How Worried Should You Be? Petrol in a Diesel Car in Fishpool
Less than you probably are, if it has not been started. Everyone around Fishpool starts with "have I wrecked it?", and the honest answer is usually no: petrol left inside the 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 motor switched off. 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 a second time.
Petrol in a diesel: what does it do to the engine?
Two tasks fall to diesel on its journey round a motor. It combusts, and before it burns it protects. What keeps the surfaces inside the high-pressure pump and the fuel injectors from wearing down against one another is your diesel flowing through them — they are made to very fine clearances.
Badly at the first, not at all at the second: that's petrol. The knocking comes from petrol being made not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication your system depends on, and any pump working on that mixture is wearing itself.
Put those together and the shape of the problem is clear. It's movement that causes the harm, not contact. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors beyond it.
Four scenarios we see around Fishpool: how bad is petrol in a diesel?
Fuelled but never started — the best it gets. That petrol is in your tank and only your tank, and the job is a drain and a flush where the vehicle sits. This is the one situation that can only truly occur at a forecourt, since anywhere else your car has been driven to get there.
Ignition on, or started for a moment. Once primed, the fuel system has drawn petrol out of the tank up to the fuel filter and the fuel lines. Still generally straightforward: drain, flush, and the fuel filter sorted.
Driven a couple of miles. Now your pump has spent those miles working on thinned fuel. Miles is only half of it; how hard it was driven matters just as much. Either way this work includes your tank, the lines, the filter and clean fuel through the whole circuit. The school run to St Luke's CofE Primary School is one thing. A run as far as Salford, under 10 miles away, is a very different task. So is any mileage on the M66, under a mile from Fishpool, where the motor has been working hard the whole time.
Driven until it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your engine reporting fuel that no longer runs like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Devon Street. Permanent damage is very uncommon if a vehicle is stopped soon, and the drain and flush that still come first deal with it.
Myths Fishpool motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing comes out when you top up — that tank simply carries more of the same mixture. That advice supposes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through finer components: that's how a current diesel handles its fuel, and so the lubrication matters 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 normally stops, because it will not run, and the harm stops with them. A diesel fed petrol normally starts, ticks over and drives away as if nothing has happened, whilst the pump grinds. 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 different issue. What petrol has thinned stays diluted, and the petrol remains in that tank anyway.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol lies in the fuel filter and lines, waiting to go straight back through the pump at the next start. It is also really risky to drain petrol into a can at the roadside.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol car at all. So the mistake runs one way.
Routine and your car falling out of step is when it takes place. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. A rushed fill en route to Kearsley with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it occurs. Your hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Fishpool drivers: how to prevent petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the pump's label; the colour is only a hint.
- The first fill in a new motor is the time to check the filler flap — inside it, or on the cap, many vehicles state the fuel they take.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, in a home with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new vehicle, say "diesel" aloud. Daft, perhaps, yet it works.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not take a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- As soon as you notice, stop: less petrol in that tank means a weaker mixture. What to do next doesn't change, though — still do not start it.
Put petrol in a diesel in Fishpool already?
The order of things is short, then. Leave it unstarted, with the ignition switched off too. If you are still at the forecourt — Tesco or anywhere else — ask the staff to help you roll it away from the petrol pump. Next, 0333 366 0103. We'll ask what was put in, roughly how much, and if it's been run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Fishpool has a page all for it.
One petrol in a diesel task around Fishpool costs more than another. Why?
An honest single price does not exist here: four scenarios, four separate jobs. Which of them you are in is chiefly what shifts the cost. Where the vehicle is counts too, and whether a van can safely reach it, after the proportion of petrol to what the tank takes.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Their replies are what change a range into one firm number.
About Fishpool itself
Fishpool is a suburban area in Greater Manchester, situated approximately 7 miles from Salford and 170 miles from London. Fishpool has a population of around 6573 people and is characterised by predominantly terraced housing. Fishpool sits at an elevation of 84 metres, in a gently sloping inland area near the communities of Redvales, Gigg, and Buckley Wells.
Fuel drain cover across Greater Manchester, Fishpool included
Our teams answering petrol in diesel calls around Fishpool, in the BL postcode area, equally work the spots near it, Redvales, Gigg and Buckley Wells included. Our technicians drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Fishpool and still at the pump?
Then you are in the best place there can be. Ring, and leave it turned off.