How Worried Should You Be? Petrol in a Diesel Car in Gronant
Not started? Then less anxious than you likely are. "Have I ruined it?" is the first question anyone around Gronant asks, and the honest answer is normally no, because petrol resting in a diesel tank hurts nothing until it is drawn through your fuel system — by ignition priming, by your starter, or by driving. Leave the engine off then call Petrol in Diesel — that is how you keep it that way. Below, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you again.
The engine and petrol in a diesel: what happens
Passing through an engine, diesel is doing two jobs at the same time. It combusts, and before it combusts it lubricates. The high-pressure pump and your injectors are designed to very fine clearances, and the diesel passing through them is what stops those surfaces from wearing down against each other.
The second job petrol does not do at all, and the first it does badly. It is runnier than diesel and takes away the lubrication the system hinges on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
The shape of the issue is clear when you put those together. Contact does not do the damage — movement does. Any tank with petrol in it is a fuel problem. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors downstream.
Gronant, petrol in a diesel: four cases, from mild to significant
The best case there is: filled up, not once started. That petrol is inside your tank and only that tank, and the job is a drain and a flush where your car stands. This is the one situation that can only really take place at a forecourt, because anywhere else the car has been driven to get there.
Ignition on, or started for a second. Once primed, your system has pulled petrol from the tank up to the filter and the fuel lines. Drain, flush, deal with the filter: still normally straightforward.
Your pump now worked a couple of miles on thinned fuel — that's what driving the vehicle does. Tank, lines, filter, then clean fuel put through the entire circuit: that is the work, and the way the car was driven matters as much as the mileage. Short trips, like the school run to the local primary school, are one thing. A run as far as St Asaph, under 10 miles away, is a very different job. So is any mileage on the Moreton Spur, under 15 miles from Gronant, where the engine has been working hard the whole time.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The fuel is not behaving like diesel any more, and your engine is telling you. Pull up wherever you are — the verge on Nant y Gro, a lay-by, a side street — and leave the car there. Lasting damage is very rare if a vehicle is pulled over soon, and the drain and flush that still come first sort it out.
What Gronant drivers get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A fuller tank of the same mix is all it gives, because topping up removes nothing. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice presumes.
Not so: a current diesel copes with a bit of petrol. Rather, the reverse. A current diesel runs its fuel through smaller parts at higher pressure, which makes the protection matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there is no damage done." The driver of a petrol engine fed diesel normally has no choice but to stop, since it will not run, and the harm stops there. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, while your pump wears. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct fault. That petrol is still in your tank after that, and whatever it has thinned is not put back.
The next start draws petrol back round the pump from the lines and your filter, where some of that sits after the engine has run. That is why a DIY tank drain does not leave you sorted — a myth. It's also really hazardous to drain petrol into a can by the kerbside.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and no one means to do it. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol car at all. The forecourt makes it easy, and the error runs one way.
The moment routine stops matching the car is the moment it takes place. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. A rushed fill en route to Prestatyn with a train to catch. A new-to-you diesel Audi A4, its first fuelling, and a driver used to petrol: exactly when it happens. With rain, a call coming in, or a car full of children to deal with, the hand simply does what it always has.
How to prevent petrol in a diesel at your next fill-up around Gronant
- The label is what matters, so read the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Plenty of vehicles state the fuel type inside the filler flap or on the cap, so check there on your first fill in any vehicle you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a home has one of each. So label it.
- Before the nozzle leaves the pump the first time you fill a hired or new car, say "diesel" out loud. Silly, yes, yet it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Add-on devices are available for motors without one, and some diesels are built with a filler that will not accept a petrol nozzle. Useful — but a safety net only, never a reason to stop checking the label.
- Less petrol makes a thinner mix, and so stop as soon as you realise — while remembering that the next stage is unchanged. It is still not to start the vehicle.
Put petrol in a diesel around Gronant already?
In that case, there's just a short order of things. Don't turn your ignition on, and do not crank it. If you are still at the forecourt — Esso or anywhere else — ask the attendants to help you roll the vehicle away from the petrol pump. Then phone 0333 366 0103 and tell us what went in, about how much, and whether it has 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 Gronant page.
One petrol in a diesel task around Gronant costs more than another. Why?
The four situations above are four separate jobs, so no single quote for this would be honest. Which of them you are in is mostly what shifts your cost. Two things come after that: the petrol that went in as a share of what that tank holds, then the spot the vehicle is in and whether our van can reach it safely.
That is why our technicians ask three queries before pricing instead of after: what was put in, how much, and whether it's run. Given those replies, you get a straight figure instead of a range.
About Gronant itself
Gronant is a small coastal village in Flintshire, situated near the towns of Gwespyr and Llanasa, with Woodland Park nearby. Gronant has a population of around 708 people and is characterised by semi-detached housing. Gronant sits at a low elevation of 22 metres above sea level, close to the coast. Gronant is located near the city of St Asaph, which is approximately 6.5 miles away.
Fuel drain cover around Gronant and across Flintshire
Gwespyr, Llanasa and Woodland Park are among the places near Gronant that the same vans work, answering petrol in diesel call-outs across Gronant's LL postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our engineers drain, and your car doesn't need to come to us.
At the pump around Gronant, still?
The best spot there is, then — that is where you are. Phone, and leave it switched off.