My wife put 6 litres of petrol in the (empty) diesel this morning. the guy at the garage over the road said fill it up and 'should be ok'or full flush £250…
ive driven it just now and feels fine. on call last night(tired) and was just about to by a swift from sam but now i ought to hold on to the cash in case. anyone done the dilution thing and its been fine?

I've put diesel/petrol mix in mine before when it was given to me & topped up with dielel & had no problems at all, but that is a 4.2l 6 cylinder diesel that's 15 years old, not sure I'd want to do it in a modern common rail engine, although probably still would try it to save the £250!

diesel is dnser than petrol so should displace the petrol to top but could also mix it up thus diluting it somewhat. depending on the size of the tank 6 litres is quite a bit. its certainly not as bad to put petrol in a diesel than the converse!! see how it goes

When my wife put petrol in her diesel it spluttered and stopped in a matter of metres, so the fact its still working would make me assume that its all ok.

All they did with my wifes car was drain the tank and run a bit of diesel through it, no filters etc were changed. So IMO if it drives, keep driving. Might be worth topping up with posh diesel once though as it has more cleaning agents in it.

If its a new car under warranty, dont let on to the dealer whats happened!

Might have got away with it, but petrol engines will usually tolerate some diesel more than diesel engines will tolerate petrol. Just make sure she doesn't do it again, or fill the tank with petrol!

My sister in law has done this about three times on quite a young Seat Leon, quite how it still runs I don't know, she's driven it to engine conking out on at least one occasion after mis-filling it.

A mate filled his brand new Audi A6 and was just driving off the forecourt when he realised it was a diesel. Stopped and got the tank drained but it invalidated his warrenty, or at least Audi were really sh1tty about it when his engine died about 3 months later. Not sure if it was a fuel related death.

People have recommended deliberately putting petrol in when it's cold (about 10%) , so I doubt if it's a reasonable dilution there'll be a problem.

Yes, you'll be ok if it's well diluted. Any more than about 10% ish in a modern diesel will be ok I'd guess.

People have recommended deliberately putting petrol in when it's cold (about 10%) , so I doubt if it's a reasonable dilution there'll be a problem. Thats a new one on me!!

10% is a pretty high amount. For £250 i would be tempted to get it flushed. Are you a member of the AA/RAC as they have offers for that kind of thing.

Pal did it recently and he was a similar amount on a tdci ford. I told him to brim it (It already has 50% full of diesel) with diesel and keep it brimmed for the next few weeks in the hope it continually diluted the petrol mix. He has had no issues since.

I put petrol in my diesel van. 1/5 tank diesel left and then full tank of petrol. Drove it for about 20 miles and then started to loose power. Got to a junction and then it just stopped!! Then i remembered what i'd done!!

Recovery bloke said it would of been ok if it was just a few litres of petrol with the rest of the tank filled up with diesel. It just dilutes it and will burn it in the end. Just keep topping the tank up as often as you can (daily) to keep diluting whats left in the tank. Mine cost (the company) £140 to drain, get it all out the lines and dispose of the mixture.

cheers chaps. ill try aa as ive some insurance thing with them. otherwise i think top up and see. its driven 10 miles since the 'incident' ok. the up shot is this def helps with bike later on, esp if my saved cash for a frame has to go on a flush. bike build pass should be issued with no probs.

on the plus side – surely you get brownie points/guilty points from your wife for almost killing the car??

You could add a cetane improver from Halfords, that could keep it going. One issue with petrol is that it lowers cetane value, which is basically a measure of how much power is in the fuel (not quite like octane for petrol).

its unlikely that you'll be able to put diesel in a petrol car as the nozzles are different sizes to stop the above issue. unfortunately, petrol nozzles being the smaller bore of the two makes it highly possible to do what the OP's wife did!

why did she do it?

The main long term issue with petrol in diesel, is the lack of lubrication of the fuel system components.
Personally, provided it's running ok, then don't worry about it, and run it until the tank is well down before refuelling, as that way you get rid of the petrol quicker, rather than diluting it over a longer time.

