--- title: Petrol in a Diesel Car Cotmaton — Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/cotmaton-devon/ location: Cotmaton county: Devon latitude: 50.679140 longitude: -3.248830 service: Petrol in a Diesel Car updated: 2026-10-12 --- # Petrol in a Diesel Car in Cotmaton: How Worried Should You Be? Unstarted? Then less anxious than you probably feel. "Have I wrecked it?" is the first question anyone around Cotmaton asks, and the truthful answer is normally no, since petrol left in a diesel tank hurts nothing till it's drawn through the fuel system — by ignition priming, by your starter, or by being driven. To keep the vehicle like that, call Petrol in Diesel then leave the engine switched off. Further down, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you again. ## Inside your engine: what petrol in a diesel does Two tasks fall to diesel on its journey round a motor. It burns, and before it burns it protects. Your high-pressure pump and the fuel injectors are designed to very fine clearances, and your diesel passing through them is what stops those surfaces from grinding against one another. Petrol does the first task poorly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump on that mixture wearing itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking. The shape of the problem is clear when you put those together. It's movement that causes the harm, not contact. Petrol in the tank is a fuel fault. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream. ## Cotmaton, petrol in a diesel: four situations, from mild to serious The best case there is: filled up, not once started. Being at a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol held in that tank alone, it's emptied and rinsed on the spot, and nothing more is needed. Your ignition turned on, or a brief start. Once primed, your system has pulled petrol out of that tank up to the fuel filter and the fuel lines. Drain, flush, see to the filter: still normally straightforward. Driven a few miles. Now the pump has spent these miles running on diluted fuel. How hard your car was driven counts as much as how far, and this work takes in that tank, the fuel lines, the filter and fresh fuel through the entire system. A school run to Sidmouth Church of England (VA) Primary School is one matter. Any mileage on the M5, under 10 miles from Cotmaton, means your engine working hard throughout, and a run to Exeter, under 15 miles away, is a very different job as well. Knocking, an uneven idle, smoke, a throttle gone soft: driven till it complained. The fuel isn't acting like diesel any more, and your motor is saying so. Stop where you are — on the verge on Cotlands, at the kerb, down a side road — and do not move it. What comes first is still the fuel drain and flush-through, and that takes care of it, with permanent damage very uncommon when a vehicle is pulled over soon. ## What Cotmaton drivers get told about petrol in a diesel — and the stories in it 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 bigger tank, still the same mixture. A diesel fuel system does not accept petrol by percentage in the way that advice presumes. Not so: a newer diesel copes with a bit of petrol. Rather, the opposite. At higher pressure, through finer components: that's how a current diesel handles its fuel, and so the lubrication matters for more, not less. Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. Any petrol engine fed diesel generally won't run, so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and drives away as if nothing has happened — all while its pump wears. Running does not mean fine. Myth: "Add some two-stroke oil and drive the car home." It is an old workaround for a different fault. What petrol has diluted stays diluted, and that petrol stays inside that tank anyway. The next start draws petrol back round your pump out of the fuel lines and the fuel filter, where some of it sits once the motor has run. That is why a DIY tank drain does not sort it — a myth. Clearing petrol into a can by the kerbside is also truly risky. ## How does petrol in a diesel occur? Nobody does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way. When habit and the vehicle stop matching, it takes place. Courtesy car, hire car, or a motor that's new. Two vehicles on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Feniton. Precisely the moment it occurs: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it always has. ## Next time you fill up in Cotmaton: preventing petrol in a diesel - Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the pump's label; the colour is only a clue. - In a vehicle you do not know, look inside the flap over the filler or at the cap before the first fill: plenty of motors state the fuel there. - One of each in the household? Label your key to the diesel — a bright fob, a sticker — because intending to remember isn't enough. - Before the nozzle comes off the petrol pump the first time you fuel a hired or new car, say "diesel" aloud. Daft, yes, yet it does the trick. - Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else. - Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, then keep reading the pump. - Less petrol makes a weaker mixture, and so stop the moment you realise — though remembering that the next stage is unchanged. It's still not to crank it. ## Already put petrol in a diesel in Cotmaton? In that case, there's only a short order of things. Do not turn the ignition on, and do not fire it up. Ask the attendants to help you push it away from the petrol pump if you're still at the forecourt, whether that's the nearest petrol station or somewhere else. What was put in, about how much, and whether it has run: tell us that when you phone 0333 366 0103. Corrosion and deposits are the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Cotmaton page. ## What makes one Cotmaton petrol in a diesel task cost more than the next There's no honest single quote for this, since the four situations above are four separate tasks. Which of them you are in is chiefly what moves your cost. Beyond that it is the ratio — how much petrol got in against how much the tank holds — and after that where your car is and whether a technician can get to it safely. That is why our technicians ask three questions before quoting rather than after: what got in, how much, and whether it has run. With those replies, you get a straight figure instead of a range. ## About Cotmaton itself Cotmaton is a suburban area located on the coast of Devon, with an elevation of 38 metres above sea level. Cotmaton sits near the cities of Exeter and the towns of Sidmouth, Western Town, and Eastern Town, and is characterized by its predominantly detached housing. Cotmaton is a relatively small community, with a population of approximately 1566 residents. Cotmaton is situated in a scenic coastal area, with the city of Exeter being the nearest major urban centre, approximately 12.8 miles away. ## Fuel drain cover around Cotmaton and across Devon Petrol in diesel call-outs in Cotmaton — part of the EX postcode area — go to vans that also cover the places about it, Western Town, Sidmouth and Eastern Town included. The vehicle does not need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway. ## In Cotmaton and still at the petrol pump? In that case, you couldn't be in a better place. Call, and keep it turned off.