How Worried Should You Be? Petrol in a Diesel Car in Henllys
Not started? Then less anxious than you probably feel. "Have I wrecked it?" is the first question everyone in Henllys asks, and the honest answer is usually no, because petrol left in a diesel tank hurts nothing till it is dragged through the fuel system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to call, with your engine left off, so it remains that way. The remainder of this page sets out what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its journey round a motor. It lubricates to begin with, and after that does it burn. What stops the surfaces inside your high-pressure pump and your injectors from wearing down against each other is the diesel passing through them — they're designed to very fine gaps.
Of these two jobs, petrol manages the first badly and the second never. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on that mixture wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the clattering.
Together, those make the shape of the problem clear. It is circulation that causes the damage, not contact. Where the petrol is only in the tank, it is a fault of fuel, nothing more. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to the fuel injectors further on.
How serious is petrol in a diesel? Four scenarios our technicians see around Henllys
Fuelled, and not started: no case is better. At a forecourt, and truly only there, that petrol is still confined to the tank — because everywhere else the car was driven to get to it. The job is emptying and flushing on the spot.
A brief spell of running, or merely the ignition on. Petrol has come out of that tank and reached your filter and the fuel lines, since the system has been primed. That is normally still a straightforward job — a drain, a flush, and the filter seen to.
The pump has worked a couple of miles on weakened fuel — that is what driving it meant. Tank, lines, filter, then clean fuel run through the whole system: that is the work, and the way your car was driven matters as much as the mileage. Driving the children to the local primary school is one kind of trip. Any distance on the M4, under 5 miles from Henllys, means your engine has worked hard throughout, and a run to Newport, under 5 miles away, is a very different task too.
Driven on till it protested — rattling, smoke, a lumpy idle, a dead throttle. The motor is telling you the fuel is no longer acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Park Close. A car pulled over soon very seldom has permanent damage, because the fuel drain and the flush, which still go first, take care of it.
Petrol in a diesel stories Henllys motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed when you top up — that tank simply holds more of the same blend. That advice assumes a diesel fuel system handles petrol by percentage. It doesn't.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." More precise components and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. A petrol motor fed diesel normally won't run, so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally starts, ticks over and drives away as if nothing happened — all while its pump wears. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different fault. None of what petrol thinned is put back by it — and later, the tank still contains the petrol.
Myth: "Drain the tank yourself and you're sorted." After your engine has been run, some of the petrol is no longer in the tank: it is in the fuel filter and your lines, and it goes straight back through the pump on the next start. It's also truly risky to drain petrol into a can by the kerbside.
Why petrol in a diesel happens at all
Nobody does it on purpose, and it's rarely carelessness. One way only, since of the nozzles: the slimmer petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol motor. That is how the forecourt makes it easy.
When routine and the car stop matching, it occurs. Hire cars, courtesy cars, and motors that are new to you. One petrol and one diesel on the driveway of the same household. A familiar forecourt with the pumps in a different order. Fuelling up in a hurry on the way to Cwmbran, with a train to catch. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Add a back seat full of kids, a phone call or rain, and the hand takes over.
Henllys people: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is only a clue.
- Check your filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a household with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It seems daft and it works.
- Mistakes like this are simple to make while your mind is on something else, and so the phone goes away.
- Add-on devices are available for cars without one, and some diesels come with a filler that will not take a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside the tank means a weaker mixture. What to do next doesn't change, though — still don't fire it up.
Petrol already in a diesel in Henllys? Start here
The order of things is short, then. Don't turn your ignition on, and do not start it. The attendants on the forecourt — whether at Shell itself or wherever you filled up — will usually help roll it clear of the petrol 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 form the trouble with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Henllys page.
Why one petrol in a diesel task around Henllys costs more than another
The four scenarios above are four different tasks, so no single quote for this would be fair. Chiefly, your cost moves with which one you're in. Where your car is counts too, and whether our van can safely get to it, after the ratio of petrol to what the tank holds.
Three queries come first, before quoting, rather than after — what got in, how much, has it run — and that is the reason. Those replies change a range into a straight figure.
About Henllys itself
Henllys is a suburban area situated on the riverside in Torfaen, Wales, with a mix of detached housing and local amenities. Henllys sits near the city of Newport, approximately 4.5 miles away, and is close to nearby places such as Ty Canol and Coed Eva. Henllys has a population of around 3054 people and is located at an elevation of 163 metres. Henllys is part of the wider Newport urban area, with London around 126 miles to the east.
Henllys and Torfaen: where our fuel drain cover runs
Our vans answering petrol in diesel call-outs in Henllys, in the NP postcode area, also work the spots near it, Ty Canol, Coed Eva and Fairwater among them. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations we drain.
In Henllys and still at the petrol pump?
Then you are in the best position there is. Ring, and keep it switched off.