Here is a list of the wrong fuel questions we get asked – on or before nearly every job!
Q; I drove my diesel car for 2 miles on petrol after I filled it up, then it just died on me. Will it need to be repaired ?
Answer; you didnt drive it for 2 miles on petrol whats more likely is you drove it for 2 miles with petrol in the tank.Once the petrol made its way through the low pressure sender pump, thru all the fuel lines, up to and through the filter (holds about a pint of fuel), through the hoses to the high pressure pump, thru the pump, into the common rail resovoir, and finally into the high pressure lines into the combustion chamber, that’s normally the exact point that the engine stops turning, and in fact you will find you maybe got about 20 yards on petrol, which is the time it took for the engine to stall. The good news is, this isn’t as catastrophic as you might think and there is a simple, effective solution in a mobile fuel drain – a service we provide all over the country and we attend most call outs with 50 minutes, 24 hours a day. there are many different things that can happen with misfuelling, I have covered most of them below.
This is a typical case of a car that was driven for about 20 miles on the wrong fuel. We got the call out when the owner couldn’t start it in the morning, and then realised she had misfueled it the day before. This car had been drained from the tank and the fuel system flushed through, if you listen in the beginning the sound may be familiar to anybody who has tried to start a misfuelled car. But as the car starts, it quickly goes back to sounding normal. 99% of breakdowns caused by misfuel are this easy to fix. Humble apologies for the quality of this video, I took it on my phone, because it was the camera man’s day off!
Q; What does petrol do to a diesel car's fuel system?
Answer: This picture (below) is the suction line I use to remove wrong fuel . this was taken when doing a job that had 50 litres of petrol in a diesel mini, this was being taken from the fuel tank as the car had not been started. this hose is full of fuel, about 70% petrol, 30% diesel.
This is a picture of the same hose, the car was a Diesel VW Polo, it has been fill’d with 90% petrol, and 10% diesel, the car had been left overnight after loosing power and being towed back to the customers house, the suction line was attached to the high pressure pump inlet, as you can see the fuel has gone black, this is becuase the petrol has desolved rubber in the fuel lines, this car sat for a day with a very strong mix of petrol, it had also been driven until failure, the dark colour is a mix of rubber and plastic that has dissolved in petrol (fuel hoses are made type specific to reduce costs for car manufacturers,i,e diesel for diesel hoses only and petrol in petrol hoses only), I would not expect this to have done the car any real harm over an 18 hour period, just a microscopic layer of fuel line has been stripped off from the inside, these lines are fairly thick so a short bit of contamination once is fine, if you do want to make a habit of misfuelling regularly and leaving the car sitting for days with the wrong fuel in it you will eventually need new fuel lines. and plastic fuel components
Q; What happens to the fuel once we take it out
Answer; at the end of the day (or during a very busy day), I unload all of my mixed fuel into 220 litres drums, at our garage, (a licence is required to store mixed fuel from the enviroment agency), the mix is collected every 7 to 10 days by a garage services company, these are the same guys who take away used engine oil, brake fluid etc.. from garages everywhere. the mixed fuel is batched seperetly and in-between me and all the other companys that offer this service, I would guess that there is between 50 to 200 thousand litres a week of mixed fuel “made” in the UK per week. – once it is batched up into viable quantities usually 28.000 litres (tanker load) it is refined in one of the main refinery’s using a distillation process – identical to the one used for making crude oil, the petrol diesel mix seperates at 60 – celsius, i,e the petrol fumes off, it is then condensed and seperated, from what I have heard this is done twice to get a proper result, I would assume that the mix would then go back into the supply chain and be used as it was originally intended!
Q; I put the wrong fuel in - have I damaged my car?
Q; My car conked out, have I wrecked it?
AnswerNo, as above “conking out” is your engines way of saying “I am not moving untill you get the wrong fuel out of me and the right fuel in”, I attend many “conk outs” “died” “made horrible noises” etc.. once they have been drained down , 20 litres of correct fuel put in -and the system fully purged upto the high pressure pump fuel inlet – then , they all ran fine afterwards
Q; My car has a common rail pump, are you sure its going to be fine?
Answer; YES!, the vast majority of new diesel cars have sophisticated common rail pumps, we attend them day in, day out what I have written above applies specifically to common rails.
