--- title: Petrol in a Diesel Car Fisherrow — Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/fisherrow-east-lothian/ location: Fisherrow county: East Lothian latitude: 55.942670 longitude: -3.061600 service: Petrol in a Diesel Car updated: 2026-10-06 --- # Petrol in a Diesel Car in Fisherrow: How Worried Should You Be? Probably less than you are now — provided nobody has started the vehicle. Until the ignition primes your pump, your starter turns, or the car is driven, petrol in a diesel tank simply waits there and does no harm. Which makes the truthful reply to the first Fisherrow question — "have I ruined it?" — usually no. To leave the car like that, phone Petrol in Diesel and leave the motor switched off. Read on for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and the way to make sure you don't do it again. ## Petrol in a diesel: what does it do to the engine? On its way through an engine, diesel does two jobs. Before it burns, it protects — and then it burns. Extremely fine tolerances are built into your injectors and your high-pressure pump, and only the diesel running through keeps their surfaces from grinding together. Petrol handles the first job poorly and the second not at all. It's runnier than diesel and takes away the lubrication your fuel system rests on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from. Combined, those leave the shape of the trouble plain. Contact does not do the harm — circulation does. A tank with petrol in it is a fuel issue. After the pump has been labouring on that petrol, a mechanical fault has started: whatever is shed by a pump that is grinding is carried onward to your injectors with your fuel. ## How bad is petrol in a diesel? Four situations we see in Fisherrow Filled but not once started — the best it gets. Only the tank has petrol in it, so the job is emptying that tank and purging your system where the car stands. This situation can only really occur on a forecourt: anywhere else, the car got there by being driven. Ignition on, or started for a moment. Petrol has come out of your tank and reached the filter and the fuel lines, because your system has been bled. Drain, flush, see to the filter: still normally simple. The pump now spent a couple of miles on diluted fuel — that's what driving the car does. Mileage is only half of it; how hard it was driven counts equally. Either way this work includes that tank, your lines, your filter and clean fuel through the entire circuit. The school run to the local primary school is one thing. Very different a second time: a trip to Edinburgh, under 10 miles away, or some mileage on the M8, under 10 miles from Fisherrow, where the motor never stopped running hard. Driven on until it protested — knocking, smoke, an uneven idle, a dead throttle. The motor is telling you your fuel is no longer acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Campie Lane. What goes first is still the drain and flush, and that sorts it out, with long-term damage very uncommon if a vehicle is pulled over soon. ## What Fisherrow people get told about petrol in a diesel — and the myths in it "Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice presumes. If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." At higher pressure, through finer components: that's how a modern diesel moves its fuel, so the protection counts more, not less. This is the one that fools people. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol motor and it usually will not run, and so the motorist stops — and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump wears. Running doesn't mean fine. Myth: "Add some two-stroke oil and drive it home." It is an outdated workaround for a different problem. That petrol is still inside that tank after that, and what it has diluted is not put back. If the motor has run, part of the petrol sits in the filter and your lines, not that tank — and your next start sends it straight back through your pump. So the myth "drain your tank yourself and you're sorted" does not stand up. And, a can of petrol filled by the roadside is truly dangerous. ## Petrol in a diesel: how does it take place? On purpose? Never. Through carelessness? Seldom, if ever. One way only, because of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol motor. That is how the forecourt makes it straightforward. It takes place when routine and the car stop matching. A motor that's new to you — hired, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. Fuelling up in a hurry on the way to Musselburgh, with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it happens. Throw in a back seat full of children, a phone call or rain, and the hand takes over. ## Next time you fill up around Fisherrow: avoiding petrol in a diesel - Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what counts. - Plenty of vehicles state the fuel inside the filler flap or on the cap, and so check there on your first fill in a vehicle you don't know. - Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a house has one of each. So mark it. - It seems daft and it works: on your 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 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 block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the pump. - Spotting it mid-fill? Stop at once. A weaker blend results from less petrol in the tank, but your next step remains the same: do not fire it up. ## Fisherrow: already put petrol in a diesel? Then the order of things is brief. Leave it unstarted, with the ignition off too. Yet on the forecourt, at Tesco or anywhere else? Ask the attendants to help you roll the car away from the petrol pump. Then ring 0333 366 0103 and tell us what went in, about how much, and whether it has run. Corrosion and deposits are the issue with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Fisherrow page. ## What makes one Fisherrow petrol in a diesel job cost more than the next The four situations above are four separate tasks, so no single price for this would be fair. What shifts your cost is mostly which of them you are in. Where the car is matters too, and whether a van can safely get to it, after the ratio of petrol to what that tank holds. Three queries come first, before quoting, rather than after — what was put in, how much, has it run — and that is the reason. Those replies change a range into a straight figure. ## About Fisherrow Fisherrow is a coastal suburban area in East Lothian, situated near the city of Edinburgh and close to the Firth of Forth. Fisherrow has a relatively low elevation of around 8 metres, reflecting its seaside location. Fisherrow is characterized by its predominantly flat-type housing, which is common in many Scottish coastal towns. Fisherrow is also near several other local places, including Stoneyhill Steading and Newhailes. ## Fuel drain cover across East Lothian, Fisherrow included Our vans answering petrol in diesel call-outs in Fisherrow, in the EH postcode area, also work the places around it, Stoneyhill Steading, Newhailes and Musselburgh included. We drain wherever the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us. ## At the petrol pump around Fisherrow, still? Nothing beats it: that's where you are. Turned off it remains; then ring.