--- title: Explained: AdBlue in a Diesel Tank Cadoxton canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/cadoxton-the-vale-of-glamorgan/ location: Cadoxton county: The Vale of Glamorgan latitude: 51.413630 longitude: -3.257140 service: AdBlue in a Diesel Tank updated: 2026-10-25 --- # Why It Occurs and How to Avoid It: AdBlue in a Diesel Tank in Cadoxton Stop here a minute when your diesel tank already holds AdBlue in it: ignition off, engine off, then ring 0333 366 0103. Caught before the engine runs, it is normally a drain and a thorough flush, done where the car is in Cadoxton. The rest of this page covers why it occurs and how to ensure it doesn't — handy if you are reading ahead of time. ## AdBlue in a diesel vehicle: two tanks, two fillers No single liquid but two: that's what many newer diesels around Cadoxton and Barry Dock carry, with diesel feeding your motor. The exhaust, not your motor, is where AdBlue ends up: dosed into the gas to fresh it, from its own tank. Every tank has a filler of its own. On a lot of vehicles 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 forecourt visit, again and again. Far less often, the AdBlue side gets filled — normally from a bottle, by someone working out where it goes. It is in the gap that the mistake lives. ## Cadoxton: how AdBlue in the diesel tank takes place Rarely is it carelessness: normally three things coincide. To start with, the warning. Low AdBlue brings a message from your car, and running dry leads to limp mode — so a rushed top-up, maybe before work off Barry Road, or outside King William IV on the way home after work. Then the car is strange. A hire car, a new vehicle 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. Lastly, the bottle fits: diesel filler or AdBlue one, it goes in as easily, and once the pour begins, no part halts it. It's seconds, be it in Gibbonsdown or right in the heart of Cadoxton. ## The AdBlue filler and the diesel filler: telling them apart Check these before pouring, at a forecourt in Cadoxton or a drive out in Barry. Seconds, that's all. - The cap. The AdBlue cap is frequently blue, or marked "AdBlue". The diesel cap usually isn't. Read it rather than going by position. - The size. On many vehicles the AdBlue filler neck is the smaller of the two. - A label inside your fuel flap often shows which fuel goes where, on many vehicles. Look for it. - The handbook says where it is when your filler isn't next to the diesel cap: your boot, or under the bonnet. - The person who drove the car 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 Wherever in The Vale of Glamorgan the light comes on, this is a routine for the day. - Park then switch off. Not on a slope, not with your motor running, and not in a rush on the side of Court Road. - Daft as it sounds, speaking "AdBlue" out loud as you unscrew the cap does the trick — after you've found the filler and read it. - If both sit under one flap, check the diesel cap is still closed before you lift the bottle — and leave the car on. - Using the bottle's own spout, tip slowly — and stop when it is full or the bottle is empty. - Close the cap, and check once more — making sure the diesel cap remained closed the whole time. Only then, start your car. Find at the second or third step that the bottle went into the wrong filler? That's where you stop. Step five stays off limits. ## Put AdBlue in your diesel tank around Cadoxton already? Then the order of things is short. Don't start your engine. On many diesels the ignition alone runs the fuel pump, so don't switch the vehicle on. Filling up with diesel will not thin it: rather than mixing, AdBlue drops to the bottom of the tank, right where the fuel is taken from. At a forecourt — Texaco, Morrisons or another — the staff will normally help push your car away, when you ask. Leave it where it is if you are on your own driveway around Cadoxton. When your engine has been run by now, stop safely then switch the vehicle off. On the M4, under 10 miles from Cadoxton, that means the next junction. A short hop across Cadoxton is a smaller job than a run towards Cardiff, under 10 miles away, so tell us roughly how far it went. ## When our technicians turn up in Cadoxton, what takes place? Our engineers come to the car wherever it has stopped, whether that is outside the local primary school, close to Hope Church or on your own drive. Both the work and our price rest on three answers — what fluid, which quantity, and if it has run — so we ask. The quote comes over the phone, before any van leaves. Your system is then cleaned thoroughly, once that tank is emptied. AdBlue crystallises and is corrosive to some of the metals in a fuel system, and so it does not wash out on its own — which is why that matters more here than with petrol. Testing is last: before that, fresh diesel goes in, and your filter is flushed or replaced as needed. We don't leave until it has been fired up and is running correctly. Using pumps fine on a working forecourt and quiet enough to use outside a house at night, most jobs in which your motor hasn't run need about half an hour once our technicians arrive. Nothing upfront; you settle up that day. Afterwards, the VAT invoice and the report from the engineer are handed to you for the insurer. Misfuelling cover is part of many insurance policies — so make use of the wait to check yours. ## About Cadoxton, briefly Cadoxton is a suburban area in the Vale of Glamorgan, situated on the coast of Wales, with a mix of terraced housing and local amenities. Cadoxton sits at an elevation of 38 metres, looking out towards the Bristol Channel, and is located near the communities of Gibbonsdown and Palmerstown. Cadoxton is close to the city of Cardiff, which is approximately 5.7 miles away, and is part of the wider Cardiff urban area. Cadoxton has a population of around 9619 people, living in a variety of predominantly terraced homes. ## AdBlue drains round Cadoxton, and The Vale of Glamorgan beyond Cadoxton is a residential suburb, and the vans that cover it also work the towns around it, Palmerstown and Merthyr Dyfan among them, across the CF postcode area. Fastest of all: quote a CF63 1 postcode for the van. Moving the vehicle isn't necessary. Wherever it stands — near St Cadoc's (Church in Wales), on a lay-by heading to Victoria Gardens, on a drive — that's where it gets drained. Tricky to pin down, like the back of Jenner Park? By a county line? Asking beats guessing, and so phone. ## The short version for Cadoxton motorists Tip no AdBlue until you've read the cap. Even so AdBlue in the diesel tank? Petrol in Diesel can empty it where it stands, anywhere in The Vale of Glamorgan: switch the vehicle off then ring 0333 366 0103.