Petrol in a Diesel car - Help :(

Silly me accidentally started filling my diesel car with the wrong fuel tonight. I put in 4.5 lites of petrol before I realised. Then I decided to fill it up completely with Diesel to try and dilute the petrol.

I've driven 15 miles so far and it didn't seem any different.

Anyone any idea if I am going to ruin my engine? Should I get it drained or should I risk carrying on?

It's an old car, 2006 Peugeot 206 1.6 HDi so I don't mind taking a chance.

 

Don't drive it any further just yet!

The fuel itself lubricates components within the fuel pump, tandem pump and high pressure fuel rail, and petrol dilutes that lubricating property which essentially means that these components are running without effective lubrication.

If you wanted to be 100% sure, then the fuel system should be completely drained, including the fuel lines etc, and fuel filter replaced - - however, this can be a VERY expensive process.

Partly a saving grace is the fact that your car will not have a DPF or similar, and is unlikely to have much more than fairly basic ECU wizardry, which means that there is no filter to clog or overheat and no computer second guessing the fuel mixture and trying to make it run cooler.

If you don't want to go to the expense of draining the system, then there are a few steps you can take to mitigate any damage - the first being to top up very frequently with diesel for the next wee while (every time there is a space in the tank, go back and re-brim it, this will further dilute the petrol and reduce the lack of lubrication); the other thing you can do is to add 2-stroke mineral oil (don't use the synthetic stuff) at a rate of approximately 300ml to a 70 litre diesel tank - this will reintroduce some of the lost lubrication and should hopefully cover you.

DO NOT be tempted to dismantle the fuel rail yourself, and the HDI stands for High-pressure Direct Injection; the fuel is at such a pressure in the fuel lines that it could cause you serious harm if you do not de-pressurise correctly.

 

Make, model, age and fuel type?

 

Nice

If the Morrison's fuel isn't of the 'super' unleaded variety, that could almost certainly be the cause. I'm not certain, but I have a feeling that your engine was one of those that was designed to run on the 99-RON fuel (like a lot of VW & Audi cars), so running it on the standard stuff will cause it some problems as the ECU map isn't set to match the fuel, which in turn causes problems as the fuel doesn't burn as hot.

Stick a tankful of V-Power in it next couple of fill ups and see if it improves.

EDIT - somewhat counter-intuitively, it can actually cost you more to run a car that wants 99-RON on a lesser fuel, as they fuel consumption tends to worsen when running on the lesser fuel.

 

Thanks for the advice folks.

I've been googling and this subject seems to crop up on forums a lot. Most of the threads I've read seem very inconclusive (and quite often end up with big fights on sites like pistonheads ).

Obviously the safest bet would be to have it drained - but I'm willing to take a chance. I'll stick some two-stroke oil in as FC suggests and keep my fingers crossed.

 

It might also benefit from a bit of an Italian tune-up - I know my Scorpio used to love being driven as though I had nicked it.

BP Ultimate is another super unleaded if that is easier to find, or I believe Tesco do one too. Failing that, I would look at the simple things first (fuel filter, air filter, plugs, coil packs etc)

 

Have you got an opinion please @longk ?

 

This is the stuff you need - low ash is the important thing also.

There is also a school of thought that putting 2-stroke in with diesel on every fill up is beneficial, but only on non-DPF vehicles. Google that and you will see similar fights to the ones about petrol in a diesel

 

It was yes - but therein might lie an explanation..... Has the rough running started since the service?