--- title: Greysteel: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/greysteel-county-londonderry/ location: Greysteel county: County Londonderry latitude: 55.031670 longitude: -7.120560 service: AdBlue in a Diesel Tank updated: 2026-10-03 --- # Greysteel: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? If AdBlue is already in your diesel tank, stop reading for a moment: leave your motor and the ignition off and call 0333 366 0103. In Greysteel, finding it before your engine runs normally means a drain and a thorough flush where it stands. Here in advance? Then the rest explains how it comes about and how to stop it happening at all. ## AdBlue in a diesel motor, and its separate tank Diesel feeds the engine — but many newer diesels driven round Greysteel and Ballykelly carry a second liquid as well. The exhaust, not your engine, is where AdBlue ends up: dosed into the fumes to fresh them, from a separate tank. Each tank has its own filler. On a lot of motors the two sit side by side under the same flap; on others the AdBlue filler is in the boot or under the bonnet. Diesel goes in on every filling station call-out, week in, week out. Far less commonly, the AdBlue side is topped up — mostly from a bottle, by a person thinking about where it goes. That gap is where the mistake lives. ## How AdBlue in your diesel tank occurs in Greysteel Three things tend to come together, and carelessness is seldom one of them. The warning comes first. As AdBlue runs low the car tells you, and if it runs out completely, the car drops into limp mode. So the top-up is done in a hurry: on a driveway off Crown Street before work, or in the car park at the pub in the village on the way home. Then your car is strange. A hire car, a new car or a company car puts the fillers where your last one didn't, and your hand gets to for the cap it would have used on the old one. A spout-topped bottle finds no resistance at a diesel filler any more than at an AdBlue one. So the tip, after started, carries on. The same few seconds decide it, in the middle of Greysteel or out in Killywool. ## The AdBlue filler and the diesel filler: telling them apart Look at these first, on a forecourt around Greysteel or a driveway out in Maydown. A few seconds, that's all. - Position misleads; the cap doesn't. AdBlue ones tend to be blue or carry the name "AdBlue" — diesel caps normally don't. - The size. On many vehicles the AdBlue filler neck is the smaller of the two. - A label inside your fuel flap frequently shows which fuel goes where, on many vehicles. Look for it. - In your boot or under the bonnet: that is where the filler is if it's not by your diesel cap, and the handbook says which. - The person who drove the vehicle last. On a hire or company car picked up from somewhere like the car park outside the nearest station, ask before you leave, not when the light comes on. ## Keeping AdBlue out of the diesel tank when you top up Wherever around County Londonderry the light comes on, this is a routine for the day. - Not in a rush on the side of Crom Street, not on a slope, not with the motor running: park then switch off first. - Silly as it sounds, saying "AdBlue" aloud while you unscrew the cap does the trick — after you have located the filler and read it. - The diesel cap remains on. Where both share a flap, confirm it is closed before the bottle comes up. - Using the bottle's own spout, pour slowly — and stop when it is full or the bottle is empty. - Before you start your car, shut the cap and check a second time that the diesel cap was never opened off. Discover during the second or third step that the bottle went into the diesel filler? That is where you stop. Step five stays out. ## AdBlue in the diesel tank already, around Greysteel? The short order of things, starting with no starting your engine. Do not switch your ignition on; on many diesels that alone runs the fuel pump. AdBlue does not mix with diesel — it sinks to the bottom of your tank, where the fuel is sucked from — so do not top up with diesel to dilute it. On a forecourt — the nearest petrol station, another forecourt nearby or any other — the staff will normally help roll the car clear, if you ask. Leave it where it is if you're on your own driveway around Greysteel. If your engine has already run, stop as soon as it is safe then switch off. Leave the M77 — over 50 miles out of Greysteel — at the first exit. A short hop across Greysteel is a smaller job than a run towards Derry, under 10 miles away, and so tell us about how far it went. ## Our arrival in Greysteel, and what takes place next By the local primary school, near the centre or on your own drive: wherever your car has stopped, our engineers come to it. We ask what went in, roughly how much, and if it's run, because the answers settle the work and the price. No one heads out until you've heard our price over the phone. Then your tank is drained and the fuel system cleaned thoroughly. AdBlue crystallises and is corrosive to some of the metals in a fuel system, so it doesn't wash out on its own — which is why the flush matters more with AdBlue than with petrol. Filter flushed or, if needed, replaced; fresh diesel in; then a test of your vehicle. We do not leave until it has been started and is running properly. If the engine has not run, the majority of jobs take about half an hour once we're there, using pumps that are safe on a working forecourt and quiet enough to use outside a house at night. Nothing upfront; you settle up on the day. Afterwards, the VAT invoice and the report from the engineer are handed to you for your insurer. Before we get there, take a look at your policy; many carry cover for misfuelling. ## About Greysteel, briefly Greysteel is a coastal locality in County Londonderry, situated near the city of Derry and close to the villages of Killywool and Eglinton. Greysteel has a population of around 1131 people and is characterized by semi-detached housing. Greysteel sits at an elevation of 38 metres, overlooking the surrounding coastline. Greysteel is located approximately 7.8 miles from Derry and 377.6 miles from London. ## AdBlue drains around Greysteel, and County Londonderry beyond Greysteel is a coastal area, and our vans that cover it also work the towns near it, Eglinton and Glack among them, across the BT postcode area. The van reaches you fastest with a postcode starting BT47 3. The car stays put. Anywhere it sits — beside a street just off the centre, on a layby heading to the green space at the edge of the village, on a drive — that is where it gets cleared. If you are near a boundary, or somewhere hard to explain like the back of the far end of the built-up part, ring and ask rather than guessing. ## For Greysteel motorists, the short version Always, the cap; after that, the pour. Petrol in Diesel drains it where it stands, anywhere across County Londonderry, if AdBlue has gone in the diesel tank anyway — so leave it off then phone 0333 366 0103.