--- title: Tetbury: Petrol in a Diesel Car, Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/tetbury-gloucestershire/ location: Tetbury county: Gloucestershire latitude: 51.636960 longitude: -2.159420 service: Petrol in a Diesel Car updated: 2026-10-16 --- # How Worried Should You Be? Petrol in a Diesel Car in Tetbury If it has not been started, worry far less than you likely are. Everyone around Tetbury starts with "have I ruined it?", and the fair answer is generally no: petrol resting in your tank of a diesel remains harmless until priming, cranking or driving draws it into your fuel system. Keep it that way: leave the engine off then ring Petrol in Diesel. What petrol really does to a diesel, how to judge how far it's travelled, and how to stop it from happening a second time: that is the rest of this page. ## Inside the engine: what petrol in a diesel does Two tasks fall to diesel on its journey round a motor. Lubricating comes before burning; it does both. Your high-pressure pump and the fuel injectors are built to extremely fine gaps, and your diesel passing through them is what keeps those surfaces from wearing against each other. The second task petrol does not do at all, and the first it does poorly. The clattering comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the system rests on, and any pump running on that mix is wearing itself. Put these together and the shape of the issue is clear. The harm is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel issue. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the injectors further on. ## How serious is petrol in a diesel? Four situations we see around Tetbury Filled up, not once started. The best case there is. Only your tank has petrol in it, so the job is draining that tank and cleaning the fuel system where the vehicle stands. This situation can only truly occur at a forecourt: anywhere else, the vehicle got there by being driven. Ignition on, or started for a second. Once primed, the system has pulled petrol out of that tank up to the fuel filter and the lines. Usually nothing more than draining, rinsing and seeing to the filter, and so still easy. A couple of miles driven, and your pump has spent each of them labouring on weakened fuel. Tank, lines, filter, then clean fuel run through the entire system: that's this work, and the way your car was driven counts as much as the miles. On the school run to St Mary's Church of England Primary School, the distance is small. Very different once more: a run to Gloucester, under 25 miles away, or some miles on the M4, under 10 miles from Tetbury, where your engine kept running hard. Driven until it complained. Knocking, a ragged idle, smoke, a throttle that has gone soft. That's the motor telling you its fuel has stopped behaving like diesel. Whether it's the verge on Church Street, a lay-by or a side street, stop there then leave it. What comes first is still the fuel drain and flush, and that takes care of it, with long-term damage very unusual if a car is stopped quickly. ## What Tetbury people get told about petrol in a diesel — and the myths in it 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're left with a fuller tank, still the same mixture. That guidance supposes a diesel fuel system handles petrol by percentage. It does not. "Current diesels can handle a little petrol" — a myth, and closer to the opposite. A modern diesel runs its fuel through smaller components at higher pressure, which makes the lubrication count more, not less. One myth that catches drivers out: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel normally stops, since it will not run, and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump grinds. Fine and running are not the same thing. Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a distinct problem. It doesn't put back what petrol has diluted, and that petrol is still in your tank afterwards. "Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in your filter and lines, waiting to go right back through the pump at the next start. On top of that, petrol emptied into a can by the road is truly hazardous. ## How does petrol in a diesel take place? A careless moment is seldom the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally will not go into a petrol car at all. So the mistake runs one way. Habit and your car getting out of step is how it happens. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the drive of the same household. A forecourt you know, only with its pumps arranged differently. A hurried fill on the way to Kemble with a train to catch. Years of petrol motors behind you, a diesel Ford Focus in front of you at the forecourt for its first tank — that is when. With rain, a call coming in, or children to deal with, your hand just does what it always has. ## How to avoid petrol in a diesel on your next fill-up around Tetbury - 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 clue. - Many motors state the fuel inside your filler flap or on the cap, and so check there on your first fill in a motor you don't know. - A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a household with one of each. - It sounds daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. - Mistakes like this are easy to make whilst your mind is on something else, and so your phone goes away. - Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump. - Spotting it halfway? Stop there and then. A thinner blend follows from less petrol inside your tank, yet the next stage stays the same: don't crank it. ## Petrol already in a diesel around Tetbury? Start here Then the order of things is short. Starting it is out, and so is turning on your ignition. Ask the staff to help you roll it clear of the petrol pump if you're still on the forecourt, whether that is Tesco or somewhere else. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run. Corrosion and deposits are the problem with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and read its own Tetbury page. ## One petrol in a diesel job around Tetbury costs more than another. Why? Four different jobs lie behind the four situations above — which is why there is no fair single price. The situation itself does most of the work of moving your cost. The ratio matters next, meaning how much of your tank is petrol, followed by the position of the vehicle and whether reaching it is safe for our van. Before any quote, not after, come three questions: the fuel that got in, the quantity, and if it's run. That's why. A range turns into a straight figure when those answers are in. ## About Tetbury itself Tetbury is a small town in Gloucestershire, situated on the banks of the River Avon at an elevation of around 125 metres. Tetbury lies in the Cotswold hills, near the villages of Northfield, Tetbury Upton, and Long Newnton, and is approximately 16 miles southwest of Gloucester. Tetbury has a population of around 6744 people, predominantly living in semi-detached housing. Tetbury is also within commuting distance of larger cities, being around 87 miles west of London. ## Fuel drain cover in Tetbury and across Gloucestershire Northfield, Tetbury Upton and Long Newnton are among the locations around Tetbury that the same vans work, answering petrol in diesel call-outs across Tetbury's GL postcode area. No need to bring the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain. ## In Tetbury and still at the petrol pump? Nothing beats it: that is where you are. Switched off it stays; then phone.