--- title: Explained: AdBlue in a Diesel Tank Rhuddlan canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/rhuddlan-denbighshire/ location: Rhuddlan county: Denbighshire latitude: 53.291100 longitude: -3.466520 service: AdBlue in a Diesel Tank updated: 2026-10-11 --- # AdBlue in a Diesel Tank in Rhuddlan: Why It Occurs and How to Avoid It Leave your engine and ignition off then ring 0333 366 0103 first — reading can wait if AdBlue is already in your diesel tank. Caught before the engine runs, it is generally a drain and a thorough flush, done where your car is around Rhuddlan. Reading before the event? In that case what follows covers how it comes about and what to prevent it ever happening. ## Two fillers, two tanks: AdBlue in a diesel motor Plenty of newer diesels on the roads round Rhuddlan and Bodelwyddan carry two liquids, not one. Diesel goes to your motor. Its own tank keeps it, and from there it goes to the exhaust, and there a spray treats the gas. Separate tanks, separate fillers. On a lot of cars the two sit side by side under the same flap; on others the AdBlue filler is in the boot or under the bonnet. The diesel side is filled at the petrol pump all the time. Much less often, the AdBlue side gets topped up — mostly from a bottle, by a person working out where it goes. The mistake grows in the gap between them. ## How AdBlue in your diesel tank occurs in Rhuddlan Rarely is it carelessness: usually three things coincide. The warning comes first. As AdBlue runs low your car tells you, and if it runs out altogether, your vehicle drops into limp mode. So the top-up is done in a hurry: on a driveway off Gwindy Street before work, or in the car park outside New Inn Hotel on the way home. Then, the hand reaches for the cap it knew on the old car — because a hire car, a new car or a company car puts the fillers where your last one didn't. A spout-topped bottle meets no obstacle at a diesel filler any more than at an AdBlue one. And so the tip, once begun, keeps on. Pengwern or the heart of Rhuddlan: it takes the same few seconds in both. ## Telling the AdBlue filler from the diesel filler A couple of seconds is all the checks take — so check them before you pour anything, on a driveway in Dyserth or a forecourt in Rhuddlan. - Where it sits can mislead; the cap doesn't. AdBlue caps are often blue or bear the name "AdBlue" — diesel caps usually do not. - Many cars fit AdBlue the smaller filler of the two. - Look inside your fuel flap: plenty of cars have a label there showing which fuel goes where. - The handbook. If the filler is not by your diesel cap, it is in your boot or under the bonnet, 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 Rhyl, ask before you leave, not when the light comes on. ## Keeping AdBlue out of your diesel tank when you top up Wherever in Denbighshire the light comes on, this is a routine for the day. - Stop somewhere level, engine off, with time to spare — never hurried on the side of Parliament Street. - Say "AdBlue" out loud as you unscrew the cap, after you find the AdBlue filler and reading it. Daft, yes, yet it works. - If both sit under one flap, check the diesel cap is still closed before you lift the bottle — then leave the car on. - Finish once the tank is topped up or the bottle is empty; until then, tip gently using its built-in spout. - Shut the cap, and check again — making sure the diesel cap remained shut the whole time. Only then, start the vehicle. Stop there if you find, at step two or three, that you've already poured into your diesel side. Step five is off limits. ## Already put AdBlue in the diesel tank around Rhuddlan? The short order of things, starting with no starting the engine. The fuel pump starts on many diesels the moment the ignition goes on — so keep it off. AdBlue doesn't mix with diesel — it sinks to the bottom of the tank, where your fuel is sucked from — so do not top up with diesel to dilute it. At a forecourt — Texaco, Sainsbury's or another — the staff will usually help push the vehicle away, if you ask. Leave it where it is if you are on your own driveway around Rhuddlan. Already started? Stop once it is sensible, then turn off. The next junction is the place to leave if you are on the Moreton Spur, under 25 miles from Rhuddlan. A short hop across Rhuddlan is a smaller job than a run towards St Asaph, under 3 miles away, and so tell us roughly how far it went. ## When our technicians get there around Rhuddlan, what happens? Our engineers come to your car wherever it has stopped, whether that's outside the local primary school, close to Cylch Meithrin Rhuddlan or on your own drive. Both the work and our price depend on three answers — what fluid, which amount, and whether it's run — so our engineers ask. No one heads out before you've heard our price by phone. The system is then purged thoroughly, after your tank is cleared. Much more than with petrol, it counts with AdBlue: the crystals form, some metals are attacked, and nothing clears out on its own, however long it sits. Your filter is cleaned, or replaced where it needs to be; clean diesel goes in; and your car is tested. Before we go, our engineers start the engine and make sure that it's running smoothly. Using pumps safe on a working forecourt and quiet enough for use outside a house at night, most jobs in which your engine hasn't run need roughly half an hour once we are there. Payment happens on the day, not upfront, and you receive the documents an insurer asks for: an engineer report and a VAT invoice. Before we get there, have a look at your insurance documents; many include cover for misfuelling. ## About Rhuddlan itself Rhuddlan is a coastal town in Denbighshire, situated near the mouth of the River Clwyd, with a population of around 3791 people. Rhuddlan sits at a low elevation of 18 metres, close to the nearby city of St Asaph and the smaller communities of Pengwern and Ochr-y-foel. Rhuddlan is characterized by its predominantly detached housing stock, reflecting its role as a residential centre in the region. Rhuddlan is located approximately 187 miles from London, making it a relatively distant but still accessible town in north Wales. ## AdBlue drains across Denbighshire, Rhuddlan included As a coastal town, Rhuddlan shares its vans nearby areas — Ochr-y-foel, The Roe — all the way through LL postcodes and the surrounding area beyond. A postcode starting LL18 2 gets the van to you fastest. The vehicle remains put. Wherever it stands — beside St Mary's Parish Church, in a layby en route to Admiral's Recreation Ground, at home — that's where it gets cleared. Ring and ask rather than assuming if you are close to a border, or somewhere hard to explain, like the back of Rhuddlan Library. ## For Rhuddlan motorists, the short version Read the cap before you pour. Even so AdBlue in your diesel tank? Petrol in Diesel can drain it wherever it is, anywhere across Denbighshire: switch the car off and phone 0333 366 0103.