Should You Worry? Petrol in a Diesel Car in Marley Pots
Provided it hasn't been started, you can worry less than you probably are. Until your ignition primes the pump, the starter turns, or your car is driven, petrol in a diesel tank just rests there and does no harm. Which means the truthful reply to that first Marley Pots question — "have I ruined it?" — usually no. Keep it like that: leave the engine off then phone Petrol in Diesel. The remainder of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to the engine?
On its way through a motor, diesel does two jobs. It lubricates first, and only then does it burn. What stops the surfaces inside the high-pressure fuel pump and your injectors from grinding against one another is your diesel passing through them — they're made to very fine gaps.
Poorly at the first, not at all at the second: that's petrol. A pump running on a petrol mix is wearing itself out, since petrol is runnier than diesel and takes away the lubrication your 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 clattering starts.
Put those together and the shape of the problem is plain. It's circulation that causes the damage, not contact. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, borne by the fuel, into the fuel injectors downstream, which is why a pump that has worked on the petrol is where a mechanical fault starts.
Four situations we see around Marley Pots: how serious is petrol in a diesel?
Filled up, not once started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol held in your tank alone, it is drained and purged on the spot, and nothing more is needed.
Ignition on, or started for a moment. Once primed, your system has pulled petrol from the tank as far as your filter and your lines. That is usually still a straightforward job — a drain, a flush, and your filter seen to.
Those few miles on the road were the pump working on fuel thinned by petrol the whole way. How hard your car was driven matters as much as how far, and this work takes in your tank, your lines, the filter and fresh fuel through the entire system. The school run to English Martyrs' Catholic Primary School, Sunderland is one matter. Any mileage on the A194(M), under 5 miles from Marley Pots, means your engine has worked hard throughout, and a run to Sunderland, under 3 miles away, makes a very different job as well.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. The motor is telling you the fuel is no longer behaving like diesel. Stop on the spot — on the verge on Elmwood Avenue, at the kerb, down a side road — and do not move it again. What comes first is still the drain and flush-through, and that sorts it out, with permanent damage very unusual if a car is pulled over quickly.
Petrol in a diesel stories Marley Pots drivers hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a bigger tank of the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. Lubrication matters more on current diesels, not less, since their fuel passes through smaller parts at higher pressure.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor usually leaves a motor that will not run: the motorist stops, and so does the damage. While your pump wears, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate issue. It doesn't put back what petrol has weakened, and that petrol is still inside your tank later on.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol lies in your filter and lines, waiting to go straight back through the pump at your next start. It is also really risky to drain petrol into a can at the kerbside.
Why petrol in a diesel takes place at all
No one does it on purpose, and it's seldom carelessness. One way only, since of the nozzles: the slimmer petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol motor. That is how the forecourt makes it simple.
Routine and the vehicle getting out of step is how it happens. Hire cars, courtesy cars, and motors that are new to you. Two motors on one driveway, one petrol, one diesel. A familiar forecourt with the pumps in a different order. A rushed fill on the way to Seaburn with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist used to petrol: precisely when it happens. Throw in a back seat full of children, a phone call or rain, and habit takes over.
Preventing petrol in a diesel next time you fill up around Marley Pots
- The label is what counts, and so check the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- Inspect your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in a car you don't know.
- One of each in the home? Mark the key to your diesel — a coloured fob, a sticker — since intending to remember isn't enough.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Put your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- Spotting it halfway? Stop there and then. A thinner mixture results from less petrol inside the tank, but the next step remains the same: don't start it.
Put petrol in a diesel around Marley Pots already?
The order of things is short, then. Starting it is out, and so is switching on your ignition. Yet at the forecourt, at Sainsbury's or anywhere else? Ask the attendants to help you roll the vehicle away from the pump. Phone 0333 366 0103 next, with three answers — the fuel, the approximate quantity, and whether it's run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and see its own Marley Pots page.
What makes one Marley Pots petrol in a diesel job cost more than the next
Four different tasks sit behind the four situations above — which is why there's no fair single quote. The situation itself does most of the work of moving the cost. After that it is the ratio — how much petrol went in against how much the tank takes — and then where the vehicle is and whether a van can reach it safely.
Three questions come first, before any quote, rather than after — what was put in, how much, has it run — and that is the reason. Those replies are what turn a range into one firm number.
About Marley Pots, for a moment
Marley Pots is a suburban area located on the coast of Tyne and Wear, near the city of Sunderland. Marley Pots sits at an elevation of 52 metres, with views out to the North Sea, and is situated close to nearby places such as Witherwack and Carley Hill. Marley Pots is characterised by its predominantly semi-detached housing stock, typical of many suburban areas in the North East of England.
Marley Pots and Tyne and Wear: where our fuel drain cover runs
The teams answering petrol in diesel jobs around Marley Pots, in the SR postcode area, also work the locations around it, Witherwack, Carley Hill and Southwick among them. No need to move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
Marley Pots: still at the petrol pump?
Then you're in the best spot there is. Phone, and leave it turned off.