Q; Whats worse, diesel in petrol, or petrol in diesel?
Answer; the wrong fuel in varying quantities does different things, petrol in diesel will stall it, or depending on the mixture it might just still run, albeit sounding like a bag of spanners, – with reduced power Diesel in a petrol car will make it lose power, and run flat. The worst case scenarios (and these are the WORST) are;
1) petrol in a diesel pump will eventually damage the pump (If you are unlucky enough to get a mix that just runs) , if you have not noticed it, and are completely oblivious to the car’s behaviour, you would also have to do a fair ammount of driving with a heavy foot, this would require a new common rail pump, piezo injectors and fuel lines, the high pressure fuel pump which operates at 28 oddd thousand PSI of pressure and is a highley enginerd unit relies on diesel going thru it to provide lubrication, petrol does not lubricate, in fact it has “anti lubricating” properties, hence why petrol is good for cleaning out oil stains. what happens is the inner working of the high pressure pump start chaffing metal grinds on metal, this destroys the pump, then the metal chafe gets drawn thru to the piezo injectors and ruins them as well, now before you go and sell a kidney to pay for a new diesel pump and injectors, please read the read the rest of these FAQ’s because full scale damage like this is very very rare.
2) diesel in petrol worst case scenario, the diesel will enter the cylinder and not burn, it will slide past the piston rings, into the oil sump and therefore the cars oil system, this will increase the oil level, to a point that could cause total engine failure, i.e mangled rods, bent pistons, complete block failure, or the thining of the oil can reduce lubrication to the engine and it could suffer from a full seizure/big end failure/ruined propshaft. Again this would not be an easy thing to do, the car would be very low on power and not running right, you would have to do a good bit of driving in it to achieve the above.
Q; Land rover/mercedes/bmw/audi etc all insist I bring it into the garage for a full drain and it will cost ££££££££££ what should I do?
Answer: main dealers and “tooth sucking garages” will sometimes take a misfuel case for all its worth. I have heard of people having misfueled cars collected by main dealers (these cars had not been started and were collected from the petrol station forecourt) and then the insurance company picks up a tab for 5 or 6 thousand pounds for parts that absoloutley dont need replaced, (and I would suspect never get replaced), this is all very well untill you lose your no claims bonus and when you trade your car in eventually you have to explain why it had so much major work when it was brand new.
Q; But the maindealer says I must bring it in otherwise the engine and pump will be ruined
Answer; I’ve got a fair bit to say about this, probably the most high profile example of manufacturers being totally inflexible was the Icelandic volcano eruption, and the disruption to flights, it went like this, there was a small amount of ash detected in the air space, as a precuation the authorities asked Boeing & Rolls Royce what was a “safe” and what was an “unsafe” amount of ash for jet engines to fly in, the responce they got was “zero”, therefore all flying was banned. because none of the big engine makers would go out on a limb and come up with a “safe” level of ash everything came to a stop – (until the airlines started flying empty planes round in circles to prove that it was actually safe) Coming back to the automotive industry, the car manufacturers have a similar one policy fits all approach to wrong fuel in cars, , and that is certain things must get replaced after a fuel drain regardless of how much fuel was put in, for how long, or whether the car was driven. They win both ways, firstly they sell lots of parts and millions of hours of labour that wouldn’t otherwise be sold – and secondly they never have to deal with someone claiming warranty if there is any possibility of wrong fuel being used , they know that petrol in small temporary quantities won’t destroy a diesel engine, but they could never say it, because it they are wrong on just one car once… its would be one too many, that’s the manufacturers approach, and the main dealer network quickly caught up with the idea of turning it into a lucrative money spinner and starting milking customers and insurance companies for thousands of pounds.
Q; I've read everything here but the stuff I read on the net and in car forums says otherwise, I still don't know what to do?
Answer; I don’t blame you, I have seen the various discussions in forums on the net – it makes for scary reading if you have put petrol in a diesel car, you will find most of them are repeating threads from older posts, who have re-hashed threads from even older posts, that were written by armchair mechanics , the amount of conflicting information is also a clue as to the validity of the content, there’s a lot of people talking a lot about something they know very little about, I do fuel drains, its my livelyhood, I do dozens every week, I have attended thousands of call outs, I have seen customers who I did fuel drains on after they had driven 10.0o0 20.000 and even 50.000 miles in their cars after putting the wrong fuel in and being drained, none of them had any damage that developed after the misfuel.
