--- title: AdBlue in a Diesel Tank Culmore: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/culmore-county-londonderry/ location: Culmore county: County Londonderry latitude: 55.050000 longitude: -7.267000 service: AdBlue in a Diesel Tank updated: 2026-10-06 --- # Culmore: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? Keep the engine and ignition off then phone 0333 366 0103 first — reading can wait if AdBlue is already in your diesel tank. A drain plus a full flush, done right where your vehicle sits in Culmore, is usually all it takes if found before the motor runs. Not happened yet? Further down, the page covers the why it occurs and the how to avoid it altogether. ## AdBlue in a diesel motor: two tanks, two fillers Diesel goes to the engine — but plenty of current diesels driven around Culmore and Derry carry another fluid too. Kept in a tank of its own, AdBlue is fed into your exhaust gas and cleans it. There's a filler on each tank. Some motors put the AdBlue filler in your boot or under the bonnet; a lot of others place the two side by side under one flap. The diesel side is fuelled at the pump all the time. The AdBlue side is filled far less often, usually from a bottle, and normally by a person who has to stop and think where it goes. The slip lives in that gap. ## Culmore: how AdBlue in your diesel tank takes place Rarely is it carelessness: normally three things line up. First, the warning. Low AdBlue brings a warning from your car, and letting it run dry means limp mode — so a rushed top-up, maybe before work off Crom Street, perhaps at the pub in the village on the way home that evening. Then the car is strange. A hire car, a new car or a company car puts the fillers where your last one did not, and your hand gets to for the cap it would have used on the old one. And the bottle fits. A bottle with a spout goes into a diesel filler as easily as an AdBlue one, so nothing stops the tip after it has started. The same few seconds decide it, in the middle of Culmore or out in Strathfoyle. ## How to tell the AdBlue filler from the diesel one Be it a Culmore forecourt or a driveway out in Lettershendoney, take a few seconds on these before any goes in. - Colour and lettering: an AdBlue cap is often blue, or says "AdBlue", where a diesel cap usually doesn't. Go by the cap, not where it sits. - On plenty of cars, the size gives it away: AdBlue has the smaller filler neck. - The flap. Look inside the fuel flap for a label. Plenty of vehicles say there which fuel goes where. - The handbook says where it is if the filler isn't next to the diesel cap: the boot, or under the bonnet. - The person who drove it last. On a hire or company car collected from somewhere like the car park outside the nearest station, ask before you leave, not when the light comes on. ## Topping up AdBlue without it reaching your diesel tank On the day the light appears — anywhere you are in County Londonderry — a simple routine to follow. - Switch off after you park — flat ground, motor stopped, and never in a rush beside Rock Street at the roadside. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds daft and it does the trick. - Both under one flap? So make sure the lid on the diesel filler is still closed ahead of raising the bottle. - Stop when that tank is topped up or the bottle runs dry; until then, tip gently using its own spout. - Before starting the vehicle, close the cap and check a second time that the diesel cap never came off. Discover during the second or third step that the bottle went into the diesel tank? That's where you stop. Don't go on to stage five. ## Put AdBlue in your diesel tank in Culmore already? Then the order of things is short. Don't start your engine. Keep your ignition off too, because on plenty of diesels switching it on alone starts the pump. Topping up with diesel will not weaken it: rather than mixing, AdBlue sinks to the base of that tank, just where the fuel is drawn from. The staff at the nearest petrol station, another forecourt nearby or another forecourt will usually lend a hand pushing the car clear if asked. Your own drive in Culmore is the place it should stay. Already run? Stop once it's sensible, then turn off. On the M77, over 50 miles from Culmore, that means the next junction. About how far did it go? Hopping across Culmore is smaller a job than a trip of under 5 miles towards Derry, and so tell us. ## Our arrival around Culmore, and what takes place next We come to the car wherever it has stopped, whether that is outside the local primary school, close to the centre or on your own drive. Which liquid was put in, the quantity, and whether it ran: our engineers ask since the replies set the work and price. You get that price on the phone, before anyone sets off. The system is then cleaned thoroughly, once the tank is drained. Unlike petrol, AdBlue forms crystals and eats at certain fuel-system metals, and none of that clears out unaided. Hence it counts more. Filter cleaned or, where needed, swapped; fresh diesel in; then a test of the vehicle. Before leaving, our technicians fire it up and check that it's running properly. If the motor has not run, most jobs take about half an hour once we are there, using pumps that are safe on a busy forecourt and quiet enough to use outside a house at night. Payment happens on the day, not upfront, and you are given the paperwork an insurer wants: an engineer report and a VAT invoice. Plenty of insurance policies include misfuelling cover, so it's worth checking yours whilst we are on the way. ## About Culmore, briefly Culmore is a small coastal locality in County Londonderry, situated near the city of Derry and close to the mouth of the River Foyle. Culmore is characterized by its low-lying terrain, with an average elevation of just 4 metres above sea level. Culmore has a mix of housing types, but detached homes are the most common, and it is located near other localities such as Strathfoyle and Eglinton. ## Culmore and County Londonderry: AdBlue drains across the area Over BT postcodes, the vans covering Culmore — a coastal area — work the surrounding spots too, Eglinton and Maydown included. Quickest of all: give a BT48 8 postcode for the van. Shifting the vehicle is not necessary. A drive, a lay-by on the way to the green space at the edge of the village, a side street close to a street just off the centre: our engineers drain it where it stands. Tricky to pin down, like the back of the far end of the built-up part? Close to a border? Checking beats guessing, and so ring. ## Culmore drivers: the short version Always, the cap; after that, the tip. If AdBlue has gone in your diesel tank regardless, leave it off then call 0333 366 0103. Petrol in Diesel clears it where it stands, anywhere in County Londonderry.