Should You Worry? Petrol in a Diesel Car in Kirkliston
Far less than you likely are, provided it hasn't been started. Petrol resting in a diesel tank does nothing to your engine until something draws it through your fuel system — your ignition priming the pump, your starter, or the drive on its own. So the honest answer to the first question anyone around Kirkliston asks, "have I wrecked it?", is usually no. Keep it like that: leave your engine off and phone Petrol in Diesel. The rest of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the engine?
On its way through an engine, diesel has two jobs. It protects first, and after that does it burn. The high-pressure fuel pump and the fuel injectors are made to extremely fine clearances, and the diesel passing through them is what stops those surfaces from wearing down against each other.
Of those two jobs, petrol handles the first poorly and the second never. It's runnier than diesel and removes the protection the fuel system hinges on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
Taken together, they show what shape the issue has. Contact does not do the damage — movement does. Petrol in the tank is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors further on.
How serious is petrol in a diesel? Four situations our engineers see in Kirkliston
Fuelled up, never started. The best case there is. At a forecourt, and really only there, that petrol is still confined to that tank — since anywhere else the vehicle was driven to reach it. The task is emptying and purging on the spot.
Ignition on, or started for a second. Once primed, your system has drawn petrol from the tank as far as the filter and the fuel lines. That's usually still an easy job — a drain, a flush, and the fuel filter seen to.
Driven a few miles. Now your pump has spent these miles running on thinned fuel. Tank, lines, filter, then clean fuel run through the entire system: that's this work, and the way your car was driven counts as much as the miles. Driving the kids to the local primary school is one kind of trip. Very different a second time: a trip to Edinburgh, under 10 miles away, or any miles on the M9, under a mile from Kirkliston, where your engine kept running hard.
Driven on till it protested — knocking, smoke, an uneven idle, a dead throttle. The fuel is not behaving like diesel any more, and the motor is telling you. Stop wherever you are — the verge on Main Street, a lay-by, a side street — and leave the vehicle where it is. What comes first is still the drain and flush, and that takes care of it, with long-term damage very uncommon if a vehicle is stopped quickly.
What Kirkliston motorists get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed when you top up — your tank simply carries more of the same blend. The idea behind the guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: a current diesel copes with a bit of petrol. If anything, the reverse. A current diesel runs its fuel through smaller components at higher pressure, which makes the protection count more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most motorists than any other. Diesel in a petrol motor usually means a motor that will not run: the motorist stops, and so does the harm. A diesel fed petrol generally starts, idles and drives away as though nothing has happened, whilst your pump grinds. Being able to run isn't the same as being fine.
Not so: a two-stroke additive lets you to drive home. It is an old fix, supposed for another problem. That petrol is still in your tank afterwards, and whatever it has thinned isn't put back.
Once the motor has been run, part of that petrol sits in your filter and the lines, not the tank — and your next start sends it straight back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. It is also genuinely risky to drain petrol into a can by the roadside.
How it happens: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. A diesel nozzle mostly won't go into a petrol motor, yet 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 happens. Courtesy car, hire car, or a vehicle that is new. Two vehicles on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. Racing for a train outside Dalmeny and fuelling up en route. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up around Kirkliston
- A green handle for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Many cars state the fuel inside the filler flap or on the cap, so check it on the first fill in any vehicle you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key when a household has one of each. So label it.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car gets its first tank. It seems silly. It works.
- While you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Less petrol makes a weaker blend, so stop as soon as you notice — while remembering that the next stage is unchanged. It is still not to crank it.
Put petrol in a diesel in Kirkliston already?
In that case, there's only a short order of things. Leave it unstarted, with the ignition switched off too. Ask the staff to help you push it clear of the petrol pump if you are still at the forecourt, whether that is BP or anywhere else. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it has run.
If it was AdBlue and not petrol, say so. That is a separate fault — corrosion and deposits and not lost protection — and it has its own page for Kirkliston.
One petrol in a diesel task around Kirkliston costs more than another. Why?
The four situations above are four separate jobs, so no single quote for this would be fair. Which of them you are in is mostly what moves the cost. The proportion matters next, meaning how much of the tank is petrol, followed by the location of your car and whether getting to it is safe for a technician.
Three queries come first, before any quote, rather than after — what went in, how much, has it run — and that is the reason. With those answers, there is a straight figure instead of a range.
About Kirkliston
Kirkliston is a village in the City of Edinburgh, situated near the coast at an elevation of 49 metres, with semi-detached housing being the predominant type of accommodation. Kirkliston lies approximately 8 miles to the west of Edinburgh, close to the nearby settlements of Almondhill and Newbridge. Kirkliston is part of the wider Edinburgh urban area, with the city's amenities and services within easy reach. Kirkliston has a population of around 2910 people, living in a mix of old and new housing stock.
Fuel drain cover across City of Edinburgh, Kirkliston included
Almondhill, Newbridge and Ratho Station are among the spots near Kirkliston that the same teams work, answering petrol in diesel calls across Kirkliston's EH postcode area. We drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in Kirkliston, still?
No position is better: that is where you now are. Keep the car turned off, and ring.