--- title: Petrol in a Diesel Car Colindale — Explained canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/colindale-greater-london/ location: Colindale county: Greater London latitude: 51.595690 longitude: -0.248840 service: Petrol in a Diesel Car updated: 2026-10-08 --- # How Worried Should You Be? Petrol in a Diesel Car in Colindale If it has not been started, worry far less than you probably are. Everyone in Colindale starts with "have I ruined it?", and the honest answer is normally no: petrol left in your tank of a diesel stays harmless until priming, cranking or driving draws it into the system. Petrol in Diesel is who to phone, with your motor left off, and so it stays that way. What petrol really does to a diesel, how to judge how far it's gone, and how to stop it from happening a second time: that's the remainder of this page. ## Your engine and petrol in a diesel: what happens Two tasks fall to diesel on its route through a motor. It combusts, and before it combusts it lubricates. The high-pressure pump and the injectors are made to very fine tolerances, and the diesel passing through them is what stops those surfaces from wearing down against one another. Petrol does the first task badly and the second not at all. A pump running on a petrol mix is wearing itself out, because petrol is thinner than diesel and takes away the protection the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any clattering comes. Together, those leave the shape of the issue plain. Contact does not do the damage — movement does. A tank with petrol in it is a fuel issue. Once your pump has been working on that petrol, a mechanical fault has started: whatever is shed by a pump that's wearing down is carried onward to the injectors with your fuel. ## Colindale, petrol in a diesel: four situations, from mild to significant Fuelled but not once started — the best it gets. Only your tank has petrol in it, so the job is clearing that tank and cleaning your system where your car sits. This scenario can only really occur on a forecourt: anywhere else, the car got there by being driven. The ignition switched on, or a short start. The system has been primed, and so petrol has left that tank and reached your filter and the lines. Drain, flush, see to the filter: still usually easy. Your pump has spent a couple of miles on diluted fuel — that is what driving the car meant. Tank, lines, filter, then clean fuel put through the whole circuit: that's this work, and the way the vehicle was driven matters as much as the mileage. Driving the kids to Beis Yaakov Primary School is one kind of trip. Very different again: a run to Westminster, under 10 miles away, or any miles on the M1, under a mile from Colindale, where the engine never stopped running hard. Driven until it complained. Clattering, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your engine signalling fuel that no longer acts like diesel. Whether it's the verge on Pasteur Close, a lay-by or a side street, stop where you are then leave it. The fuel drain and flush still go first, and they sort it out: if a vehicle is stopped early, long-term damage is very rare. ## What Colindale drivers get told about petrol in a diesel — and the myths in it "Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. That advice assumes a diesel fuel system handles petrol by percentage. It does not. "Current diesels can handle a little petrol" — a myth, and nearer the opposite. Protection matters more on newer diesels, not less, because their fuel passes through finer parts at higher pressure. "It starts, it drives, and so there is no harm" — the myth that catches more drivers than any other. A petrol engine fed diesel usually will not run, and so the motorist stops and the damage stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump grinds. Being able to run isn't the same as being fine. "A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate issue. What petrol has weakened stays thinned, and the petrol stays in that tank anyway. Myth: "Drain the tank yourself and you are sorted." Once the motor has been run, some of that petrol is no longer in your tank: it is in your filter and the fuel lines, and it goes straight back through the pump at the next start. And, a can of petrol filled by the kerbside is truly dangerous. ## How it happens: petrol in a diesel Nobody does it on purpose, and it's seldom carelessness. 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 car at all. The forecourt makes it simple, and the slip runs one way. When routine and the vehicle stop matching, it takes place. Courtesy car, hire car, or a motor that's brand new. Two motors on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A hurried fill on the way to Hendon with a train to catch. Precisely the moment it occurs: after years of driving petrol, someone fills a diesel Volkswagen Tiguan for the first time. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done. ## How to avoid petrol in a diesel at your next fill-up around Colindale - The label is what counts, so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt. - The first fill in an unfamiliar car is the time to check the filler flap — on it, or on the cap, plenty of vehicles state the fuel to use. - Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key if a home has one of each. So mark it. - Before the nozzle comes off the pump the first time you fuel a hired or new motor, say "diesel" out loud. Daft, yes, yet it works. - Put your phone away. This is an easy mistake to make whilst you are thinking about something else. - Some diesels come with a filler built to block a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump. - The moment you notice, stop: less petrol inside your tank means a thinner mixture. What to do next doesn't change, though — still do not crank it. ## Colindale: already put petrol in a diesel? The order of things is short, then. Don't switch the ignition on, and do not fire it up. Ask the attendants to help you roll it away from the petrol pump if you're still on the forecourt, whether that is Shell or anywhere else. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it's run. AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different fault — Colindale has a page all for it. ## Colindale petrol in a diesel tasks: why one costs more than another Four separate jobs sit behind the four scenarios above — which is why there is no fair single quote. What moves the cost is mostly which of them you're in. The proportion counts next, meaning how much of the tank is petrol, followed by the position of your car and whether getting to it is safe for a van. Ahead of any quote, not after, come three questions: your fuel that got in, the quantity, and whether it has run. That's why. The replies change a range into a straight figure. ## About Colindale, for a moment Colindale is a suburban area in northwest London, situated near the River Brent and the Welsh Harp reservoir. Colindale sits at an elevation of around 48 metres, approximately 8 miles from central London. Colindale is characterised by its predominantly flat-type housing and is surrounded by other suburban areas, including Grahame Park and The Hyde. Colindale has a population of around 20,665 residents. ## Across Greater London and in Colindale: fuel drain cover Petrol in diesel calls around Colindale — part of the NW postcode area — go to teams that likewise cover the places round it, Grahame Park, The Hyde and Burnt Oak included. We drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us. ## Still at the pump in Colindale? Then you're in the best place there can be. Keep the car turned off, and ring.