--- title: Explained: Petrol in a Diesel Car Townsend canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/townsend-somerset-ta16-5/ location: Townsend county: Somerset latitude: 50.914370 longitude: -2.789420 service: Petrol in a Diesel Car updated: 2026-10-04 --- # Townsend: Petrol in a Diesel Car? How Worried to Be Unstarted? Then less anxious than you probably feel. Petrol resting in a diesel tank does nothing to the motor until something pulls it through the system — the ignition priming the pump, the starter, or the drive itself. So the fair answer to the first question anyone in Townsend asks, "have I wrecked it?", is normally no. Leave the motor off and phone Petrol in Diesel — that keeps it that way. Below, this page sets out 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 the motor Two tasks fall to diesel on its journey round a motor. Before it burns, it lubricates — then it ignites. Made to very fine gaps, your injectors and the pump depend on your diesel moving through them to keep their surfaces from wearing against one another. The second task petrol does not do at all, and the first it does badly. The rattling comes from petrol being made not to ignite when compressed, which is precisely the reverse 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 working on that mixture is wearing itself. Put those together and the shape of the trouble is plain. The damage is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem begins. ## How bad is petrol in a diesel? Four scenarios we see in Townsend Fuelled up, never started. The best case there can be. On a forecourt, and really only there, that petrol is still limited to your tank — because anywhere else the car was driven to reach it. The task is draining and purging on the spot. Ignition on, or started for a moment. Petrol has left the tank and got to your filter and the lines, since the fuel system has been primed. Drain, flush, deal with the filter: still usually straightforward. Driven a few miles. Now the pump has spent those miles running on diluted fuel. Mileage is only half of that; how hard it was driven counts equally. Either way this work runs to the tank, the lines, the fuel filter and clean fuel through the entire system. Driving the kids to Merriott Primary School is one sort of trip. A run as far as Wells, under 25 miles away, is a very different task. So is any distance on the M5, under 15 miles from Townsend, where the motor has been working hard throughout. Driven till it complained. Rattling, a ragged idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer acts like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Higher Street. Permanent damage is very uncommon if a vehicle is pulled over early, and the drain and flush-through that still go first deal with it. ## Stories Townsend people hear about petrol in a diesel False: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mix is all you get, because topping up takes out nothing. That advice assumes a diesel fuel system handles petrol by percentage. It doesn't. Myth: a modern diesel copes with a bit of petrol. Rather, the reverse. Lubrication matters more on current diesels, not less, since their fuel passes through more precise parts at higher pressure. One myth that catches people off guard: if it starts and drives, it must be unharmed. The driver of a petrol engine fed diesel normally has no choice but to stop, 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, which it usually does; meanwhile your pump grinds. Fine and running are not the same at all. An outdated fix for a separate issue is behind this one. Myth: "Add some two-stroke oil and drive the car home." What petrol has diluted remains weakened, and the petrol remains in your tank regardless. The next start draws petrol back round your pump out of the fuel lines and the filter, where some of it sits once the motor has run. That is why a DIY tank drain doesn't leave you sorted — a myth. On top of that, petrol drained into a can by the road is truly hazardous. ## How it happens: petrol in a diesel Nobody does it on purpose, and it is rarely carelessness. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it easy, and the mistake runs one way. Routine and the vehicle getting out of step is how it happens. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. Your ordinary forecourt, its pumps now in a different order. Fuelling up in a hurry on the way to Crewkerne, with a train to catch. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. The hand does what it has always done when you add rain, a phone call or a back seat full of kids. ## How to avoid petrol in a diesel on your next fill-up around Townsend - The label is what matters, so check the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt. - Many vehicles state the fuel type inside your filler flap or on the cap, so check it on the first fill in a car you don't know. - Label your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember. - "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds silly. It works. - Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away. - Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and aftermarket devices are available for the rest. Count it as a backstop, then keep checking the pump. - Noticing it halfway? Stop at once. A weaker mix follows from less petrol inside your tank, but your next step stays the same: don't fire it up. ## Townsend: already put petrol in a diesel? In that case, there is just a short order of things. Do not start it, and don't turn your ignition on. Ask the attendants to help you roll it clear of the petrol pump if you're still at the forecourt, whether that's Texaco or anywhere else. Ring 0333 366 0103 next, with three facts — your fuel, the approximate quantity, and whether it's run. AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate problem — Townsend has a page all for it. ## Townsend petrol in a diesel tasks: why one costs more than another Four different tasks lie behind the four scenarios above — which is why there's no honest single price. What shifts the cost is mostly which of them you're in. The proportion counts next, meaning how much of your tank is petrol, followed by the position of the car and whether getting to it is safe for our van. That's why our engineers ask three queries before costing rather than after: what was put in, how much, and if it's run. Given the replies, you get a straight figure rather than a range. ## About Townsend, for a moment Townsend is a suburban area in inland Somerset, situated approximately 54 metres above sea level. Townsend lies near the towns of Merriott and Wells, and is part of a network of small settlements including Merriottsford and Furringdons Cross. Townsend has a population of around 929 people and predominantly features semi-detached housing. ## Fuel drain cover across Somerset, Townsend included Merriott, Merriottsford and Furringdons Cross are among the locations near Townsend that the same vans work, answering petrol in diesel calls across Townsend's TA postcode area. The vehicle doesn't need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive. ## Townsend: still at the petrol pump? Nothing beats it: that's where you are. Switched off it stays; then phone.