Coneygar: Petrol in a Diesel Car? How Worried to Be
Likely less than you are now — as long as no one has started it. Petrol sitting in a diesel tank does nothing to the motor till something draws it through your fuel system — your ignition priming your pump, your starter, or the drive on its own. So the truthful answer to the first query everyone in Coneygar asks, "have I ruined it?", is generally no. Petrol in Diesel is who to call, with your engine kept off, so it remains that way. 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 doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
Diesel has two jobs on its way through an engine. It ignites, and before it burns it protects. What keeps the surfaces inside the high-pressure fuel pump and your injectors from wearing down against one another is the diesel flowing through them — they are built to extremely fine tolerances.
The second job petrol does not 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 reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system depends on, and any pump working on such a blend is wearing itself.
Together, those make the shape of the problem plain. The damage is done by circulation, not by contact. Any tank with petrol in it is a fuel problem. The beginning of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors beyond it.
Petrol in a diesel around Coneygar: how bad is it? Four situations
Filled up, and never started: nothing beats it. Only your tank has petrol in it, so the task is draining that tank and rinsing the fuel system where the car stands. This situation can only really take place on a forecourt: anywhere else, the vehicle got there by being driven.
Your ignition turned on, or a short start. Petrol has left the tank and got to the fuel filter and the fuel lines, since the fuel system has been primed. Still usually easy: drain, flush, and the filter seen to.
Driven a few miles. Now your pump has spent these miles running on thinned fuel. Tank, lines, filter, then fresh fuel run through the entire system: that is this work, and the way the vehicle was driven counts as much as the miles. Short trips, like the school run to St Catherine's Roman Catholic School, are one thing. Very different a second time: a trip to Wells, under 50 miles away, or some distance on the M5, under 25 miles from Coneygar, where the motor never stopped running hard.
Driven on till it complained — clattering, smoke, a ragged idle, a dead throttle. The fuel is not acting like diesel any more, and your motor is saying so. Stop on the spot — on the verge on Coneygar Road, at the kerb, down a side road — and don't move it again. What goes first is still the drain and flush, and that takes care of it, with permanent damage very uncommon if a car is stopped quickly.
Petrol in a diesel stories Coneygar motorists hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up removes nothing; it gives you a fuller tank of the same mix. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: a newer diesel copes with a bit of petrol. Rather, the opposite. More precise components and higher pressure are the way a newer diesel runs its fuel, and that makes the protection count more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most people than any other. Diesel in a petrol motor generally means a motor that will not run: the motorist stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump wears. Running isn't the same as fine.
An old workaround for a different problem lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." It does not put back what petrol has weakened, and that petrol is still in your tank later.
Once your engine has been run, part of the petrol is in the fuel filter and the fuel lines, not the tank — and the next start pulls it straight back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. It's also genuinely dangerous to drain petrol into a can by the roadside.
Why petrol in a diesel takes place so easily
On purpose? Never. Through carelessness? Rarely, if ever. A diesel nozzle mostly will not fit a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in one direction.
Routine and your car falling out of step is how it takes place. A new car, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. A well-known forecourt with the pumps in a different order. A train to catch, and a hurried fill on the way to Maiden Newton. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. Add rain, a phone call or a back seat full of kids, and the hand does what it has always done.
Next time you fill up in Coneygar: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Check your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in any vehicle you do not know.
- One of each in the house? Label your key to the diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- 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 pump. It seems daft and it does the trick.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for the remainder. Treat it as a safety net, and keep checking the pump.
- Stop the moment you realise. Less petrol inside the tank makes a weaker blend. It doesn't change what to do next, which is still not to start it.
Petrol already in a diesel in Coneygar? Start here
Then the order of things is short. Starting it is out, and so is switching on your ignition. Ask the staff to help you push it away from the petrol pump if you are still at the forecourt, whether that's Esso or somewhere else. Next, 0333 366 0103. We'll ask what went in, about how much, and if it has been run.
If it was AdBlue instead of petrol, say so. That's a different fault — corrosion and deposits instead of lost lubrication — and it has its own page for Coneygar.
Coneygar petrol in a diesel tasks: why one costs more than another
The four scenarios above are four separate jobs, so no single quote for this would be fair. Mostly, your cost shifts with which one you are in. The proportion matters next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for a technician.
Ahead of any quote, not after, come three queries: the fuel that got in, the quantity, and whether it's run. That is why. A range turns into a straight figure when the replies are in.
About Coneygar
Coneygar is a coastal suburban area in Dorset, situated near the towns of Bridport and Allington, with St Andrews Well nearby. Coneygar has a relatively low elevation of 31 metres and is located approximately 125.6 miles from London. Coneygar is characterised by its predominant flat housing and a population of around 2797 residents. Coneygar sits within the South West region of England, close to the nearest city of Wells, which is 32.8 miles away.
Fuel drain cover across Dorset, Coneygar included
St Andrews Well, Bridport and Allington are among the spots near Coneygar that the same teams work, answering petrol in diesel jobs across Coneygar's DT postcode area. The car doesn't need to move to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Coneygar: still at the pump?
Then, you could not be in a better place. Keep the car turned off, then ring.