Pewterspear: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, if it hasn't been started. Everyone in Pewterspear begins with "have I wrecked it?", and the fair answer is usually no: petrol left inside your tank of a diesel stays harmless until priming, cranking or driving pulls it into the system. To keep the car like that, phone Petrol in Diesel and leave the engine alone. The rest of this page explains what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you a second time.
Petrol in a diesel: what does it do to the motor?
Diesel has two jobs on its way through a motor. Before it ignites, it protects — then it combusts. Your high-pressure pump and the fuel injectors are built to very fine tolerances, and the diesel passing through them is what stops those surfaces from wearing against each other.
The second task petrol does not do at all, and the first it does poorly. A pump running on a petrol mixture is wearing itself out, since petrol is thinner than diesel and strips out the protection your fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where any clattering comes.
Put these together and the shape of the trouble is plain. Not contact but movement is what does the harm. Petrol in the tank is a fuel fault. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors downstream.
Pewterspear, petrol in a diesel: four cases, from mild to significant
The best case there can be: filled up, not once started. That petrol is inside the tank and just the tank, and the job is a drain and a flush where your car sits. This is the one scenario that can only truly take place at a forecourt, as anywhere else the car has been driven to get there.
Ignition on, or started for a second. The fuel system has been primed, and so petrol has left your tank and reached the filter and the lines. Normally nothing more than emptying, purging and seeing to the filter, and so still simple.
Those few miles driven were the pump working on fuel diluted by petrol the whole way. Tank, lines, filter, then clean fuel put through the entire system: that's this work, and the way your car was driven counts as much as the miles. On the school run to Stretton St Matthew's CofE Primary School, the mileage is short. Any miles on the M56, under a mile from Pewterspear, means the engine working hard throughout, and a run to Salford, under 15 miles away, is a very different task as well.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer runs like diesel. Pull up wherever you are — the verge on Woodbridge Close, a lay-by, a side street — and leave it there. What comes first is still the drain and flush-through, and that sorts it out, with lasting damage very unusual when a vehicle is stopped early.
What Pewterspear drivers get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed when you top up — your tank simply carries more of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance supposes.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through finer parts: that's how a current diesel handles its fuel, so the lubrication matters for more, not less.
"It starts, it drives, so there is no harm" — the myth that trips up more drivers than any other. The driver of a petrol engine fed diesel normally stops, since it will not run, and the harm stops there. Feed petrol to a diesel and it generally starts, ticks over and drives away as if nothing has happened — all while its pump is wearing. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a distinct issue. None of what petrol weakened gets put back by it — and later, the tank still holds that petrol.
Once the engine has been run, part of that petrol is in the fuel filter and your lines, not that tank — and your next start pulls it straight back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't stand up. It's also genuinely dangerous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
It takes place when routine and the car stop matching. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. Your normal forecourt, its pumps suddenly in a different order. A rushed fill en route to Warrington Bank Quay with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it happens. Throw in rain, a phone call or a back seat full of children, and your hand does what it has always done.
How to avoid petrol in a diesel on your next fill-up around Pewterspear
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what matters.
- In a car you don't know, look inside the flap over your filler or at the cap before the first fill: many motors state the fuel type there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in 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 sounds daft. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol inside your tank makes a thinner mixture. It does not change what to do next, which is still not to start it.
Pewterspear: already put petrol in a diesel?
Then the order of things is brief. Starting it is out, and so is switching on your ignition. The staff on the forecourt — whether at Morrisons itself or wherever you filled up — will usually help push it clear of the pump if you ask. Then call 0333 366 0103 and tell us what went in, roughly how much, and whether it has run.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Pewterspear, since AdBlue brings corrosion and deposits instead of lost lubrication.
One petrol in a diesel task in Pewterspear costs more than another. Why?
The four situations above are four separate jobs, so no single quote for this would be honest. What shifts your cost is mostly which of them you're in. After that it's the share — how much petrol got in against how much that tank takes — and then where your car is and whether a van can reach it safely.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and this is the reason. With those answers, you get a straight figure instead of a range.
About Pewterspear, briefly
Pewterspear is a locality in Cheshire, situated on the riverside at an elevation of 73 metres, with detached housing being the predominant type of accommodation. Pewterspear lies near several other small places, including Appleton Park, Dudlows Green, and Stretton, and is approximately 14 miles from the city of Salford. Pewterspear is also relatively far from London, at a distance of around 163 miles. Pewterspear has a small population of around 970 residents.
Pewterspear and Cheshire: where our fuel drain cover runs
Pewterspear rests in the WA postcode area, and our teams that answer petrol in diesel calls there work the locations around it as well — Appleton Park, Dudlows Green and Stretton among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our technicians work, and the vehicle doesn't need to move to us.
Pewterspear: still at the pump?
Then, you could not be in a better spot. Phone, and leave it turned off.