Q; I'm in a hire car, should I call them and have them arrange something
Answer. (I dont mind getting a legal letter on this one becuase I know it to be true) I received a call from a man in Canada on Tuesday, last week he was in the UK and misfuelld in a HERTZ rental car, the forecourt attendant gave him my card, before he called me he had a quick look at the rental agreement, it was quite clear that he was obliged to tell Hertz what had happened, so he did, and they sent the AA. his card was then debited for £500 odd pounds, now the AA charge between £100 if they are quiet, to £230 if they are busy for a misfuel (no it is not covered by AA membership), so how did he end up paying £500?, Hertz called the AA and I assume got a whacking corporate discount and had the job done for 50 or 60 quid, they then put the boot in and charged the customer £500, he didnt have a choice in the matter because they had his card details, so if you are in a hire car you could either, call an independent mobile fuel drain company, or if that makes you uneasy – call the AA yourself , and pay for it yourself, you will save a small fortune.
Q; I have read all the above, now I think I will top up with the right fuel and chance my luck will that be ok?
Answer; hmm… I would always recommend a full fuel drain, not because I want your business but because petrol does not do any good in diesel engines, it can corrode rubber hoses and plastic seals that are fuel type specific (petrol and diesel behave differently on different materials, , so the car manufacturers use different plastics and rubber in the fuel system) , as much as I believe wrong fuel will not wreck a car, that is based upon the wrong fuel being taken out as soon as the mistake has been spotted, petrol in a diesel engine will eventually cause problems if not dealt with, but if you are driving an old knacker that will be scrapped when it fails its MOT that is due in a month then you might as well just risk it, but otherwise DRAIN DRAIN DRAIN.
Q; Can I keep the wrong fuel after you drain it, I want to use it in my lawnmower
Answer. there are easier ways of getting out of mowing the lawn other than ruining your lawn mower with a petrol diesel mix, maybe you should feign injury or concrete over the garden. Really misfuel is not worth trying to use, even if you think you have just put 80 quid of petrol in your range rover sport and assume you have a 99% petrol mix, allow me to elaborate.
when you drive a car your fuel sloshes around the tank, (even with baffles) when it gets low and sloshes too much it draws air into the fuel system, this is what running out of fuel feels like, however the tank is not totally empty at this point, it merely cannot supply a constant flow of fuel without interruption, but there is still around 5 to 10 litres in the tank, this changes the sums when you are calculating the “purity” of the mixed fuel, and you will actually have a fair bit more diesel in the mix than you thought you had, allot of people tell me that the “gauge said 3 miles left” and when Í’ve finished the drain and they fill back up they find they got 20 quid more in it that they ever had, and are genuinely surprises how big the tank actually is, that said, if you really feel attached to it and have suitable containers and somewhere safe to store it, then I might just let you keep it, I will expect coffee, biscuits and perhaps a sandwich or two for the privilege.
Q; Are there a lot of idiots/wallies/Muppets who misfuel like me?
Answer; I have met some of the nicest people doing fuel drains, in fact it has restored my faith in humanity! You most likely are not a Muppet, fuel filling pumps are very unstandard and there is no uniform colour coding of pumps, the AA released a snippet a few years ago that 300.000 people per year misfuel, I think the true number is many times that, and the number of people who only misfuel by a pound or so is astonishing, people who lead busy lives or drive more than one car are more likely to misfuel, some older customers joke that maybe they have gone senile – and it doesn’t even occur to them that they have driven a petrol car for 40 years and just got a diesel fiesta because there son insisted they get a more economical car – (and were embarrassed about the 1985 Cortina that mum and dad were running around in), don’t beat yourself up, you most likely live a busy life and have responsibilities that take up a lot of your attention, misfuelling is not the beginning of dementia, nor is it indicative of a low IQ, anyone who gives you a hard time or carries the joke on too long, is probably the sort of person who has a go at everyone about everything, so don’t take it personally, one day it will happen to them too. The “at risk groups” are mothers with young children, (try filling up with toddlers), anyone in a rush, fleet drivers who run a petrol home car and diesel work car, and of course Muppets joke;-)
Q; Does the petrol seperate and float on top of diesel or does the diesel float on top of petrol
Answer; neither, they blend instantly in the tank and it becomes a fairly even mixture, although they are different compounds, (technically speaking the carbon chain on diesel is longer) , they both come from crude oil, petrol and diesel spend millions of years in the ground as one and the same as part of crude, only refining seperates them, and once recombined they will mix together and stay together untill refined.
