--- title: Locksbottom: Petrol in a Diesel Car, Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/locksbottom-greater-london/ location: Locksbottom county: Greater London latitude: 51.368940 longitude: 0.058550 service: Petrol in a Diesel Car updated: 2026-10-09 --- # Locksbottom: Petrol in a Diesel Car? How Worried to Be Not started? Then less worried than you probably are. Everyone around Locksbottom begins with "have I ruined it?", and the honest answer is normally no: petrol resting inside the tank of any diesel stays harmless till priming, cranking or driving draws it into your fuel system. To keep the vehicle that way, ring Petrol in Diesel and leave your engine switched off. What petrol actually does to a diesel, how to gauge how far it's gone, and how to keep it from happening again: that is the remainder of this page. ## The engine and petrol in a diesel: what goes on Passing through a motor, diesel does two things at the same time. It combusts, and before it burns it protects. Made to very fine tolerances, your injectors and the pump depend on the diesel moving through them to stop their surfaces wearing against one another. Poorly at the first, not at all at the second: that's petrol. The rattling comes from petrol being designed 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 out the protection the system rests on, and any pump running on that mix is wearing itself. Seen together, they make clear the shape the issue takes. Not contact but circulation is what does the damage. A tank with petrol in it is a fuel fault. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors downstream, which is why a pump that has been working on that petrol is where a mechanical issue begins. ## How serious is petrol in a diesel? Four situations our engineers see in Locksbottom Filled up, never started. The best case there can be. Only the tank has petrol in it, and so the task is clearing your tank and flushing the fuel system where the vehicle stands. This situation can only really happen at a forecourt: anywhere else, your car got there by being driven. A brief spell of running, or just your ignition on. Your system has been primed, so petrol has left your tank and got to your filter and the fuel lines. Normally nothing more than emptying, flushing and sorting the fuel filter, and so still straightforward. Driven a couple of miles. Now your pump has spent these miles running on weakened fuel. The work is your tank, the lines, the fuel filter and fresh fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. A school run to Darrick Wood Junior School is one matter. A run as far as London, under 15 miles away, is a very different task. So is any mileage on the M25, under 5 miles from Locksbottom, where the motor has been labouring hard throughout. Driven on until it protested — clattering, smoke, a ragged idle, a dead throttle. The motor is telling you your fuel is no longer acting like diesel. Stop wherever you are — the verge on Park Avenue, a lay-by, a side street — and leave the car where it is. What goes first is still the drain and flush-through, and that takes care of it, with long-term damage very unusual if a vehicle is stopped quickly. ## Locksbottom motorists and the petrol in a diesel myths they hear 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 — that tank simply carries more of the same mixture. Percentage is not how a diesel fuel system copes with petrol, however much that advice assumes. If anything, the opposite holds. Myth: "A current diesel can cope with a bit of petrol." Smaller components and higher pressure are how a current diesel runs its fuel, and that makes the protection count more, not less. One myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it generally will not run, and so the driver stops — and the damage stops with them. Feed petrol to a diesel and it usually fires up, ticks over and pulls away like nothing happened — all the while its pump wears. Running doesn't mean fine. Myth: a two-stroke additive lets you to drive home. It was an old workaround, meant for another issue. It doesn't put back what petrol has weakened, and that petrol is still inside that tank later on. The next start sends petrol back round your pump from the lines and your filter, where some of that ends up once your engine has been run. That's 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 risky. ## How does petrol in a diesel happen? It's rarely carelessness, and nobody does it on purpose. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way. It happens when habit and the vehicle stop matching. Courtesy car, hire car, or a car that is brand new. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. Fuelling up in a hurry on the way to Orpington, with a train to catch. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. Throw in a back seat full of children, a phone call or rain, and habit wins. ## Locksbottom motorists: how to prevent petrol in a diesel next time - Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on each forecourt. The label is what counts. - Check the filler flap. Plenty of motors state the fuel inside the flap or on the cap. Look at it on the first fill in any vehicle you don't know. - Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a house has one of each. So mark it. - It seems silly and it works: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. - While you're thinking about something else, this is an easy mistake to make — so put your phone away. - Add-on devices exist for vehicles without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label. - The moment you realise, stop: less petrol in that tank makes a weaker blend. What to do next doesn't change, though — still do not crank it. ## Put petrol in a diesel in Locksbottom already? Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. Ask the staff to help you roll it away from the petrol pump if you're still at the forecourt, whether that's BP or somewhere else. What got in, about how much, and if it's run: tell us that when you call 0333 366 0103. Corrosion and deposits form the trouble with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Locksbottom page. ## Why one petrol in a diesel task around Locksbottom costs more than another A fair single price doesn't exist here: four scenarios, four separate tasks. The situation itself does most of the work of moving your cost. Where the vehicle is counts too, and whether a van can safely get to it, after the share of petrol to what your tank takes. What went in, how much, and whether it's run — three questions we ask before quoting, not after, for precisely that reason. Those replies change a range into a straight figure. ## About Locksbottom, briefly Locksbottom is a suburban area in southeastern Greater London, situated near the River Ravensbourne at an elevation of around 98 metres. Locksbottom lies approximately 12 miles from central London and is surrounded by other suburban areas such as Keston Mark, Farnborough, and Crofton. Locksbottom has a population of around 3334 people and is characterised by predominantly detached housing. ## Fuel drain cover across Greater London, Locksbottom included Keston Mark, Farnborough and Crofton are among the places around Locksbottom that the same vans work, answering petrol in diesel call-outs across Locksbottom's BR postcode area. You need not move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations we drain. ## Still at the petrol pump around Locksbottom? Then you're in the best spot there can be. Switched off it remains; then call.