Petrol in a Diesel Car in Newmarket: How Worried Should You Be?
Far less than you probably are, if it has not been started. Everyone around Newmarket starts with "have I ruined it?", and the fair answer is normally no: petrol resting in the tank of any diesel remains harmless until priming, cranking or driving draws it into the fuel system. Petrol in Diesel is who to call, with your engine left off, and so it stays that way. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the engine?
On its way through an engine, diesel does two tasks. Before it ignites, it lubricates — and then it burns. Very fine clearances go into the injectors and the high-pressure fuel pump, and just your diesel flowing through stops those surfaces grinding together.
The second job petrol does not do at all, and the first it does badly. The clattering 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 the system rests on, and any pump running on that mixture is wearing itself.
The shape of the problem is plain once you put those together. It's movement that does the damage, not contact. Where that petrol is only inside the tank, it's a fault of fuel, nothing more. The start of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Newmarket, petrol in a diesel: four cases, from mild to serious
Fuelled up, never started. The best case there can be. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol kept in the tank alone, it is cleared and flushed right where it stands, and nothing more is needed.
Your ignition turned on, or a short start. With the fuel system primed, the fuel lines and filter already hold petrol that came from that tank. Still usually easy: drain, flush, and the fuel filter sorted.
Those few miles on the road meant the pump working on fuel thinned by petrol throughout. The work is your tank, the lines, the fuel filter and fresh fuel through the entire circuit, and how hard your car was driven counts as much as how far. Short trips, like the school run to Holmgate Primary School and Nursery, are one thing. A run as far as Sheffield, under 25 miles away, is a very different job. So is any mileage on the M1, under 5 miles from Newmarket, where the motor has been working hard throughout.
Driven on till it protested — clattering, smoke, a lumpy idle, a soft throttle. What you are hearing is your engine reporting fuel that no longer behaves like diesel. Pull up wherever you are — the verge on Newmarket Lane, a lay-by, a side street — then leave the car there. Permanent damage is very unusual when a vehicle is stopped soon, and the drain and flush that still go first take care of it.
What Newmarket motorists get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mix is all it gives, because topping up takes out nothing. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. At higher pressure, through smaller components: that's how a current diesel moves its fuel, and so the lubrication matters for more, not less.
"It starts, it drives, so there is no harm" — the myth that catches more people than any other. Feed diesel to a petrol engine and it generally will not run, and so the motorist stops — and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Being able to run is not the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate fault. It does not put back what petrol has weakened, and the petrol is still inside your tank later.
Myth: "Drain your tank yourself and you're sorted." Once the engine has run, some of that petrol is no longer in your tank: it's in your filter and the lines, and it goes straight back through the pump on the next start. It's also genuinely risky to drain petrol into a can by the kerbside.
Why petrol in a diesel takes place at all
No one does it on purpose, and it is rarely carelessness. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol motor. That's how the forecourt makes it simple.
The moment habit stops matching your car is the moment it happens. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. Fuelling up in a hurry on the way to Alfreton, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it occurs. The hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Next time you fill up around Newmarket: avoiding petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Check the pump's label; the colour is just a hint.
- Plenty of cars state the fuel inside your filler flap or on the cap, so check it on your first fill in any motor you do not know.
- One of each in the household? Label the key to your diesel — a coloured fob, a sticker — because intending to remember is not enough.
- It seems daft and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, then keep reading the pump.
- Less petrol means a thinner blend, so stop the moment you notice — while remembering that the next step is unchanged. It's still not to crank it.
Newmarket: already put petrol in a diesel?
Then the order of things is brief. Do not switch your ignition on, and don't fire it up. The attendants on the forecourt — whether at Tesco itself or wherever you filled up — will normally help push it clear of the pump if you ask. Then phone 0333 366 0103 and tell us what went in, about how much, and if it has run.
Say so if it was AdBlue rather than petrol: it is a different issue, with its own page for Newmarket, since AdBlue brings corrosion and deposits instead of lost protection.
Newmarket petrol in a diesel tasks: why one costs more than another
The four situations above are four separate jobs, so no single price for this would be fair. What shifts the cost is chiefly which of them you are in. Where your car is counts too, and whether a van can safely get to it, after the ratio of petrol to what that tank holds.
Ahead of any quote, not after, we ask three questions: the fuel that was put in, the volume, and whether it has run. That is why. A range turns into a straight figure once the answers are in.
About Newmarket and its setting
Newmarket is a suburban area in Derbyshire, situated on the riverside at an elevation of around 135 metres. Newmarket lies approximately 15 miles from Sheffield and is close to nearby places such as Bacons Spring and Clay Cross. Newmarket has a population of around 901 people and predominantly consists of semi-detached housing. Newmarket is also relatively distant from London, being around 126.8 miles away.
Fuel drain cover across Derbyshire, Newmarket included
The vans answering petrol in diesel jobs in Newmarket, in the S postcode area, equally work the places around it, Bacons Spring, Clay Cross and Henmoor among them. You need not bring the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
At the pump in Newmarket, still?
No position is better: that is where you now are. Keep it off. Ring.