Petrol in a Diesel Car in Downend: How Worried Should You Be?
Provided it has not been started, you can worry far less than you likely are. Everyone in Downend starts with "have I wrecked it?", and the fair answer is generally no: petrol resting inside your tank of any diesel stays harmless till priming, cranking or driving pulls it into your fuel system. Leave the motor off then ring Petrol in Diesel — that keeps it like that. What petrol actually does to a diesel, how to judge how far it's travelled, and how to stop it from happening a second time: that is the remainder of this page.
Your engine and petrol in a diesel: what goes on
Two tasks fall to diesel on its journey through a motor. Oiling comes before burning; it does both. Built to extremely fine clearances, the fuel injectors and your pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
The second task petrol does not do at all, and the first it does badly. The clattering comes from petrol being made not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the fuel system depends on, and any pump running on such a blend is wearing itself.
The shape of the issue is plain when you put those together. Not contact but movement is what does the harm. Where the petrol is only inside your tank, it's a problem of fuel, nothing more. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has worked on the petrol is where a mechanical problem begins.
Four scenarios we see in Downend: how serious is petrol in a diesel?
Filled up, and never started: nothing beats it. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol kept inside the tank alone, it is emptied and purged right where it stands, and nothing more is needed.
Ignition on, or started for a second. Petrol has come out of your tank and got to the fuel filter and the fuel lines, since your system has been primed. Usually nothing more than draining, cleaning and sorting your filter, and so still simple.
Those few miles on the road were your pump running on fuel diluted by petrol throughout. Tank, lines, filter, then clean fuel run through the whole system: that's this work, and the way the vehicle was driven matters as much as the distance. Driving the children to Wicor Primary School is one sort of trip. A run as far as Portsmouth, under 5 miles away, is a very different task. So is any mileage on the M27, under a mile from Downend, where the motor has been working hard throughout.
Driven on until it complained — rattling, smoke, a ragged idle, a soft throttle. That is your motor telling you its fuel has stopped behaving like diesel. Stop on the spot — on the verge on Down End Road, at the kerb, down a side road — and do not move it. A car stopped quickly very seldom has permanent damage, because the drain and the flush, which still go first, take care of it.
Petrol in a diesel stories Downend people hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up takes out nothing; it gives you a fuller tank of the same mixture. That guidance supposes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through more precise parts: that's how a newer diesel moves its fuel, and so the protection matters more, not less.
"It starts, it drives, so there is no harm" — the myth that catches more drivers than any other. Diesel in a petrol motor usually leaves a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it usually fires up, idles and drives away as if nothing happened — all while its pump wears. Being able to run is not the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a different problem. The petrol is still inside the tank afterwards, and whatever it has thinned isn't put back.
The next start draws petrol back round the pump from the lines and the filter, where some of that ends up after your engine has run. That's why draining your tank yourself doesn't sort it — a myth. It's also genuinely dangerous to drain petrol into a can at the roadside.
Why petrol in a diesel takes place at all
Nobody does it on purpose, and it's seldom carelessness. A diesel nozzle generally will not fit a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake easy, and only in that direction.
It takes place when habit and your car stop matching. Hire cars, courtesy cars, and motors that are new to you. Two vehicles on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Filling up in a rush on the way to Portchester, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it happens. The hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Next time you fill up around Downend: avoiding petrol in a diesel
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- Plenty of vehicles state the fuel inside your filler flap or on the cap, so check it on your first fill in a vehicle you don't know.
- One of each in the home? Label the key to your diesel — a coloured fob, a sticker — since meaning to remember is not enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" aloud. Silly, yes, but it works.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices are available for the rest. Treat it as a backstop, and keep checking the petrol pump.
- Less petrol makes a weaker mixture, and so stop the moment you notice — though remembering that your next step is unchanged. It is still not to start the car.
Already put petrol in a diesel in Downend?
Then the order of things is short. Starting it is out, and so is turning on the ignition. Ask the attendants to help you roll it away from the petrol pump if you are still at the forecourt, whether that is BP or somewhere else. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it has run.
Say so if it was AdBlue instead of petrol: it's a separate fault, with its own page for Downend, because AdBlue brings corrosion and deposits instead of lost lubrication.
Why one petrol in a diesel job around Downend costs more than another
The four scenarios above are four separate tasks, so no single price for this would be fair. What shifts the cost is mostly which of them you're in. Where your car is counts too, and whether a technician can safely get to it, after the share of petrol to what the tank holds.
Three questions come first, before any quote, rather than after — what went in, how much, has it run — and that is the reason. Those replies are what change a range into one firm number.
About Downend and its setting
Downend is a coastal suburban area in Hampshire, situated near the major city of Portsmouth. Downend sits at a low elevation of around 13 metres, close to the Solent Strait and the Isle of Wight. Downend is characterized by its predominantly detached housing stock, reflecting its development as a residential area. Downend is located near other suburban areas, including Wallington and Fareham.
Fuel drain cover across Hampshire, Downend included
Our teams answering petrol in diesel calls around Downend, in the PO postcode area, equally work the spots around it, Wallington, Fareham and North Fareham among them. Our engineers drain wherever the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Downend: still at the petrol pump?
The best position there is, then — that's where you are. Leave the vehicle switched off, then ring.