--- title: Explained: Petrol in a Diesel Car Portway canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/portway-somerset/ location: Portway county: Somerset latitude: 51.120590 longitude: -2.734450 service: Petrol in a Diesel Car updated: 2026-10-15 --- # Petrol in a Diesel Car in Portway: How Worried Should You Be? Less than you likely are, provided it hasn't been started. Until the ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which means the honest reply to the first Portway query — "have I wrecked it?" — usually no. Leave your engine off then ring Petrol in Diesel — that keeps it that way. The remainder of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again. ## Petrol in a diesel: what does it do to the motor? Passing through an engine, diesel does two things at once. It protects first, and after that does it burn. Extremely fine tolerances go into the injectors and the high-pressure pump, and just your diesel flowing through stops their surfaces grinding together. Poorly at the first, not at all at the second: that is petrol. It is thinner than diesel and takes away the protection your fuel system rests on, so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from. Together, those leave the shape of the problem plain. Contact does not do the harm — circulation does. Where that petrol is only inside that tank, it's a problem of fuel, nothing more. The beginning of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors downstream. ## Petrol in a diesel in Portway: how bad is it? Four situations Filled up, not once started. The best case there can be. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held inside that tank alone, it's cleared and rinsed right where it stands, and nothing more is needed. Ignition on, or started for a moment. Once primed, your system has pulled petrol out of your tank up to the fuel filter and the fuel lines. Still normally simple: drain, flush, and the filter dealt with. The pump now spent a few miles on diluted fuel — that's what driving it does. Mileage is only half of it; how hard it was driven counts equally. Either way the work runs to the tank, the lines, the fuel filter and fresh fuel through the entire system. On the school run to Hindhayes Infant School, the distance is short. Any distance on the M5, under 15 miles from Portway, means your engine has worked hard throughout, and a run to Wells, under 10 miles away, is a very different task as well. Driven on until it protested — clattering, smoke, a ragged idle, a soft throttle. That's the motor telling you its fuel has stopped behaving like diesel. Pull up where you are — on the verge on Portway, at the kerb, down a side road — and don't move it again. A vehicle pulled over early very seldom has lasting damage, since the drain and the flush-through, which still come first, take care of it. ## Portway motorists and that petrol in a diesel stories 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 when you top up — that tank just carries more of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, whatever that guidance assumes. "Modern diesels can handle a little petrol" — a myth, and nearer the opposite. A current diesel runs its fuel through finer components at higher pressure, which makes the protection count more, not less. "It starts, it drives, and so there is no harm" — the myth that catches more motorists than any other. Diesel in a petrol motor usually leaves a motor that won't run: the motorist stops, and so does the damage. Whilst your pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Running does not mean fine. Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a distinct issue. None of what petrol thinned is put back by it — and afterwards, the tank still holds that petrol. If your engine has run, part of the petrol is in the filter and your lines, not the tank — and the next start sends it straight back through the pump. So the myth "drain your tank yourself and you are sorted" does not stand up. Besides, petrol emptied into a can by the road is genuinely hazardous. ## Petrol in a diesel: how does it happen? Carelessness is rarely the cause, and no one means to do it. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol vehicle. That is how the forecourt makes it easy. It takes place when habit and the car stop matching. A vehicle that's new to you — hired, on loan as a courtesy car, or brand new. Two cars on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. A rushed fill on the way to Castle Cary with a train to catch. Years of petrol motors behind you, a diesel Renault Clio in front of you on the forecourt for its first tank — that is when. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of children. ## Next time you fill up in Portway: preventing petrol in a diesel - Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is just a hint. - In a car you don't know, look inside the flap over your filler or at the cap before the first fill: many motors print the fuel type there. - A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, in a household with one of each. - It sounds daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. - Whilst you're thinking about something else, this is an easy mistake to make — so put your phone away. - A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop checking the petrol pump. - Stop as soon as you notice. Less petrol inside your tank means a thinner mixture. It does not change what to do next, which is still not to crank it. ## Put petrol in a diesel around Portway already? The order of things is short, then. Starting it is out, and so is switching on your ignition. If you're still on the forecourt — Sainsbury's or anywhere else — ask the attendants to help you roll the vehicle away from the pump. Phone 0333 366 0103 next, with three answers — your fuel, the rough amount, and whether it's run. Say so if it was AdBlue instead of petrol: it is a different fault, with its own page for Portway, since AdBlue brings corrosion and deposits rather than lost lubrication. ## What makes one Portway petrol in a diesel task cost more than the next There's no fair single price for this, since the four scenarios above are four separate jobs. The situation itself does most of the work of moving your cost. Where the vehicle is matters too, and whether a van can safely get to it, after the proportion of petrol to what your tank takes. Ahead of any quote, not after, we ask three questions: your fuel that was put in, its amount, and whether it's run. That's why. The replies turn a range into a straight figure. ## About Portway itself Portway is a suburban area in Somerset, situated inland at an elevation of 27 metres, approximately 7 miles from the city of Wells. Portway is characterized by its predominantly semi-detached housing stock, reflecting the typical residential development patterns of the region. Portway sits near several smaller settlements, including Middle Leigh, Overleigh, and Lower Leigh, and is home to a population of around 3339 residents. Portway is located in the South West of England, about 115 miles west of London. ## Across Somerset and around Portway: fuel drain cover Portway sits in the BA postcode area, and our teams that answer petrol in diesel call-outs there work the locations near it as well — Middle Leigh, Overleigh and Lower Leigh among them. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work. ## Portway: still at the pump? The best position there is, then — that's where you are. Keep the car switched off, and ring.