Lochyside: Petrol in a Diesel Car? How Worried to Be
Provided it hasn't been started, worry less than you probably are. Everyone in Lochyside begins with "have I ruined it?", and the honest answer is usually no: petrol resting inside that tank of any diesel remains harmless till priming, cranking or driving pulls it into your fuel system. Leave the motor off and call Petrol in Diesel — that is how you keep it like that. Read on for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and ways to make sure you don't do it again.
Inside the engine: what petrol in a diesel really does
Passing through an engine, diesel does two jobs at once. It lubricates first, and only then does it burn. Very fine gaps go into the fuel injectors and the high-pressure pump, and only your diesel running through keeps their surfaces from grinding together.
The second job petrol doesn't do at all, and the first it does badly. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the lubrication your fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any rattling comes.
Taken together, they make clear what shape the issue takes. Not contact but movement is what causes the harm. Where the petrol is only in that tank, it's a problem of fuel, nothing more. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
How bad is petrol in a diesel? Four situations our engineers see in Lochyside
The best case there is: filled up, not once started. That petrol is inside the tank and only that tank, and the task is a drain and a flush where the vehicle sits. This is the one scenario that can only really occur at a forecourt, as anywhere else your car has been driven to get there.
Started for a second, or just the ignition on. The system has been bled, so petrol has left the tank and got to the fuel filter and the fuel lines. Usually nothing more than clearing, flushing and sorting your filter, so still easy.
Those few miles on the road meant the pump labouring on fuel diluted by petrol the whole way. How hard the vehicle was driven counts as much as how far, and this work takes in your tank, the fuel lines, your filter and fresh fuel through the whole system. Driving the kids to the local primary school is one sort of trip. Any miles on the M9, over 50 miles from Lochyside, means your engine working hard throughout, and a run to Inverness, over 50 miles away, makes a very different job as well.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't acting like diesel any more, and the motor is saying so. Stop on the spot — on the verge on Kilmallie Road, at the kerb, down a side road — and do not move it again. The drain and flush-through still come first, and they take care of it: when a car is stopped early, permanent damage is very unusual.
Lochyside motorists and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you're left with a fuller tank, still the same mix. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice assumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through smaller components: that's how a newer diesel handles its fuel, and so the protection matters for more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up most drivers than any other. Any petrol motor fed diesel generally won't run, so the motorist stops and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst the pump grinds. A running engine does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It is an outdated workaround for a separate fault. It doesn't put back what petrol has diluted, and that petrol is still inside the tank afterwards.
The next start sends petrol back round the pump from the fuel lines and your filter, where some of it sits after the engine has been run. That's why draining the tank yourself does not sort it — a myth. It's also truly risky to drain petrol into a can at the roadside.
Petrol in a diesel: how does it occur?
It's rarely carelessness, and no one does it on purpose. 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, whilst a diesel nozzle mostly will not go into a petrol car at all. So the slip runs one way.
Routine and the vehicle falling out of step is when it happens. Any car that's new to you — a hire car, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps suddenly in a different order. Rushing for a train at Banavie and filling up en route. Years of petrol cars behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that is when. Your hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Avoiding petrol in a diesel next time you fill up around Lochyside
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is just a clue.
- Check the filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key when a house has one of each. So label it.
- It sounds daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a thinner blend, and so stop as soon as you realise — though remembering that the next step is unchanged. It's still not to start the car.
Already put petrol in a diesel around Lochyside?
Then the order of things is short. Do not turn your ignition on, and don't crank it. Yet on the forecourt, at Shell or anywhere else? Ask the staff to help you push the car clear of the petrol pump. Then ring 0333 366 0103 and tell us what was put in, about how much, 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 read its own Lochyside page.
What makes one Lochyside petrol in a diesel task cost more than the next
An honest single quote doesn't exist here: four scenarios, four separate jobs. Which of them you're in is chiefly what moves the cost. The ratio matters next, meaning how much of your tank is petrol, followed by the location of the car and whether getting to it is safe for a van.
What was put in, how much, and whether it has run — three questions our engineers ask before costing, not after, for precisely that reason. A range becomes a straight figure when those replies are in.
About Lochyside
Lochyside is a small coastal village in the Highland region of Scotland, situated near the shores of Loch Linnhe. Lochyside has a low elevation of around 3 metres, and its semi-detached housing stock is typical of many modern Scottish villages. Lochyside is located near several other small communities, including Camaghael, Caol, and Inverlochy, and is within commuting distance of the city of Inverness.
Across Highland and around Lochyside: fuel drain cover
Lochyside rests in the PH postcode area, and the vans that answer petrol in diesel call-outs there work the places near it as well — Camaghael, Caol and Inverlochy among them. We drain wherever the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the petrol pump in Lochyside, still?
Nothing beats it: that's where you now are. Turned off it remains; then ring.