Might have got away with it, but petrol engines will usually tolerate some diesel more than diesel engines will tolerate petrol

With petrol in diesel, the biggest issue is destroying the fuel system, as if you try to get a diesel to run on petrol, it'll just cough and splutter before dieing. If you were to run a diesel on petrol for an extended time, then you may risk premature upper engine wear due to lack of lubrication, but the fuel system would die long before that became an issue.

With diesel in petrol, the biggest issue is localised overheating of the engine. Diesel burns hotter and slower than petrol, which means that the combustion chamber is exposed to higher temperatures and pressures for longer, which can cook everything within the combustion chamber fairly quickly, as petrol engines are not designed to withstand the extra heat.

One issue with petrol is that it lowers cetane value, which is basically a measure of how much power is in the fuel (not quite like octane for petrol)

Cetane is a rating of how easy a fuel is to ignite. The higher the cetane rating the easier and generally slower the fuel will burn (whereas octane is a measurement of how hard a fuel is to ignite). It is only vaguely related to how high the calorific value of the fuel is.

If you have a newer common rail or VW PD engine then change the fuel filter at the very least. The neat petrol can in some cases attack the element in the filter. If the vehicle has a lift pump in the tank, check the filter for fine metal particles.

Note that most of the VMs recommend a new tank, fuel lines, pump and injectors. (They are taking the P%ss as usual).
Hth
Marko

Why not drain the tank yourself?

Most modern-ish cars have very easy access to the top of the tank, diesels especially. It's usually inder the carpet under the back seat. Pop the lid off, syphon the fuel out and refill with fresh diesel.
Maybe even ring a dealer (Not YOUR dealer if it's still under warranty! 😉 ) and ask how to do it. I would! Well, in fact I have, but for a different reason!

Seriously, it shouldn't be too hard…. 🙂

Its not the actual Petrol in Diesel running issue you should worry about:
With modern Diesels (Common Rail) the High Pressure pump produces around 1600 – 2000 bar of pressure, as you can possibly imagine the tolerances within the Pump are minute/very small……. to that end it relies on the quality of Diesel to lubricate the Pumps moving components during operation……… If the Diesel is diluted down (as a result of Petrol contamination) the Lubrication quality is drastically reduced, it isn't now you'll have a problem but the future could get very expensive, worst case is usually new: fuel pump £800, new injectors £600-£800, new fuel pipes & the actual time for someone to do it…………

BMW say in the event of a Customer putting Petrol in a Diesel and the vehicle is run you should replaced all these as a minimum to ensure the Warranty is still valid, cost is about £4000….. Ouch

to be fair she was a little stressed covering for me on the early school run, as id been on call in the night. just spoke with the dealership and the spanners there seem to think the top up trick should do it and a filter change soon. ill try my luck with the aa also. phew sam has kept the bits for me, so build will be on at the end of the month..sweet. reckon id get away with building this one in the front room while watching the world cup.

If it's under warranty, then don't call the manufacturers breakdown, and don't take it near a dealer.

Doing either of those means it'll be recorded as a contaminated fuel breakdown, meaning they'll void any remaining warranty unless you spend copious amounts of money replacing bits.

no warranty issues here. 10 yr old citroen hdi!

it will be fine, i used to have a T4 and have heard people recommend putting a bit in to clean it out, so as long as as you filled the rest of the tank it will be ok.

Don't need to get it flushed. Just top it to the brim with diesel. Take it for a country spin (mixes it all up :-))

Might be some whitish smoke on start up for a couple of days but nothing major. My mum filled mine up from empty with about £25 quid and I got away with brimming it. Wasn't the quickest at starting in the mornings mind you!

It is only vaguely related to how high the calorific value of the fuel is

Should have worded my answer more carefully. Cetane number relates to how much power you will get from the fuel.. performance and to a lesser extent economy will be improved up to a cetane number of about 60, normal diesel is at least 51 and BP ultimate is at least 55.

Cetane improver helps if you are using petrol to thin out veggie oil in your motor, because the petrol reduces cetane number.