Should You Worry? Petrol in a Diesel Car in Fangfoss
Probably less than you already are — provided nobody has started the car. Until the ignition primes your pump, your starter cranks, or the car is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the honest reply to the first Fangfoss question — "have I wrecked it?" — normally no. Leave your engine off then phone Petrol in Diesel — that is how you keep it like that. What petrol actually does to a diesel, how to judge how far it's gone, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to the engine?
Passing through a motor, diesel does two jobs at the same time. It protects first, and after that does it burn. Made to extremely fine clearances, the injectors and the pump rely on your diesel moving through them to keep their surfaces from wearing against one another.
The second job petrol does not do at all, and the first it does badly. The rattling comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection your system hinges on, and any pump working on such a blend is wearing itself.
Taken together, they show the shape the trouble has. It's circulation that does the damage, not contact. Any tank with petrol in it is a fuel issue. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
Four situations our engineers see around Fangfoss: how serious is petrol in a diesel?
The best case there can be: filled up, not once started. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol held inside that tank alone, it is drained and cleaned right where it stands, and nothing more is needed.
Started for a second, or just your ignition on. Petrol has come out of that tank and reached your filter and your lines, because the fuel system has been bled. That's generally still an easy task — a drain, a flush, and the fuel filter dealt with.
Those few miles driven meant the pump running on fuel weakened by petrol throughout. Tank, lines, filter, then fresh fuel put through the entire system: that is this work, and the way the car was driven matters as much as the mileage. The school run to St Martin's Church of England Voluntary Aided Primary School, Fangfoss is one thing. Very different a second time: a run to York, under 15 miles away, or some mileage on the M62, under 15 miles from Fangfoss, where the engine never stopped working hard.
Driven until it protested. Rattling, a ragged idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer behaves like diesel. Stop wherever you are — the verge on Station Road, a lay-by, a side street — and leave the vehicle there. What comes first is still the drain and flush, and that takes care of it, with permanent damage very unusual if a car is pulled over quickly.
What Fangfoss people get told about petrol in a diesel — and the stories in it
False: topping up to full with diesel makes it fine. It doesn't. A bigger tank of the same mixture is all you get, since topping up removes nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. Protection counts more on current diesels, not less, since their fuel runs through smaller parts at higher pressure.
"It starts, it drives, and so no harm done" — the myth that catches most drivers than any other. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the harm. A diesel fed petrol normally starts, idles and drives away as though nothing has happened, whilst the pump grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a separate fault. It doesn't put back what petrol has weakened, and the petrol is still inside the tank later on.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol lies in the fuel filter and lines, ready to go right back through your pump on your next start. Also, a can of petrol drained at the kerbside is genuinely risky.
Why petrol in a diesel takes place so easily
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it easy, and the slip runs one way.
Routine and your car falling out of step is when it happens. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A train to catch, and a hurried fill on the way to York. Years of petrol motors behind you, a diesel Renault Clio in front of you on the forecourt for its first tank — that's when. Throw in a back seat full of children, a phone call or rain, and the hand wins.
How to avoid petrol in a diesel at your next fill-up in Fangfoss
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- Check the filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on your first fill in a motor you do not know.
- One of each in the house? Label the key to the diesel — a coloured fob, a sticker — since intending to remember isn't enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds daft and it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for motors without one, and some diesels come with a filler that will not take a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Spotting it halfway? Stop there and then. A weaker blend follows from less petrol inside the tank, yet the next step stays the same: don't start the vehicle.
Fangfoss: already put petrol in a diesel?
In that case, there is just a short order of things. Leave it unstarted, with your ignition switched off as well. Still on the forecourt, at JET or anywhere else? Ask the staff to help you push the car away from the petrol pump. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it's been run.
Corrosion and deposits form the problem with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and read its own Fangfoss page.
Fangfoss petrol in a diesel tasks: why one costs more than another
The four situations above are four different jobs, so no single quote for this would be honest. Mostly, the cost moves with which situation you are in. Where the car is matters too, and whether our van can safely get to it, after the proportion of petrol to what the tank takes.
What went in, how much, and whether it has run — three questions our technicians ask before pricing, not after, for precisely that reason. With those replies, there is a straight figure rather than a range.
About Fangfoss itself
Fangfoss is a small village situated on the riverside in the East Riding of Yorkshire, with a population of around 594 people. Fangfoss has a mix of old and new housing, but detached homes are the predominant type, reflecting the village's relatively affluent character. Fangfoss is located near several other small villages, including Bolton, Gowthorpe, and Youlthorpe, and is about 10 miles from the city of York. Fangfoss sits at an elevation of 24 metres above sea level, in a low-lying area near the River Derwent.
Fuel drain cover across East Riding of Yorkshire, Fangfoss included
Bolton, Gowthorpe and Youlthorpe are among the locations near Fangfoss that the same teams work, answering petrol in diesel call-outs across Fangfoss's YO postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our technicians drain, and your vehicle does not need to come to us.
At the petrol pump in Fangfoss, right now?
Nothing beats it: that's where you now are. Keep it off. Phone.