Should You Worry? Petrol in a Diesel Car in Saunderton
Not started? Then less anxious than you probably feel. Everyone in Saunderton begins with "have I ruined it?", and the honest answer is usually no: petrol resting in your tank of a diesel remains harmless until priming, cranking or driving pulls it into the system. Keep it that way: leave your engine off and call Petrol in Diesel. The rest 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 again.
Petrol in a diesel: what does it do to the engine?
On its way through a motor, diesel does two jobs. It combusts, and before it combusts it lubricates. What stops the surfaces inside the high-pressure pump and your injectors from wearing down against each other is your diesel passing through them — they're made to very fine gaps.
Of these two tasks, petrol manages the first poorly and the second never. The rattling comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication your system depends on, and any pump running on such a mix is wearing itself.
Seen together, they show the shape the problem has. Not contact but movement is what causes the harm. A tank with petrol in it is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Four scenarios our technicians see around Saunderton: how bad is petrol in a diesel?
Fuelled up, never started. The best case there can be. At a forecourt, and genuinely only there, the petrol is still confined to the tank — because anywhere else your car was driven to reach it. The task is emptying and cleaning on the spot.
Started for a second, or just the ignition on. Once primed, the fuel system has drawn petrol out of your tank up to the filter and your lines. That is generally still a straightforward job — a drain, a flush, and the fuel filter seen to.
Driven a few miles. Now the pump has spent these miles labouring on weakened fuel. Tank, lines, filter, then fresh fuel run through the entire system: that's the work, and the way your car was driven counts as much as the miles. A school run to Bledlow Ridge School is one matter. Any distance on the M40, under 5 miles from Saunderton, means your engine has worked hard throughout, and a run to Oxford, under 25 miles away, is a very different job as well.
Driven till it protested. Knocking, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is your motor reporting fuel that no longer acts like diesel. Pull up wherever you are — the verge on Deanfield Close, a lay-by, a side street — and leave it where it is. The drain and flush-through still come first, and they take care of it: if a vehicle is pulled over early, long-term damage is very rare.
What Saunderton drivers get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing comes out when you top up — that tank just holds more of the same mixture. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. More precise parts and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
The myth that catches drivers off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally means a motor that won't run: the motorist stops, and so does the harm. Feed petrol to a diesel and it normally fires up, idles and pulls away as if nothing has happened — all while its pump wears. Fine and running aren't the same thing.
An outdated fix for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol thinned is put back by it — and later, the tank still holds the petrol.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol lies in the fuel filter and lines, ready to go straight back through your pump at the next start. And, a can of petrol filled at the kerbside is truly dangerous.
How it happens: petrol in a diesel
No one does it on purpose, and it's rarely carelessness. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol car at all. The forecourt makes it easy, and the mistake runs one way.
It happens when habit and your car stop matching. Any vehicle that is new to you — hired, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. A familiar forecourt with the pumps in a different order. A rushed fill on the way to the nearest station with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: precisely when it takes place. Add rain, a phone call or a back seat full of kids, and the hand does what it has always done.
Saunderton drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Read the pump's label; the colour is just a clue.
- The first fill in a new vehicle is the time to check the filler flap — inside it, or on the cap, many vehicles state the fuel to use.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a home with one of each.
- "Diesel", aloud, before you lift the nozzle — every time a new or hired car needs its first tank. It seems silly. It works.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop checking the petrol pump.
- Spotting it halfway? Stop there and then. A thinner mix results from less petrol in that tank, but your next step remains the same: don't start the car.
Saunderton: already put petrol in a diesel?
Then, there is only a short order of things. 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 Esso or anywhere else. Ring 0333 366 0103 next, with three facts — your fuel, the rough volume, and whether it has run.
Corrosion and deposits are the problem with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Saunderton page.
Saunderton petrol in a diesel tasks: why one costs more than another
Four separate tasks lie behind the four scenarios above — which is why there is no honest single price. The situation itself does most of the work of moving your cost. Where your car is matters too, and whether a van can safely reach it, after the share of petrol to what that tank holds.
That is why our engineers ask three questions before pricing rather than after: what was put in, how much, and if it has run. Those answers change a range into a straight figure.
About Saunderton
Saunderton is a small village in Buckinghamshire, situated in the inland countryside of the Chiltern Hills at an elevation of around 117 metres. Saunderton lies near the villages of Bradenham and Bledlow Ridge, and is within commuting distance of Oxford, which is approximately 19 miles away. Saunderton has a population of around 711 people, predominantly living in semi-detached housing.
Fuel drain cover in Saunderton and across Buckinghamshire
Saunderton rests in the HP postcode area, and the vans that answer petrol in diesel call-outs there work the locations around it as well — Bradenham, Crownfield and Bledlow Ridge among them. The vehicle doesn't need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Saunderton and still at the pump?
Then, you couldn't be in a better place. Keep the car switched off, and ring.