--- title: Big Mancot: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/big-mancot-flintshire/ location: Big Mancot county: Flintshire latitude: 53.195220 longitude: -3.021750 service: AdBlue in a Diesel Tank updated: 2026-10-08 --- # AdBlue in a Diesel Tank in Big Mancot: Why It Happens and How to Prevent It Leave the motor and ignition off then phone 0333 366 0103 now — reading can wait when AdBlue is already in your diesel tank. In Big Mancot, catching it before the motor turns usually leaves a drain and a full flush where it stands. If you are reading before it has happened, the rest of this page is about why it occurs and how to make sure it doesn't. ## AdBlue in a diesel car: two tanks, two fillers Many newer diesels on the roads round Big Mancot and Pentre carry two liquids, not one. Diesel goes to the motor. Stored in a tank of its own, AdBlue is fed into your exhaust gas and cleans it. Each tank has its own filler. Many of cars have a single flap for the two, while some put the AdBlue filler to your boot or under the bonnet. At the petrol pump, the diesel side gets filled all the time. Someone who has to stop and work out where it goes usually tops up the AdBlue side, from a bottle, and far less commonly. The error lives in that gap. ## AdBlue in the diesel tank around Big Mancot: how it occurs Carelessness rarely causes it. What does is three things lining up at once. On a driveway off The Paddock before work, or in the car park at The White Bear heading home: that's where the hurried top-up takes place. Why the rush? As AdBlue runs low the car tells you, and if it is empty, limp mode kicks in. Unfamiliar cars come second, too. Rentals, new motors and company vehicles place their fillers differently, and habit reaches for the cap it used on the old one. Lastly, the spout fits: diesel filler or AdBlue filler, it goes in just as readily, and once the tip begins, no part halts it. Little Mancot or the middle of Big Mancot: it takes the same few seconds either way. ## The AdBlue filler and the diesel filler: telling them apart Be it a Big Mancot forecourt or a drive out in Hawarden, spend a couple of seconds on these before anything goes in. - Check the cap instead of going by position: AdBlue caps are often blue or marked "AdBlue", and diesel ones normally aren't. - Plenty of cars fit AdBlue the smaller filler of the two. - A label inside your fuel flap often says which fuel goes where, on many cars. Look for it. - The handbook shows which it lives when the filler is not next to the diesel cap: the boot, or under the bonnet. - The person who drove it last. On a hire or company car picked up from somewhere like the car park at Hawarden, ask before you leave, not when the light comes on. ## How to top up without AdBlue in the diesel tank When the light comes on, anywhere in Flintshire, follow this routine. - Pull in on level, motor off, with time to spare — not hurried on the side of Wilton Road. - Find the AdBlue filler, check the cap, and speak the name "AdBlue" out loud as you unscrew it. It sounds daft. It does the trick. - Leave the diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift the bottle. - Finish once your tank is topped up or the bottle is empty; before that, tip slowly through the built-in spout. - Before starting the vehicle, close the cap and look a second time that the diesel cap was never came off. If at step two or three you find you have already poured into the diesel side, stop there. Don't go on to stage five. ## AdBlue in the diesel tank already, around Big Mancot? The short order of things, starting with not starting your motor. The fuel pump starts on many diesels as soon as the ignition goes on — so keep it off. Topping up with diesel won't weaken it: rather than mixing, AdBlue sinks to the bottom of that tank, just where fuel is drawn from. Ask the attendants to help push your car away from the petrol pump if you're at a forecourt — the Asda, the Esso or somewhere else. Your own driveway in Big Mancot is the place it stays. Already run? Stop once it is sensible, then turn off. Big Mancot sits under 5 miles from the M56; on it, use the first exit. About how far did it go? Hopping across Big Mancot is smaller a job than a run of under 10 miles towards Chester, so tell us. ## Our arrival in Big Mancot, and what takes place next Wherever the car has stopped, whether outside Saughall All Saints Church of England Primary School, near Mancot Village Hall or on your own drive, our van travels to it. What fluid was put in, the amount, and whether it ran: our engineers ask because the replies set both work and quote. No one heads out until you have had our quote by phone. Next: a drain, then a full flush of the entire system. Unlike petrol, AdBlue leaves crystals and eats at some fuel-system metals, and neither washes out unaided. That is why it counts more. The filter is cleaned, or replaced where it needs to be; fresh diesel goes in; and the car is tested. Your engine is started next and checked to be sure it runs properly, all before our technicians head off. Unstarted cars mostly mean a half-hour job after the moment we arrive. The kit is safe on a live forecourt, and hushed enough for a residential street late at night. No money in advance; you settle up on the day. At the end, the VAT invoice and a report from the engineer are handed to you for the insurer. Wrong-fuel cover is included in many insurance policies — and so use the wait to check yours. ## About Big Mancot, briefly Big Mancot is a village in Flintshire, situated inland at an elevation of 23 metres, and is located near the English border. Big Mancot lies close to the city of Chester, which is approximately 5 miles away, and is part of a wider area that includes nearby Little Mancot and Mancot Royal. Big Mancot has a population of around 1872 people, who mostly reside in semi-detached houses. Big Mancot is also near The Moor, a local area of interest. ## Big Mancot and Flintshire: AdBlue drains across the area Mancot Royal and The Moor are among the places near Big Mancot, a rural village, that the same teams cover, over CH postcodes. Fastest of all: give a CH5 2 postcode to the van. Your car doesn't need to shift. A driveway, a lay-by on the way to Willow Park, a side street near Mancot Community Library: our engineers drain the vehicle where it stands. Guessing doesn't help behind Greenacres Animal Park, close to a border, or somewhere awkward to describe; ring and ask. ## Big Mancot people: the short version Pour nothing until you've read the cap. If AdBlue has gone in your diesel tank all the same, leave the car off then call 0333 366 0103. Petrol in Diesel drains it where it stands, anywhere around Flintshire.