Whaley Thorns: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you probably feel. Everyone around Whaley Thorns starts with "have I ruined it?", and the honest answer is normally no: petrol left inside your tank of any diesel remains harmless till priming, cranking or driving pulls it into the system. Keep it that way: leave the engine off and ring Petrol in Diesel. Further down, this page sets out what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
What petrol in a diesel does to the motor
Two jobs fall to diesel on its journey round a motor. Before it burns, it lubricates — and then it burns. Extremely fine tolerances go into the injectors and your high-pressure pump, and just your diesel running through keeps their surfaces from grinding together.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump on that mixture wearing itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the clattering.
The shape of the problem is plain once you put those together. It is movement that does the harm, not contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
How serious is petrol in a diesel? Four situations our technicians see in Whaley Thorns
Filled up, and not started: no case is better. At a forecourt, and really only there, that petrol is still limited to your tank — since everywhere else the vehicle was driven to get to it. The job is emptying and purging on the spot.
Started for a moment, or only your ignition on. Petrol has left the tank and reached your filter and the fuel lines, because the system has been bled. That's generally still an easy task — a drain, a flush, and your filter dealt with.
The pump has worked a few miles on diluted fuel — that's what driving it does. The work is that tank, your lines, your filter and clean fuel through the entire circuit, and how hard the vehicle was driven matters as much as how far. Short trips, such as the school run to Whaley Thorns Primary School, are one thing. Any distance on the M1, under 5 miles from Whaley Thorns, means your engine working hard throughout, and a run to Sheffield, under 25 miles away, makes a very different task as well.
Driven till it protested. Clattering, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer acts like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Church Street. Lasting damage is very rare if a vehicle is stopped soon, and the drain and flush that still come first take care of it.
What Whaley Thorns motorists get told about petrol in a diesel — and the myths in it
Myth: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mixture is all you get, because topping up takes out nothing. Percentage is not how a diesel fuel system copes with petrol, however much that guidance assumes.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that is how a modern diesel moves its fuel, so the protection matters for more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol engine and it usually will not run, and so the motorist stops — and the harm stops with them. Whilst your pump grinds, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Fine and running aren't the same thing.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another issue. The petrol is still inside that tank after that, and what it has thinned is not put back.
The next start draws petrol back round your pump from the fuel lines and your filter, where some of that ends up after the motor has run. That's why a DIY tank drain doesn't sort it — a myth. Draining petrol into a can at the roadside is also truly hazardous.
Petrol in a diesel: how does it occur?
It is rarely carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it easy, and the slip runs one way.
Routine and the car getting out of step is how it happens. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. Filling up in a rush on the way to Langwith - Whaley Thorns, with a train to catch. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. The hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
Avoiding petrol in a diesel next time you fill up in Whaley Thorns
- Green for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- The first fill in a new vehicle is the time to check the filler flap — on it, or on the cap, plenty of vehicles state the fuel they take.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a house with one of each.
- It sounds silly 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.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol in your tank makes a weaker mixture. What to do next does not change, though — still do not start it.
Put petrol in a diesel around Whaley Thorns already?
Short and simple, then, is the order of things. Do not turn the ignition on, and don't crank it. If you are still on the forecourt — JET or anywhere else — ask the attendants to help you push the car clear of the petrol pump. What went in, roughly how much, and if it has run: tell us those when you ring 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a different fault — corrosion and deposits instead of lost lubrication — and it has its own page for Whaley Thorns.
What makes one Whaley Thorns petrol in a diesel job cost more than the next
Four different tasks sit behind the four situations above — which is why there is no fair single quote. Mostly, your cost shifts with which one you're in. Next it is the share — 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 queries come first, before any quote, instead of after — what went in, how much, has it run — and this is the reason. Their answers are what change a range into one firm number.
About Whaley Thorns and its setting
Whaley Thorns is a village in Derbyshire, situated on the riverside at an elevation of 84 metres, with terraced housing being the predominant type of accommodation. Whaley Thorns lies near several other small settlements, including Nether Langwith, Whaley, and Upper Langwith, and is approximately 15 miles from the city of Sheffield. Whaley Thorns has a population of around 1140 residents, who live in a relatively small and close-knit community. Whaley Thorns is also within reasonable distance of major cities, being around 127 miles from London.
Across Derbyshire and in Whaley Thorns: fuel drain cover
Nether Langwith, Whaley and Upper Langwith are among the places near Whaley Thorns that the same teams work, answering petrol in diesel calls across Whaley Thorns's NG postcode area. You need not move your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain.
Still at the pump in Whaley Thorns?
Then you're in the best position there is. Keep it off. Phone.