Q; I have heard of petrol being used as an additive in diesel in colder climates, why?
Answer, yes, it can be used as an ad-hoc winter fuel additive, in remote freezing areas that do not have a well established supply chain of fuel, (think Arctic weather stations), in the UK however we have a very good supply chain of fuel and winter additive is added by the refiners as early as September, the engines that can tolerate a bit of petrol are lower technology diesels, that do not have the high pressure pumps that are found in the cars of today, I would not recommend using Petrol as an additive to diesel, I heard from a skip hire company in edinburgh that used to add petrol into diesel – but they stopped doing it in the 90’s.
Q; My engine management light has come on - what does that mean?
Answer: Engine management lights come on for a number of different reasons, on Volkswagons for example when they have been driven on the wrong fuel and drained, they often take a while to restart sometime 3 bursts of 30 seconds cranking, it is not un-common for the low oil light to come on when it first fires up, it goes off after a minute or 2, engine management computers are not very informative, they either say – “no problem” or “problem”, petrol in a diesel car will confuse sophisticated engine management computers, they are designed to regulate air and fuel flow, air pressure, exhaust pressure, exhausttemperature, ignition timing, all to give optimum performance, economy and emissions, when you put petrol in the tank it throws all the calculations off, some very intelligent engine management units cars will even try to “adjust” to the contaminated fuel, and when they fail as they always do, they will sometimes read a fault, the vast majority of fault codes generated by a wrong fuel scenario are temporary, which means once a fuel drain has been performed – the engine will detect that the conditions that caused the problem are no longer present – thus assumes the problem is solved and the EM light will go out, It is very rare that a light stays on after a fuel drain and restart, this is one of the reasons why I would always suggest a professional drain on a new car, a professional drain will remove as much fuel as is possible, which mitigates possible damage
Q; I put the wrong fuel in, do I need a new fuel filter?
Answer: No you not need a new filter. This idea came about from the “logical” assumption that the filter would be contaminated with condensed amounts of wrong fuel and thus continue to weep wrong fuel into the system, a filter does not hold much fuel – and petrol and diesel certainly do not “condense” 300 to 400 ml of fluid is what a filter holds, the filter is simply a housing, with a cardboard, paper type filament to catch solid debris, a diesel filter has 2 purposes, to prevent water from getting into the engine via a water trap – which needs emptied on servicing or by dashboard warning light sensor, and to stop solid debris from the tank from getting into the engine, diesel and petrol are neither, and petrol does not “sit” in a fuel filter, likewise when diesel is put in a petrol car it does not sit in the system when a fuel drain is performed of a car that has been driven to failure on wrong fuel a flush is done of the filter, this involves pumping the correct fuel through the filter, which purges the filter completely, after a proper fuel drain a filter will be clear of the wrong fuel, I think that this is sometimes used as an excuse by some garages to inflate the price of a fuel drain, the truth is that most fuel filters cost a whopping 4 pounds, and take a lenghty 6 to 8 minutes to change, I have seen garages charge over 150 pounds for a filter change, and If I was morally bankrupt I would be getting in on it to, but the truth is that there no reason to change a filter unless it is due per the service book, that said some people still want filters changed during a fuel drain for peace of mind, which I have done occasionally if the filter is supplied, for the princely sum of a cup of tea and a heap of biscuits, (chocolate).
A very good article on this subject was written by auto express, here is the link here
This was re-hashed by the daily mail here
Q. Who owns Fuelfixer
A. Wrong Fuel company, Fuelfixer Ltd, is owned by the managers of the company, Stuart Guy and Daniel Garside. It is headquartered in East Grinstead, West Sussex. The business was started by Murdo Guy in 2010. Murdo now operates Tubby’s Tyres, based in Crawley.