way, once you have as much out the tank without going to extremes
such as removing the tank, then brim to the top with fresh derv and
let it tick over for 20 mins, by which time the limited amount of
petrol still in there will be nicely mixed and all will be well.
Well, you won't have to worry about your diesel freezing up this winter :-)
Seriously, though, it's unlikely to do any permanent damage to the
engine. Farmers in this area put up to 25% petrol mixture into their
diesel Land Rovers at this time of year. The most notable result is that
the engine will be a bit smokey.
If you keep topping off the tank every time it gets down to 3/4 full
then you'll soon dilute the petrol enough to forget all about it. You
surely aren't the first person to do this ... and won't be the last
You are not the first, and certainly not the last.
Syphon as much as you can out, or at least a reasonable amount. Then top up
with diesel. A percentage of petrol in the fuel will not be too much of a
problem. PSA used to advise putting some petrol in the tank in very cold
conditions to prevent waxing, though they did say up to 5%.
The problem is that the fuel pump relies on the higher viscosity of the
diesel for lubrication, which petrol does not provide.
It should be possible to add a few litres of vegetable oil to thicken the
mixture. (Or even lubrication oil in small amounts).
It might also be worth draining the fuel filter and refilling.
Do you have a handbook with the car. That will tell you how to prime the
Unfortunately, you don't say which engine, so I can't say how you should
proced in detail.
Brian ( email@example.com) gurgled happily, sounding much like they
were saying :
As long as you're happy to take a gamble on a very expensive new fuel pump.
Before the days of common-rail diesels, such as the HDi.
It ain't going to be a petrol, that's for sure. Which means it's an HDi.
2.0/2.2/1.6 makes no difference. It's a common rail, running around
20,000psi or more of fuel pressure. That Pump Likes Lubrication. Diesel
fuel provides it. Petrol washes it off. Quickly.
So do ALL the engines have exactly the same method for draining the fuel
from the filter etc?
And I think I have already said that the pump needs lubrication which petrol
will not give.
You will not be able to get all the petrol out, but I suggest you do add
some additional lubricant such as vegetable oil, which has a far higher
lubrication level than ordinary diesel. Yes I know it would be avoiding the
Of course you could just take it to the dealer, as a purist would, give them
a blank cheque made out to them, and let them change the fuel lift pump, the
filter and high pressure pump, plus the injectors for good measure. After
all, it's not them who is paying.
1st and only time I did it I put one gallon in an empty tank before I realised.
I didn't start the engine and topped off to the brim with diesel. I didn't have
any problems but you've put a lot more fuel in then I did. you really will
have to syphon as much petrol out as possible and fill up with diesel and
hope for the best. top time of year for that sort of fuckup, nice one :-)
Just to give you another opinion....
I'd drain out as much as I could from every point on the system that I could
then add fresh diesel as much as I could. Each time the tank gets down a
little, say 3/4 or so, then top back up again diluting the mixture down even
As this is an electronic injection engine then it will need something doing.
The control on them is so much more finnicky than the mechanical injection
engines. ( as I have in my car ;-)
I had a passat once and in the handbook for that it stated that the diesel
engines can be run on anything up to 33% petrol mixture, but this would have
been the old mechanical injection models too.
On another point, where are you? If you dont want the contaminated fuel
anymore then I'll gladly take it off your hands, I have a multi-fuel truck
which WILL run on any combustible fuel going - except jet fuel. If you are
anywhere near Aldershot I'll come & take it off your hands !
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