--- title: Petrol in a Diesel Car Yeovil — Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/yeovil-somerset/ location: Yeovil county: Somerset latitude: 50.940770 longitude: -2.633520 service: Petrol in a Diesel Car updated: 2026-10-04 --- # Should You Worry? Petrol in a Diesel Car in Yeovil Far less than you probably are, if it has not been started. Petrol sitting in a diesel tank does nothing to your engine until something draws it through the fuel system — your ignition priming the pump, your starter, or driving on its own. So the truthful answer to the first question everyone in Yeovil asks, "have I wrecked it?", is usually no. To leave it like that, phone Petrol in Diesel and leave your motor alone. The rest of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time. ## Inside the engine: what petrol in a diesel really does On its way through an engine, diesel does two jobs. It protects first, and after that does it burn. The high-pressure pump and your injectors are designed to very fine tolerances, and your diesel passing through them is what stops those surfaces from wearing against one another. The second job petrol does not do at all, and the first it does badly. A pump running on a petrol blend is wearing itself out, because petrol is thinner than diesel and takes away the protection your fuel system relies 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 clattering starts. The shape of the trouble is clear once you put those together. Contact doesn't do the harm — movement does. Any tank with petrol in it is a fuel problem. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the injectors downstream. ## Four scenarios we see around Yeovil: how bad is petrol in a diesel? The best case there is: filled up, never started. The petrol is inside that tank and only the tank, and the job is a drain and a flush where the vehicle sits. This is the one situation that can only really happen at a forecourt, as anywhere else your car has been driven to get there. Started for a second, or only your ignition on. The system has been primed, and so petrol has left that tank and reached the filter and your lines. Still generally easy: drain, flush, and the fuel filter seen to. The pump now worked a few miles on diluted fuel — that's what driving the vehicle meant. Distance is only half of it; how hard it was driven counts just as much. Either way this work includes your tank, the fuel lines, the filter and fresh fuel through the entire system. Short trips, like the school run to St Gildas Catholic Primary School, are one thing. A run as far as Wells, under 25 miles away, is a very different job. So is any distance on the M5, under 25 miles from Yeovil, where your engine has been running hard throughout. Driven till it complained. Rattling, an uneven idle, smoke, a throttle that has gone soft. That's your engine telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on King George Street, a lay-by, a side street — and leave the car where it is. A car stopped early very seldom has permanent damage, because the fuel drain and the flush-through, which still go first, deal with it. ## Petrol in a diesel stories Yeovil people hear It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mixture is all it gives, since topping up removes nothing. The assumption behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong. Myth: a newer diesel copes with a bit of petrol. If anything, the reverse. More precise components and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication count more, not less. "It starts, it drives, and so there is no harm" — the myth that trips up more motorists than any other. The motorist of a petrol engine fed diesel normally has no choice but to stop, because it will not run, and the harm stops with them. Feed petrol to a diesel and it generally fires up, idles and drives away like nothing has happened — all while its pump wears. Being able to run isn't the same as being fine. "A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate fault. It doesn't put back what petrol has thinned, and that petrol is still in the tank after that. Myth: "Drain that tank yourself and you are sorted." After your engine has run, some of the petrol is no longer inside that tank: it is in the fuel filter and the lines, and it goes straight back through your pump at the next start. And, a can of petrol filled by the roadside is genuinely risky. ## How petrol ends up: petrol in a diesel On purpose? Never. Through carelessness? Rarely, if ever. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the slip runs one way. The moment habit stops matching the car is the moment it takes place. Courtesy car, hire car, or a vehicle that's new. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Fuelling up in a hurry on the way to Yeovil Pen Mill, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: precisely when it happens. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids. ## Avoiding petrol in a diesel next time you fill up around Yeovil - A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Go by the label on the petrol pump, not the colour. - Check the filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on your first fill in any vehicle you don't know. - Mark the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember. - Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It seems silly and it works. - Tuck the phone away. This is an easy mistake to make while you're thinking about something else. - A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for cars without one. They are a safety net, not a reason to stop reading the pump. - Less petrol means a weaker blend, and so stop the moment you notice — while remembering that the next step is unchanged. It is still not to fire it up. ## Yeovil: already put petrol in a diesel? Then the order of things is brief. Don't fire it up, and don't turn the ignition on. The attendants at the forecourt — whether at Tesco itself or wherever you filled up — will normally help roll it away from the pump if you ask. What went in, roughly how much, and if it has run: tell us that when you phone 0333 366 0103. Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Yeovil page. ## What makes one Yeovil petrol in a diesel job cost more than the next There's no fair single quote for this, since the four situations above are four different jobs. The situation itself does most of the work of moving your cost. The proportion counts next, meaning how much of that tank is petrol, and then the position of the car and whether getting to it is safe for our van. That is why we ask three queries before pricing instead of after: what was put in, how much, and whether it's run. The answers turn a range into a straight figure. ## About Yeovil itself Yeovil is a town in south Somerset, situated on the River Yeo at an elevation of around 54 metres. Yeovil lies near the Somerset Levels and the Mendip Hills, with nearby settlements including Crofton Park and New Town. Yeovil has a mix of housing types, but semi-detached homes are particularly prevalent in the town. Yeovil is located approximately 115 miles west of London and 18 miles south of Wells. ## Fuel drain cover in Yeovil and across Somerset The teams answering petrol in diesel calls around Yeovil, in the BA postcode area, equally work the locations around it, Crofton Park, Goar Knap and New Town among them. The car doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway. ## Yeovil: still at the petrol pump? In that case, you could not be in a better position. Leave it switched off, and ring.