--- title: Petrol in a Diesel Car Bassingbourn — Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/bassingbourn-cambridgeshire/ location: Bassingbourn county: Cambridgeshire latitude: 52.077360 longitude: -0.058800 service: Petrol in a Diesel Car updated: 2026-10-09 --- # Bassingbourn: Petrol in a Diesel Car? How Worried to Be If it has not been started, you can worry far less than you likely are. Everyone around Bassingbourn starts with "have I ruined it?", and the honest answer is usually no: petrol resting inside your tank of a diesel remains harmless till priming, cranking or driving draws it into the system. To leave it that way, ring Petrol in Diesel then leave the motor switched off. The rest of this page sets out 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. ## What petrol in a diesel does to the motor Passing through an engine, diesel is doing two things at the same time. Before it ignites, it lubricates — then it burns. What keeps the surfaces inside your high-pressure pump and the fuel injectors from wearing against each other is the diesel flowing through them — they're designed to very fine gaps. Of those two jobs, petrol manages the first poorly and the second never. It's thinner than diesel and takes away the lubrication your fuel system rests on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the clattering comes from. Put these together and the shape of the issue is clear. Contact does not do the harm — movement does. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors beyond it. ## Bassingbourn, petrol in a diesel: four situations, from mild to significant The best case there can be: filled up, not once started. On a forecourt, and genuinely only there, the petrol is still confined to the tank — because everywhere else the vehicle was driven to get to it. The job is draining and flushing on the spot. A brief spell of running, or merely your ignition on. Petrol has come out of that tank and reached the filter and your lines, since the system has been bled. Drain, flush, see to the fuel filter: still normally straightforward. Driven a couple of miles. Now your pump has spent these miles running on thinned fuel. How hard your car was driven counts as much as how far, and this work takes in that tank, the lines, the fuel filter and fresh fuel through the whole system. The school run to Bassingbourn Primary School is one thing. Getting as far as Cambridge, under 15 miles away, makes a very different job — as does any distance on the A1(M), under 10 miles from Bassingbourn, with the motor labouring hard all the way. It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. The motor is telling you your fuel is no longer acting like diesel. Pull up wherever you are — the verge on Garden Place, a lay-by, a side street — then leave it where it is. Permanent damage is very rare if a car is pulled over soon, and the drain and flush-through that still come first deal with it. ## What Bassingbourn motorists 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 when you top up — the tank just holds more of the same mixture. That guidance supposes a diesel fuel system handles petrol by percentage. It does not. Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that's how a newer diesel moves its fuel, and so the lubrication counts for more, not less. "It starts, it drives, so there is no harm" — the myth that trips up most drivers than any other. Diesel in a petrol motor normally leaves a motor that won't run: the driver stops, and so does the damage. A diesel fed petrol normally starts, idles and drives away as though nothing has happened, while your pump grinds. Running is not the same as fine. "A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate fault. What petrol has diluted remains weakened, and the petrol stays inside that tank regardless. Once your engine has been run, part of the petrol is in your filter and the fuel lines, not that tank — and your next start sends it right back through the pump. So the myth "drain your tank yourself and you are sorted" does not stand up. And, a can of petrol drained by the roadside is truly hazardous. ## Why petrol in a diesel happens so easily A careless moment is rarely the cause, and nobody means to do it. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol motor. That is how the forecourt makes it easy. When routine and the car stop matching, it occurs. Courtesy car, hire car, or a motor that's brand new. One petrol and one diesel on the driveway of the same household. A familiar forecourt with the pumps in a different order. Fuelling up in a rush en route to Royston, 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. Add a back seat full of kids, a phone call or rain, and the hand wins. ## How to prevent petrol in a diesel at your next fill-up in Bassingbourn - The label is what counts, and so check the petrol pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt. - Many vehicles state the fuel type inside the filler flap or on the cap, and so check there on your first fill in any vehicle you don't know. - One of each in the home? Label the key to the diesel — a coloured fob, a sticker — since intending to remember is not enough. - Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It sounds silly and it does the trick. - Tuck the phone away. This is an easy mistake to make whilst you are thinking about something else. - Some diesels have a filler built to refuse 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 petrol pump. - As soon as you realise, stop: less petrol inside your tank means a thinner mix. What to do next doesn't change, though — still do not crank it. ## Put petrol in a diesel in Bassingbourn already? In that case, there is only a short order of things. Starting it is out, and so is turning on the ignition. Ask the staff to help you push it clear of the pump if you are still at the forecourt, whether that is Tesco or anywhere else. What went in, about how much, and if it's run: tell us those when you call 0333 366 0103. Say so if it was AdBlue rather than petrol: it is a separate fault, with its own page for Bassingbourn, because AdBlue brings corrosion and deposits instead of lost protection. ## Why one petrol in a diesel job in Bassingbourn costs more than another There's no honest single quote for this, because the four scenarios above are four different tasks. Chiefly, the cost shifts with which one you're in. The proportion counts next, meaning how much of your tank is petrol, and then the position of the vehicle and whether reaching it is safe for our van. That is why our engineers ask three questions before quoting rather than after: what was put in, how much, and whether it's run. Those replies are what turn a range into one firm number. ## About Bassingbourn, for a moment Bassingbourn is a village in Cambridgeshire, situated in the eastern part of the county, approximately 11.6 miles from Cambridge. Bassingbourn sits in a low-lying area at an elevation of around 30 metres, near the villages of Kneesworth and Litlington. Bassingbourn has a population of around 1177 people, predominantly living in semi-detached housing. Bassingbourn is also within commuting distance of London, being about 39.5 miles from the capital. ## Across Cambridgeshire and in Bassingbourn: fuel drain cover Kneesworth, Litlington and Dyers Green are among the locations around Bassingbourn that the same teams work, answering petrol in diesel jobs across Bassingbourn's SG postcode area. No need to move your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain. ## At the petrol pump around Bassingbourn, right now? In that case, you could not be in a better position. Keep it off. Ring.