How Worried Should You Be? Petrol in a Diesel Car in Upton End
Likely less than you are now — provided no one has started it. Petrol sitting 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 itself. So the truthful answer to the first query anyone around Upton End asks, "have I ruined it?", is usually no. Petrol in Diesel is who to phone, with your motor left off, and so it remains that way. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening a second time: that's the rest of this page.
Inside the motor: what petrol in a diesel really does
Two tasks fall to diesel on its journey through a motor. It combusts, and before it combusts it lubricates. Very fine clearances are built into the fuel injectors and your high-pressure pump, and just your diesel flowing through stops their surfaces grinding together.
The second job petrol doesn't do at all, and the first it does badly. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the fuel system depends on, and any pump working on that blend is wearing itself.
The shape of the trouble is plain when you put those together. Not contact but circulation is what does the harm. Where that petrol is only in the tank, it is a fault of fuel, nothing more. Whatever a worn pump sheds travels on, borne by the fuel, into the fuel injectors downstream, which is why a pump that has worked on that petrol is where a mechanical problem begins.
Four situations our engineers see around Upton End: how serious is petrol in a diesel?
Fuelled, and never started: no case is better. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept in the tank alone, it is cleared and purged on the spot, and nothing more is needed.
A moment's running, or just the ignition on. With the fuel system primed, the fuel lines and filter now contain petrol that has come from the tank. Still generally straightforward: drain, flush, and the fuel filter seen to.
Your pump now spent a few miles on weakened fuel — that's what driving the vehicle meant. Mileage is only half of it; how hard it was driven counts just as much. Either way this work includes the tank, the lines, your filter and clean fuel through the whole circuit. On the school run to Shillington Lower School, the distance is short. Any mileage on the A1(M), under 10 miles from Upton End, means the engine working hard throughout, and a run to Milton Keynes, under 25 miles away, is a very different job as well.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. What you are hearing is your motor signalling fuel that no longer runs like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Meppershall Road. The fuel drain and flush-through still come first, and they take care of it: when a car is stopped soon, long-term damage is very unusual.
Myths Upton End drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice presumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. Finer components and higher pressure are the way a modern diesel runs its fuel, and that makes the protection count more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. A petrol engine fed diesel usually will not run, and so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a different fault. It does not put back what petrol has weakened, and that petrol is still in the tank afterwards.
Once the motor has run, part of the petrol is in your filter and the fuel lines, not the tank — and your next start sends it straight back through your pump. So the myth "drain your tank yourself and you are sorted" doesn't stand up. Clearing petrol into a can by the roadside is also truly hazardous.
How does petrol in a diesel happen?
Nobody does it on purpose, and it is rarely carelessness. One way only, since of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol vehicle. That's how the forecourt makes it straightforward.
Routine and the car falling out of step is when it happens. Any car that's new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps suddenly in a different order. Rushing for a train outside Arlesey and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it happens. The hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
Next time you fill up in Upton End: avoiding petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the petrol pump's label; the colour is just a hint.
- The first fill in an unfamiliar motor is the time to check the filler flap — on it, or on the cap, plenty of motors state which fuel they take.
- One of each in the home? Mark your key to the diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" aloud. Silly, yes, but it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and aftermarket devices are available for the remainder. Count it as a backstop, then keep checking the pump.
- Stop as soon as you realise. Less petrol inside the tank makes a weaker mixture. It does not change what to do next, which is still not to start it.
Upton End: already put petrol in a diesel?
Then the order of things is short. Leave it unstarted, with the ignition switched off as well. The staff on the forecourt — whether at F C Dawes & Son itself or wherever you filled up — will usually help roll it away from the pump if you ask. What got in, roughly how much, and whether it's run: tell us that when you phone 0333 366 0103.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Upton End page.
What makes one Upton End petrol in a diesel task cost more than the next
The four scenarios above are four separate jobs, so no single quote for this would be fair. What shifts your cost is chiefly which of them you're in. Two things follow that: the petrol that was put in as a share of what that tank holds, then the spot your car is in and whether our van can reach it safely.
That's why our engineers ask three queries before quoting instead of after: what went in, how much, and whether it's run. A range turns into a straight figure when the answers are in.
About Upton End, briefly
Upton End is a small suburban area in Bedfordshire, situated inland at an elevation of 58 metres. Upton End lies approximately 35.5 miles north of London and 17.1 miles southeast of Milton Keynes, near neighbouring areas such as Woodmer End and Bury End. Upton End is characterized by its predominantly semi-detached housing stock, which reflects the typical residential development patterns of the region. Upton End has a population of around 740 residents, making it a relatively small community.
Upton End and Bedfordshire: where our fuel drain cover runs
The teams answering petrol in diesel jobs in Upton End, in the SG postcode area, equally work the places around it, Woodmer End, Bury End and Hillfoot End among them. 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.
In Upton End and still at the petrol pump?
Then, you couldn't be in a better position. Keep the vehicle switched off, and ring.