Petrol in a Diesel Car in Wern: How Worried Should You Be?
Far less than you likely are, if it hasn't been started. Everyone around Wern begins with "have I wrecked it?", and the honest answer is normally no: petrol left in your tank of any diesel stays harmless until priming, cranking or driving pulls it into the system. Petrol in Diesel is who to call, with your engine left off, and so it stays that way. Further down, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
Inside the engine: what petrol in a diesel does
Two jobs fall to diesel on its route round a motor. Before it burns, it protects — then it burns. What stops the surfaces inside the high-pressure fuel pump and the injectors from grinding against one another is the diesel passing through them — they're built to very fine gaps.
The second task petrol does not do at all, and the first it does poorly. A pump working on a petrol mixture is wearing itself out, since petrol is runnier than diesel and strips out the protection the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that's where the knocking comes.
Put these together and the shape of the trouble is clear. It's movement that causes the harm, not contact. Where the petrol is only in your tank, it is an issue of fuel, nothing more. Whatever a worn pump sheds goes on, borne by your fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault begins.
How bad is petrol in a diesel? Four scenarios our engineers see in Wern
Filled up, and not started: nothing beats it. Only your tank has petrol in it, so the task is emptying your tank and flushing the system where the vehicle stands. This scenario can only really occur at a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or just the ignition on. Petrol has left the tank and reached your filter and the fuel lines, because the system has been bled. That's generally still a straightforward task — a drain, a flush, and the fuel filter dealt with.
The pump now worked a couple of miles on thinned fuel — that's what driving the car meant. How hard your car was driven counts as much as how far, and the work covers the tank, the lines, the filter and clean fuel through the whole circuit. The school run to Weston Rhyn Primary School is one thing. Getting as far as Wrexham, under 15 miles away, makes a very different job — as does any miles on the M53, under 25 miles from Wern, with your engine labouring hard all the way.
Driven on until it protested — knocking, smoke, an uneven idle, a soft throttle. That's the engine telling you its fuel no longer is behaving like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Station Road. What comes first is still the fuel drain and flush-through, and that takes care of it, with lasting damage very uncommon if a vehicle is stopped early.
Stories Wern motorists hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. Nothing comes out when you top up — the tank simply holds more of the same blend. That guidance presumes a diesel fuel system handles petrol by percentage. It does not.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through finer components: that's how a current diesel moves its fuel, and so the lubrication matters for more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more drivers than any other. Feed diesel to a petrol engine and it normally won't run, so the motorist stops — and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, while the pump grinds. Being able to run is not proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, supposed for another problem. It doesn't put back what petrol has thinned, and the petrol is still inside the tank later.
Myth: "Drain the tank yourself and you are sorted." After the engine has run, some of that petrol is no longer inside that tank: it's in the filter and the lines, and it goes right back through your pump on the next start. And, a can of petrol filled by the roadside is genuinely hazardous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol motor at all. So the error runs one way.
The moment habit stops matching the vehicle is the moment it happens. Any car that's new to you — a hire car, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. Your usual forecourt, its pumps suddenly in a different order. Rushing for a train outside Chirk and fuelling up en route. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Add a back seat full of children, a phone call or rain, and the hand takes over.
Next time you fill up in Wern: avoiding petrol in a diesel
- The label is what counts, and so check the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- Many vehicles state the fuel inside your filler flap or on the cap, and so check it on your first fill in any vehicle you don't know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, in a home with one of each.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for the remainder. Treat it as a backstop, then keep reading the petrol pump.
- Stop the moment you realise. Less petrol inside that tank means a weaker mix. It doesn't change what to do next, which is still not to crank it.
Put petrol in a diesel around Wern already?
The order of things is short, then. Do not crank it, and don't turn the ignition on. Yet at the forecourt, at Shell or anywhere else? Ask the attendants to help you roll the vehicle clear of the petrol pump. Phone 0333 366 0103 next, with three answers — the fuel, the rough quantity, and whether it's run.
If it was AdBlue instead of petrol, say so. That is a separate fault — corrosion and deposits and not lost lubrication — and it has its own page for Wern.
What makes one Wern petrol in a diesel job cost more than the next
The four situations above are four separate tasks, so no single price for this would be fair. Chiefly, the cost moves with which situation you are in. Where the car is counts too, and whether our van can safely get to it, after the share of petrol to what your tank takes.
What got in, how much, and if it has run — three queries we ask before quoting, not after, for precisely that reason. A range becomes a straight figure when those answers are in.
About Wern, briefly
Wern is a small village in Shropshire, situated on the riverside in the West Midlands region of England. Wern has a population of around 518 people and is characterized by predominantly detached housing. Wern is located near the villages of Weston Rhyn, Upper Hengoed, and Rhos, and is approximately 10 miles from the city of Wrexham. Wern sits at an elevation of 141 metres, with the nearest major city being Wrexham and London being around 158 miles away.
Across Shropshire and in Wern: fuel drain cover
Petrol in diesel calls around Wern — part of the SY postcode area — go to vans that also cover the locations around it, Weston Rhyn, Upper Hengoed and Rhos included. The car doesn't need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Wern and still at the petrol pump?
The best place there is, then — that's where you are. Keep it off. Ring.