--- title: Explained: Petrol in a Diesel Car Cheddar canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/cheddar-somerset/ location: Cheddar county: Somerset latitude: 51.275440 longitude: -2.776580 service: Petrol in a Diesel Car updated: 2026-10-10 --- # Petrol in a Diesel Car in Cheddar: How Worried Should You Be? If it has not been started, worry far less than you probably are. Till your ignition primes your pump, your starter turns, or your car is driven, petrol in a diesel tank simply waits there and does nothing. Which means the truthful reply to the first Cheddar question — "have I ruined it?" — normally no. To keep the car that way, phone Petrol in Diesel and leave your engine alone. Further down, you will find what petrol really does inside a diesel, how far it may have gone, and how to stop it happening to you a second time. ## What petrol in a diesel does to your engine Two jobs fall to diesel on its journey round a motor. Before it ignites, it lubricates — and then it burns. What keeps the surfaces inside the high-pressure fuel pump and the injectors from grinding against each other is your diesel flowing through them — they are designed to very fine tolerances. Of those two jobs, petrol manages the first poorly and the second never. It's runnier than diesel and strips away the lubrication the fuel system depends on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the rattling comes from. Put these together and the shape of the issue is plain. Not contact but circulation is what does the harm. Any tank with petrol in it is a fuel fault. Once your pump has been labouring on that petrol, a mechanical issue has begun: whatever is shed by a pump that is grinding travels downstream to your injectors with your fuel. ## Petrol in a diesel around Cheddar: how serious is it? Four situations Fuelled, and not started: nothing beats it. Just that tank has petrol in it, so the job is clearing that tank and purging the system where the car sits. This scenario can only really occur on a forecourt: anywhere else, the car got there by being driven. A moment's running, or just the ignition on. The system has been primed, so petrol has left that tank and reached your filter and your lines. That's generally still an easy task — a drain, a flush, and the filter dealt with. Some miles driven, and your pump has spent each of them running on thinned fuel. Tank, lines, filter, then fresh fuel put through the entire system: that is the work, and the way your car was driven counts as much as the miles. On the school run to Cheddar First School, the mileage is small. Driving as far as Wells, under 10 miles away, makes a very different job — as does any mileage on the M5, under 10 miles from Cheddar, with your engine working hard all the way. It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. That's your motor telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on Union Street, a lay-by, a side street — then leave the car there. What goes first is still the fuel drain and flush-through, and that sorts it out, with long-term damage very unusual if a car is pulled over early. ## Stories Cheddar motorists hear about petrol in a diesel Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that advice supposes. If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." A modern diesel runs its fuel through finer parts at higher pressure, which makes the protection count more, not less. This is the one that catches people. Myth: "If it starts and drives, there is no damage done." Feed diesel to a petrol engine and it generally will not run, so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and pulls away like nothing has happened — all while its pump is wearing. Being able to run isn't the same as being fine. Not so: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another fault. What petrol has diluted stays diluted, and that petrol stays in your tank regardless. If your engine has been run, part of that petrol is in the filter and the lines, not the tank — and the next start pulls it right back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. On top of that, petrol drained into a can by the road is genuinely dangerous. ## How does petrol in a diesel happen? It's rarely carelessness, and nobody does it on purpose. A diesel nozzle mostly will not fit a petrol motor, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in one direction. It takes place when habit and the vehicle stop matching. A new motor, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. A forecourt you know, only with its pumps laid out differently. A rushed fill en route to Worle with a train to catch. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Renault Clio for the first time. Throw in rain, a phone call or a back seat full of kids, and your hand does what it has always done. ## Cheddar drivers: how to avoid petrol in a diesel next time - Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Read the petrol pump's label; the colour is just a clue. - The first fill in an unfamiliar car is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use. - One of each in the house? Mark the key to your diesel — a coloured fob, a sticker — since meaning to remember is not enough. - Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump. It seems daft and it does the trick. - Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone away. - Some diesels have a filler designed to block a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump. - As soon as you realise, stop: less petrol inside that tank makes a weaker blend. What to do next does not change, though — still don't fire it up. ## Cheddar: already put petrol in a diesel? The order of things is short, then. Starting it is out, and so is turning on the ignition. If you are still on the forecourt — Murco or anywhere else — ask the attendants to help you push the vehicle clear of the pump. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it has been run. AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate issue — Cheddar has a page just for it. ## What makes one Cheddar petrol in a diesel job cost more than the next The four scenarios above are four separate jobs, so no single price for this would be fair. Mostly, your cost moves with which situation you are in. After that it's the ratio — how much petrol got in against how much the tank takes — and after that where the vehicle is and whether our van can get to it safely. Three questions come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number. ## About Cheddar itself Cheddar is a village situated in the Somerset countryside, beside the River Yeo and near the Mendip Hills. Cheddar sits at a low elevation of around 13 metres, close to the city of Wells and surrounded by smaller settlements like Lippiatt and Hillfield. Cheddar has a mix of housing types, with semi-detached homes being particularly common. Cheddar is located approximately 115 miles west of London, making it a relatively rural community in the South West of England. ## Fuel drain cover across Somerset, Cheddar included Lippiatt, Hillfield and Barrows are among the locations around Cheddar that the same teams work, answering petrol in diesel calls across Cheddar's BS postcode area. We drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us. ## Cheddar: still at the petrol pump? Nothing beats it: that is where you now are. Keep it off. Phone.