Goodshaw Chapel: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it hasn't been started. Until the ignition primes the pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank just rests there and does nothing. Which means the truthful reply to that first Goodshaw Chapel query — "have I ruined it?" — usually no. Leave the engine off and call Petrol in Diesel — that is how you keep it that way. Below, this page sets out what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
Diesel has two jobs on its way through a motor. It lubricates to begin with, and after that does it burn. The high-pressure fuel pump and the injectors are made to very fine clearances, and your diesel passing through them is what stops those surfaces from wearing down against each other.
Poorly at the first, not at all at the second: that is petrol. It is runnier than diesel and strips away the protection the system rests on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the knocking comes from.
Seen together, they make clear the shape the problem takes. Contact does not do the damage — circulation does. A tank with petrol in it is a fuel fault. Once your pump has been running on that petrol, a mechanical issue has started: anything shed by a pump that is wearing travels downstream to the injectors with your fuel.
How serious is petrol in a diesel? Four situations our engineers see in Goodshaw Chapel
Fuelled, and not started: nothing beats it. That petrol is inside the tank and only that tank, and the job is a drain and a flush where the car stands. This is the one scenario that can only really occur on a forecourt, as anywhere else the vehicle has been driven to get there.
The ignition turned on, or a brief start. Once primed, the system has drawn petrol out of the tank as far as your filter and the fuel lines. That is usually still a simple task — a drain, a flush, and the fuel filter dealt with.
Driven a few miles. Now the pump has spent these miles labouring on diluted fuel. How hard the car was driven matters as much as how far, and the work takes in your tank, the fuel lines, your filter and clean fuel through the whole system. Driving the kids to Crawshawbooth Primary School is one kind of trip. Any miles on the M65, under 5 miles from Goodshaw Chapel, means the engine working hard throughout, and a run to Preston, under 25 miles away, makes a very different task too.
Rattling, an uneven idle, smoke, a throttle gone soft: driven till it complained. The engine is telling you the fuel is no longer behaving like diesel. Stop where you are — on the verge on Gib Hill Lane, at the kerb, down a side road — and don't move it again. What comes first is still the drain and flush, and that deals with it, with long-term damage very uncommon if a vehicle is stopped early.
Petrol in a diesel myths Goodshaw Chapel drivers hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mix is all it gives, because topping up removes nothing. A diesel fuel system does not tolerate petrol by percentage in the way that guidance presumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. At higher pressure, through finer parts: that's how a current diesel handles its fuel, and so the protection counts for more, not less.
One myth that catches motorists out: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and drives away as if nothing happened — all the while its pump is wearing. Running is not 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 distinct fault. None of what petrol weakened is put back by it — and afterwards, your tank still holds the petrol.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in your filter and lines, ready to go right back through your pump on the next start. It's also genuinely risky to drain petrol into a can by the roadside.
How it happens: petrol in a diesel
Nobody does it on purpose, and it's seldom carelessness. One way only, since 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 car. That's how the forecourt makes it straightforward.
Habit and the vehicle falling out of step is when it occurs. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill on the way to Hapton. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Add a back seat full of kids, a phone call or rain, and habit takes over.
Goodshaw Chapel motorists: how to prevent petrol in a diesel next time
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- Inspect the filler flap. Many vehicles state the fuel 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? Label the key to your diesel — a bright fob, a sticker — because intending to remember is not enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away then keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to refuse a petrol nozzle, and aftermarket devices are available for the rest. Treat it as a safety net, then keep reading the petrol pump.
- Less petrol makes a weaker mixture, so stop as soon as you realise — while remembering that your next stage is unchanged. It is still not to fire it up.
Petrol already in a diesel around Goodshaw Chapel? Begin here
Then the order of things is brief. Do not turn your ignition on, and do not start it. Yet on the forecourt, at Shell or anywhere else? Ask the staff to help you roll the vehicle clear of the petrol pump. What went in, about how much, and whether it's run: tell us those when you ring 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a separate issue — corrosion and deposits and not lost lubrication — and it has its own page for Goodshaw Chapel.
Goodshaw Chapel petrol in a diesel tasks: why one costs more than another
A fair single quote does not exist here: four situations, four separate jobs. What moves the cost is mostly which of them you're in. The share counts next, meaning how much of that tank is petrol, and then the location of your car and whether getting to it is safe for our van.
Before any quote, not after, come three queries: the fuel that went in, the amount, and whether it's run. That's why. A range becomes a straight figure when the answers are in.
About Goodshaw Chapel, briefly
Goodshaw Chapel is a suburban area in Lancashire, situated near the River Irwell and surrounded by the Pennine foothills. Goodshaw Chapel sits at an elevation of 291 metres, with views of the surrounding countryside and nearby villages such as Loveclough and Goodshaw. Goodshaw Chapel is characterized by its predominantly terraced housing stock, reflecting its historical development as a residential community. Goodshaw Chapel is located approximately 17 miles from Preston, making it a commuter base for the city.
Across Lancashire and in Goodshaw Chapel: fuel drain cover
Loveclough, Goodshaw and Goodshaw Fold are among the spots near Goodshaw Chapel that the same teams work, answering petrol in diesel calls across Goodshaw Chapel's BB postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians drain, and your car doesn't need to come to us.
Still at the petrol pump in Goodshaw Chapel?
Then, you could not be in a better position. Keep it off. Phone.