Should You Worry? Petrol in a Diesel Car in Breedon on the Hill
Provided it hasn't been started, worry far less than you probably are. Until your ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank simply waits there and does no harm. Which means the truthful reply to that first Breedon on the Hill question — "have I wrecked it?" — usually no. Leave the motor off then call Petrol in Diesel — that keeps it that way. The remainder of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to your engine
On its way through a motor, diesel has two jobs. It lubricates to begin with, and only then does it burn. What stops the surfaces inside the high-pressure pump and the injectors from wearing against each other is your diesel flowing through them — they're designed to extremely fine clearances.
Of those two tasks, petrol manages the first poorly and the second never. It is thinner than diesel and removes the lubrication the fuel system rests on, so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the rattling comes from.
Seen together, they show the shape the issue has. It is circulation that causes the damage, not contact. Any tank with petrol in it is a fuel fault. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem starts.
Breedon on the Hill, petrol in a diesel: four situations, from mild to significant
Fuelled up, never started. The best case there is. Being on a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol held in the tank alone, it is emptied and flushed on the spot, and nothing more is needed.
A moment's running, or merely the ignition on. Petrol has come out of that tank and got to the fuel filter and the fuel lines, because the fuel system has been bled. That's usually still a straightforward job — a drain, a flush, and the fuel filter seen to.
Those few miles driven meant your pump labouring on fuel diluted by petrol throughout. The work is your tank, the lines, the fuel filter and clean fuel through the entire circuit, and how hard your car was driven matters as much as how far. On the school run to St Hardulph's Church of England Primary School, the distance is short. Very different once more: a trip to Derby, under 10 miles away, or some distance on the M1, under 5 miles from Breedon on the Hill, where the engine never stopped running hard.
Driven on till it complained — clattering, smoke, a lumpy idle, a dead throttle. The engine is telling you your fuel is no longer behaving like diesel. Stop where you are — on the verge on Worthington Lane, at the kerb, down a side road — and don't move it. A car pulled over early very rarely has permanent damage, since the drain and the flush-through, which still go first, deal with it.
What Breedon on the Hill people get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing comes out when you top up — the tank simply carries more of the same blend. Percentage is not how a diesel fuel system copes with petrol, whatever that advice assumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through smaller parts: that's how a current diesel moves its fuel, and so the lubrication matters for more, not less.
This is the one that catches people. Myth: "If it starts and drives, there is no damage done." A petrol engine fed diesel generally won't run, and so the motorist stops and the damage stops with them. Feed petrol to a diesel and it normally fires up, idles and pulls away like nothing happened — all while its pump wears. Running isn't the same as fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an old workaround for a separate fault. None of what petrol thinned is put back by it — and later, your tank still holds that petrol.
The next start sends petrol back round your pump from the fuel lines and the fuel filter, where some of that sits once your engine has been run. That is why draining your tank yourself doesn't leave you sorted — a myth. On top of that, petrol cleared into a can by the road is truly hazardous.
Petrol in a diesel: how does it occur?
It's seldom carelessness, and no one does it on purpose. A diesel nozzle mostly will not fit a petrol car, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and just in one direction.
When routine and your car stop matching, it occurs. A new vehicle, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. Fuelling up in a rush en route to East Midlands Parkway, with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. Throw in a back seat full of children, a phone call or rain, and habit wins.
How to avoid petrol in a diesel at your next fill-up around Breedon on the Hill
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is just a clue.
- Inspect your filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on the first fill in any car you don't know.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key if a house has one of each. So label it.
- Before the nozzle leaves the pump the first time you fill a hired or new vehicle, say "diesel" aloud. Silly, yes, but it works.
- Whilst you are thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a thinner mix, and so stop as soon as you realise — while remembering that the next stage is unchanged. It is still not to crank it.
Petrol already in a diesel in Breedon on the Hill? Start here
Then the order of things is brief. Starting it is out, and so is turning on your ignition. Ask the attendants to help you push it away from the pump if you're still on the forecourt, whether that's Doves Garages Ltd or anywhere else. What went in, about how much, and if it has run: tell us that when you phone 0333 366 0103.
Corrosion and deposits form the issue with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and see its own Breedon on the Hill page.
One petrol in a diesel task in Breedon on the Hill costs more than another. Why?
The four scenarios above are four different jobs, so no single price for this would be honest. The situation itself does most of the work of moving your cost. Where the car is counts too, and whether a technician can safely get to it, after the proportion of petrol to what the tank takes.
Three questions come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. Their answers are what turn a range into one firm number.
About Breedon on the Hill and where it is
Breedon on the Hill is a small village in Leicestershire, situated in the East Midlands region of England, with a population of around 740 people. Breedon on the Hill sits at an elevation of 77 metres, approximately 9 miles from Derby, and is characterised by its predominantly detached housing stock. Breedon on the Hill is close to nearby places such as Tonge, Wilson, and Worthington, and is about 104 miles from London. Breedon on the Hill remains a quiet, rural community with a strong sense of local identity.
Fuel drain cover across Leicestershire, Breedon on the Hill included
Tonge, Wilson and Worthington are among the places near Breedon on the Hill that the same vans work, answering petrol in diesel calls across Breedon on the Hill's DE postcode area. Our engineers drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Breedon on the Hill: still at the pump?
The best place there is, then — that is where you are. Switched off it stays; then phone.