--- title: Explained: Petrol in a Diesel Car Somerley canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/somerley-west-sussex/ location: Somerley county: West Sussex latitude: 50.778560 longitude: -0.843530 service: Petrol in a Diesel Car updated: 2026-10-07 --- # How Worried Should You Be? Petrol in a Diesel Car in Somerley Unstarted? Then less anxious than you likely are. Until the ignition primes your pump, your starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does no harm. Which makes the honest reply to the first Somerley question — "have I wrecked it?" — normally no. Leave the motor off and phone Petrol in Diesel — that keeps it that way. The remainder of this page explains 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 again. ## The motor and petrol in a diesel: what goes on On its way through an engine, diesel does two tasks. It burns, and before it burns it protects. The high-pressure fuel pump and your injectors are built to very fine gaps, and the diesel passing through them is what keeps those surfaces from wearing down against each other. The second job petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on the mixture wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the rattling. The shape of the trouble is plain once you put those together. It is circulation that does the damage, not contact. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, borne by the fuel, into the injectors further along, which is why a pump that has been working on the petrol is where a mechanical problem starts. ## Somerley, petrol in a diesel: four situations, from mild to serious Fuelled, and never started: nothing beats it. Being on a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol held inside that tank alone, it is drained and flushed on the spot, and nothing more is needed. A brief spell of running, or just the ignition on. With the system primed, your lines and filter already contain petrol that came from the tank. Usually nothing more than draining, rinsing and seeing to your filter, so still straightforward. Those few miles driven were your pump running on fuel weakened by petrol the whole way. The work is your tank, your lines, the fuel filter and fresh fuel through the entire system, and how hard the car was driven counts as much as how far. A school run to Birdham CE Primary School is one thing. A run as far as Chichester, under 5 miles away, is a very different task. So is any miles on the Waterlooville Bypass, under 10 miles from Somerley, where the motor has been labouring hard throughout. It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone uneven. That's your engine telling you its fuel has stopped acting like diesel. Stop wherever you are — the verge on Bookers Lane, a lay-by, a side street — then leave the vehicle where it is. A vehicle stopped soon very seldom has permanent damage, since the drain and the flush, which still come first, deal with it. ## Somerley motorists and that petrol in a diesel myths they hear It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up removes nothing; it gives you a bigger tank of the same mix. A diesel fuel system does not accept petrol by percentage in the way that advice presumes. Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. Smaller components and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication matter more, not less. The myth that catches motorists out: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it generally will not run, so the motorist stops — and the damage stops with them. While the pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Fine and running are not the same at all. Myth: "Add some two-stroke oil and drive the car home." It's an outdated workaround for a different problem. It doesn't put back what petrol has diluted, and the petrol is still inside the tank later. The next start sends petrol back round your pump from the fuel lines and the filter, where some of that sits once the engine has run. That's why a DIY tank drain does not sort it — a myth. Clearing petrol into a can by the kerbside is also genuinely dangerous. ## Petrol in a diesel: how does it happen? On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the mistake runs one way. Habit and the vehicle getting out of step is when it happens. A vehicle that is new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. The pumps in a different order on a familiar forecourt. Filling up in a hurry en route to Fishbourne, with a train to catch. The first fill-up in a diesel Volkswagen Tiguan after years of driving petrol is precisely the moment it happens. Throw in rain, a phone call or a back seat full of kids, and the hand does what it has always done. ## Somerley people: how to prevent petrol in a diesel next time - Read the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what matters. - The first fill in an unfamiliar motor is the time to check the filler flap — on it, or on the cap, plenty of vehicles state which fuel they take. - A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, for a house with one of each. - It sounds daft and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. - Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away. - A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for cars without one. They are a backstop, not a reason to stop reading the petrol pump. - Less petrol means a thinner mix, so stop the moment you realise — though remembering that the next step is unchanged. It's still not to crank it. ## Petrol already in a diesel around Somerley? Begin here The order of things is brief, then. Don't crank it, and do not turn the ignition on. The attendants at the forecourt — whether at Shell itself or wherever you filled up — will normally help push it away from the pump if you ask. Ring 0333 366 0103 next, with three answers — the fuel, the approximate amount, and if it has run. If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits and not lost lubrication — and it has its own page for Somerley. ## One petrol in a diesel task around Somerley costs more than another. Why? The four situations above are four separate jobs, so no single quote for this would be honest. Mostly, your cost moves with which one you are in. The ratio counts next, meaning how much of that tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a van. What got in, how much, and whether it's run — three queries our engineers ask before pricing, not after, for precisely that reason. The answers turn a range into a straight figure. ## About Somerley, briefly Somerley is a small coastal village in West Sussex, situated near the cities of Chichester and the surrounding villages of Almodington, Earnley, and Birdham. Somerley sits at a low elevation of around 5 metres, close to the English Channel. Somerley has a population of approximately 511 residents, with a predominance of detached housing. Somerley is located within commuting distance of London, at around 59 miles away. ## Across West Sussex and around Somerley: fuel drain cover Almodington, Earnley and Birdham are among the locations around Somerley that the same teams work, answering petrol in diesel jobs across Somerley's PO postcode area. We drain wherever your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us. ## Still at the pump in Somerley? No position is better: that's where you are. Leave it turned off, then ring.