--- title: Explained: Petrol in a Diesel Car Highgate canonical: https://www.petrolinadieselcar.co.uk/petrol-in-diesel/highgate-east-sussex/ location: Highgate county: East Sussex latitude: 51.090310 longitude: 0.033780 service: Petrol in a Diesel Car updated: 2026-10-07 --- # Should You Worry? Petrol in a Diesel Car in Highgate If it hasn't been started, you can worry less than you probably are. Till the ignition primes the pump, the starter turns, or your car is driven, petrol in a diesel tank just sits there and does no harm. Which means the truthful reply to that first Highgate query — "have I wrecked it?" — usually no. Leave your engine off then ring Petrol in Diesel — that keeps it like that. The rest of this page covers 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. ## Inside the engine: what petrol in a diesel really does Passing through an engine, diesel is doing two jobs at once. It lubricates to begin with, and only then does it burn. The high-pressure fuel pump and the fuel injectors are built to very fine gaps, and the diesel passing through them is what keeps those surfaces from wearing down against one another. Poorly at the first, not at all at the second: that's petrol. It is thinner than diesel and strips away the lubrication the system depends on, so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from. Taken together, they show what shape the trouble has. Not contact but circulation is what does the damage. A tank with petrol in it is a fuel problem. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on. ## Highgate, petrol in a diesel: four cases, from mild to major Fuelled, and never started: no case is better. Only that tank has petrol in it, so the job is clearing that tank and purging your system where the car stands. This situation can only really happen on a forecourt: anywhere else, your car got there by being driven. Your ignition switched on, or a short start. Petrol has come out of that tank and got to the filter and the fuel lines, since your system has been bled. Drain, flush, deal with the filter: still usually simple. Driven a couple of miles. Now your pump has spent these miles labouring on thinned fuel. How hard the vehicle was driven counts as much as how far, and the work takes in the tank, your lines, the filter and clean fuel through the entire system. Short trips, such as the school run to Forest Row Church of England Primary School and Nursery, are one thing. A run as far as Brighton and Hove, under 25 miles away, is a very different job. So is any mileage on the M23, under 10 miles from Highgate, where the engine has been running hard throughout. Driven on till it protested — rattling, smoke, an uneven idle, a soft throttle. The motor is telling you your fuel is no longer acting like diesel. Stop where you are — on the verge on Inkpen Lane, at the kerb, down a side road — and do not move it again. A vehicle pulled over soon very seldom has permanent damage, as the fuel drain and the flush, which still come first, take care of it. ## Petrol in a diesel stories Highgate people hear "Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. A bigger tank of the same mixture is all you get, because topping up removes nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes. If anything, the opposite is true. Myth: "A current diesel can cope with a bit of petrol." A modern diesel runs its fuel through smaller parts at higher pressure, which makes the protection count more, not less. This is the one that fools motorists. Myth: "If it starts and drives, there is no damage done." The driver of a petrol motor fed diesel usually stops, because it will not run, and the harm stops there. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, while your pump grinds. Fine and running aren't the same thing. Myth: "Add some two-stroke oil and drive the car home." It's an outdated workaround for a different problem. None of what petrol weakened is put back by it — and later, your tank still holds that petrol. Once your engine has been run, part of the petrol sits in the filter and the lines, not your tank — and your next start sends it straight back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. Draining petrol into a can at the kerbside is also really dangerous. ## How does petrol in a diesel occur? It's rarely carelessness, and nobody does it on purpose. One way only, because of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol vehicle. That is how the forecourt makes it straightforward. It happens when routine and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. A forecourt you know, but with its pumps laid out differently. A hurried fill on the way to East Grinstead 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. The hand does what it has always done when you add rain, a phone call or a back seat full of children. ## Next time you fill up in Highgate: avoiding petrol in a diesel - 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, but not on each forecourt. - Check your filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on the first fill in any vehicle you don't know. - Label the key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember. - It seems daft and it works: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. - Put the phone away. This is an easy mistake to make whilst you are thinking about something else. - Up to a point, a misfuel inhibitor helps: some diesels have a filler built to reject a petrol nozzle, and aftermarket devices are available for the remainder. Treat it as a backstop, then keep checking the pump. - As soon as you realise, stop: less petrol in your tank makes a weaker mixture. What to do next does not change, though — still do not fire it up. ## Put petrol in a diesel around Highgate already? In that case, there is only a short order of things. Starting it is out, and so is turning on your ignition. If you're still at the forecourt — Tesco or anywhere else — ask the staff to help you push the car clear of the pump. Then phone 0333 366 0103 and tell us what went in, roughly how much, and if it has run. AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Highgate has a page all for it. ## Why one petrol in a diesel task around Highgate costs more than another Four different tasks lie behind the four situations above — which is why there is no fair single price. Chiefly, your cost moves 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. Before any quote, not after, we ask three questions: the fuel that went in, the quantity, and if it's run. That's why. Given those replies, you get a straight figure instead of a range. ## About Highgate Highgate is a suburban area in East Sussex, situated inland at an elevation of 82 metres, and is located near Tompsets Bank and Forest Row. Highgate is characterized by its predominantly detached housing stock, reflecting the area's residential nature. Highgate sits within the wider South East region, approximately 20 miles from Brighton and Hove and 29.7 miles from London. Highgate remains a small, quiet community with a population of around 1999 residents. ## Fuel drain cover around Highgate and across East Sussex Our vans answering petrol in diesel calls around Highgate, in the RH postcode area, equally work the spots around it, Tompsets Bank, Forest Row and Quabrook included. A forecourt, a supermarket car park, a lay-by or your own drive are all places our engineers drain, and the vehicle doesn't need to come to us. ## At the pump around Highgate, right now? The best spot there is, then — that's where you are. Leave it switched off, and ring.