--- title: Explained: Petrol in a Diesel Car Greenwich canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/greenwich-greater-london/ location: Greenwich county: Greater London latitude: 51.478690 longitude: -0.010820 service: Petrol in a Diesel Car updated: 2026-10-16 --- # Greenwich: Petrol in a Diesel Car? How Worried to Be Probably less than you are now — provided no one has started it. "Have I ruined it?" is the first thing everyone around Greenwich asks, and the truthful answer is usually no, because petrol resting in a diesel tank hurts nothing till it is dragged through the system — by ignition priming, by your starter, or by driving. To leave the vehicle like that, call Petrol in Diesel and leave your engine alone. What petrol really does to a diesel, how to judge how far it has gone, and how to stop it from happening a second time: that is the remainder of this page. ## Petrol in a diesel: what does it do to your engine? On its way through a motor, diesel has two tasks. Lubricating comes before burning; it does both. What keeps the surfaces inside the high-pressure pump and the injectors from grinding against each other is your diesel passing through them — they are built to very fine clearances. Of those two tasks, petrol manages the first badly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on that mixture to wear itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the rattling. Together, those make the shape of the issue plain. Contact doesn't do the harm — circulation does. Where that petrol is only inside your tank, it's a fault of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors further on. ## Four situations we see in Greenwich: how bad is petrol in a diesel? Fuelled, and not started: nothing beats it. The petrol is inside your tank and only that tank, and the job is a drain and a flush where your car sits. This is the one situation that can only truly occur at a forecourt, as anywhere else the vehicle has been driven to get there. Your ignition switched on, or a brief start. Petrol has come out of that tank and got to the filter and the lines, because the system has been primed. Drain, flush, deal with the filter: still usually simple. Those few miles driven meant your pump labouring on fuel diluted by petrol the whole way. Tank, lines, filter, then clean fuel put through the whole circuit: that's the work, and the way the vehicle was driven matters as much as the mileage. Driving the children to James Wolfe Primary School and Centre for the Deaf is one sort of trip. Getting as far as London, under 5 miles away, makes a very different job — as does any mileage on the M11, under 10 miles from Greenwich, with your engine running hard the whole time. Driven till it protested. Rattling, an uneven idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel has stopped acting like diesel. Stop wherever you are — the verge on Royal Hill, a lay-by, a side street — then leave the car where it is. A vehicle stopped early very rarely has long-term damage, as the fuel drain and the flush, which still go first, deal with it. ## Myths Greenwich people hear about petrol in a diesel Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up takes out nothing; it gives you a bigger tank of the same mixture. That advice assumes a diesel fuel system tolerates petrol by percentage. It does not. "Newer diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through finer components: that is how a newer diesel moves its fuel, and so the lubrication matters more, not less. Myth: "If it starts and drives, there's no damage done." This is the one that catches drivers. Diesel in a petrol motor normally means a motor that will not run: the motorist stops, and so does the damage. While the pump grinds, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Running doesn't mean fine. An outdated workaround for a distinct issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened gets put back by it — and later, the tank still contains the petrol. "Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in the filter and lines, ready to go right back through your pump at the next start. Draining petrol into a can at the roadside is also truly dangerous. ## Petrol in a diesel: how does it take place? On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol motor at all. So the mistake runs one way. When routine and the car stop matching, it occurs. Courtesy car, hire car, or a motor that is brand new. Two vehicles on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. A train to catch, and a hurried fill on the way to the nearest station. Years of petrol motors behind you, a diesel Renault Clio in front of you at the forecourt for its first tank — that's when. With rain, a call arriving, or children to deal with, your hand just does what it always has. ## Greenwich people: how to avoid petrol in a diesel next time - The label is what counts, and so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt. - Many motors state the fuel type inside the filler flap or on the cap, so check there on the first fill in any car you don't know. - One of each in the household? Label the key to the diesel — a bright fob, a sticker — since intending to remember is not enough. - "Diesel", aloud, before you pick up the nozzle — every time a new or hired car gets its first tank. It sounds silly. It does the trick. - Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the petrol pump. - Some diesels come with a filler designed to reject 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 reading the petrol pump. - The moment you notice, stop: less petrol inside that tank means a weaker mixture. What to do next does not change, though — still do not start the car. ## Already put petrol in a diesel in Greenwich? The order of things is brief, then. Do not switch the ignition on, and don't fire it up. Ask the attendants to help you push it away from the petrol pump if you're still at the forecourt, whether that is Valero or anywhere else. Then ring 0333 366 0103 and tell us what went in, roughly how much, and whether it has run. Corrosion and deposits form the issue with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own Greenwich page. ## One petrol in a diesel task in Greenwich costs more than another. Why? Four different tasks lie behind the four scenarios above — which is why there is no fair single quote. The scenario itself does most of the work of moving your cost. After that it is the proportion — how much petrol got in against how much the tank takes — and after that where your car is and whether our van can reach it safely. What went in, how much, and whether it's run — three questions our engineers ask before quoting, not after, for exactly that reason. The replies turn a range into a straight figure. ## About Greenwich itself Greenwich is a locality in south-east London, situated on the south bank of the River Thames at an elevation of around 11 metres. Greenwich sits adjacent to nearby places such as Maze Hill, Deptford, and St Johns, and is located approximately 5.4 miles from central London. Greenwich is predominantly composed of flat housing, accommodating a population of around 9320 residents. Greenwich offers a mix of old and new buildings, reflecting its long history as a riverside settlement. ## Fuel drain cover across Greater London, Greenwich included Petrol in diesel calls in Greenwich — part of the SE postcode area — go to teams that likewise cover the locations about it, Maze Hill, Deptford and St Johns among them. Our engineers drain where the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us. ## In Greenwich and still at the petrol pump? The best place there is, then — that's where you are. Ring, and leave it turned off.