Eliburn: Petrol in a Diesel Car? How Worried to Be
If it has not been started, you can worry less than you probably are. "Have I ruined it?" is the first question anyone in Eliburn asks, and the truthful answer is generally no, since petrol left in a diesel tank harms nothing until it is drawn through the fuel system — by ignition priming, by your starter, or by being driven. Petrol in Diesel is who to phone, with your motor kept off, and so it remains that way. Keep reading for three things: the effect petrol has inside a diesel engine, the clues of how far it has got, and the way to make sure you don't do it again.
Inside the engine: what petrol in a diesel really does
Diesel has two jobs on its way through a motor. It protects first, and after that does it burn. Extremely fine tolerances are built into the fuel injectors and the high-pressure pump, and just your diesel flowing through stops those surfaces grinding together.
The second job petrol doesn't do at all, and the first it does poorly. A pump working on a petrol mixture is wearing itself out, because petrol is runnier than diesel and takes away the protection your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where any rattling starts.
The shape of the trouble is plain when you put those together. It's movement that does the damage, not contact. Petrol in the tank is a fuel fault. Whatever a worn pump sheds travels on, borne by your fuel, into the fuel injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault starts.
Four scenarios our engineers see around Eliburn: how serious is petrol in a diesel?
Fuelled but never started — as good as it gets. At a forecourt, and genuinely only there, the petrol is still limited to the tank — because anywhere else the vehicle was driven to get to it. The task is draining and rinsing on the spot.
Started for a moment, or only your ignition on. Your system has been bled, so petrol has left the tank and reached the fuel filter and the fuel lines. Drain, flush, deal with the fuel filter: still usually easy.
A few miles driven, and the pump has spent each of them running on diluted fuel. Tank, lines, filter, then clean fuel put through the entire system: that's this work, and the way your car was driven matters as much as the distance. On the school run to the local primary school, the distance is small. Very different a second time: a trip to Dunfermline, under 15 miles away, or some mileage on the M8, under 3 miles from Eliburn, where the motor kept working hard.
Driven until it complained. Clattering, a ragged idle, smoke, a throttle that has gone soft. The engine is telling you your fuel is no longer behaving like diesel. Whether it is the verge on Houstoun Road, a lay-by or a side street, stop where you are then leave it. What goes first is still the drain and flush, and that sorts it out, with permanent damage very uncommon if a vehicle is pulled over early.
What Eliburn 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 will be fine" — a myth. It won't. A bigger tank of the same mixture is all you get, because topping up takes out nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Smaller parts and higher pressure are how a current diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most people than any other. A petrol engine fed diesel normally will not run, and so the motorist stops and the harm stops with them. Whilst the pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Being able to run is not the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. None of what petrol diluted gets put back by it — and later, the tank still contains that petrol.
If the motor has run, part of that petrol is in the fuel filter and your lines, not the tank — and the next start pulls it right back through the pump. So the myth "drain that tank yourself and you are sorted" does not stand up. And, a can of petrol drained by the roadside is truly dangerous.
How it happens: petrol in a diesel
Nobody does it on purpose, and it's seldom carelessness. A diesel nozzle generally will not fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and just in one direction.
Habit and the car falling out of step is how it happens. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A forecourt you know, but with its pumps arranged differently. Fuelling up in a hurry on the way to Livingston North, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Tiguan in front of you at the forecourt for its first tank — that is when. Add a back seat full of children, a phone call or rain, and the hand takes over.
Preventing petrol in a diesel next time you fill up around Eliburn
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Read the petrol pump's label; the colour is just a clue.
- Check your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you do not know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a house has one of each. So label it.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It sounds silly and it does the trick.
- Put your phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for vehicles without one. They are a safety net, not a reason to stop reading the pump.
- Stop as soon as you notice. Less petrol inside that tank means a thinner mix. It doesn't change what to do next, which is still not to start the car.
Petrol already in a diesel in Eliburn? Begin here
Then the order of things is brief. Do not fire it up, and do not switch the ignition on. The attendants on the forecourt — whether at BP itself or wherever you filled up — will usually help roll it clear of the petrol pump if you ask. What went in, about how much, and if it's run: tell us that when you call 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a separate fault, with its own page for Eliburn, since AdBlue brings corrosion and deposits instead of lost protection.
What makes one Eliburn petrol in a diesel job cost more than the next
There is no fair single quote for this, since the four situations above are four separate tasks. The scenario itself does most of the work of moving your cost. Where the car is counts too, and whether our van can safely get to it, after the proportion of petrol to what the tank takes.
What was put in, how much, and whether it's run — three queries our engineers ask before pricing, not after, for precisely that reason. Those replies change a range into a straight figure.
About Eliburn itself
Eliburn is a suburban area situated on the shores of a lake in West Lothian, with a mix of detached housing and local amenities. Eliburn sits at an elevation of 139 metres, overlooking the surrounding countryside. Eliburn is located near several other suburban areas, including Deans, Knightsridge, and Kirkton, and is within commuting distance of Dunfermline. Eliburn has a population of approximately 3903 residents.
Fuel drain cover across West Lothian, Eliburn included
Our teams answering petrol in diesel jobs in Eliburn, in the EH postcode area, equally work the locations around it, Deans, Knightsridge and Kirkton among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we work, and the car doesn't need to come to us.
In Eliburn and still at the pump?
The best place there is, then — that's where you are. Switched off it stays; then call.