--- title: AdBlue in a Diesel Tank Pentre-dwr: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/pentre-dwr-swansea/ location: Pentre-dwr county: Swansea latitude: 51.652100 longitude: -3.887760 service: AdBlue in a Diesel Tank updated: 2026-10-12 --- # Preventing AdBlue in a Diesel Tank in Pentre-dwr: Why It Occurs AdBlue already in the diesel tank? Then set this page down for now, leave the ignition and engine off, then call 0333 366 0103. A drain plus a full flush, carried out right where your car sits around Pentre-dwr, is usually all it takes when caught before your motor runs. If you're reading before it has happened, the rest of this page is about why it occurs and how to make sure it does not. ## AdBlue in a diesel vehicle: two tanks, two fillers Not one liquid but two: that is how many modern diesels near Pentre-dwr and Llwynbrwydrau carry, with diesel for your motor. Your exhaust, not the motor, is where AdBlue ends up: dosed into the fumes to fresh it, from its own tank. There is a filler for every tank. Many of cars share a single flap for both, whereas some move the AdBlue filler to your boot or under the bonnet. At the petrol pump, the diesel side is topped up all the time. Far less commonly, the AdBlue side gets filled — normally from a bottle, by someone working out where it goes. The mistake grows in that gap between them. ## How AdBlue in your diesel tank takes place around Pentre-dwr It is rarely carelessness. Three things tend to line up. On a drive off Maes-lan before work, or in the car park at The Halfway on the way home: that is where the hurried top-up takes place. Why the rush? As AdBlue runs low the vehicle warns you, and if it is gone, limp mode follows. The old car's cap is where your hand reaches — yet a hire car, a new car or a company car keeps the fillers somewhere else. That's the second factor: a new motor. And the bottle fits. A bottle with a spout goes into a diesel filler as easily as an AdBlue one, and so nothing stops the tip after it has started. Trallwn or the middle of Pentre-dwr: it takes the same few seconds either way. ## How to tell the AdBlue filler from the diesel one Before you pour anything, whether on a drive in Peniel Green or a forecourt in Pentre-dwr, check these. They take a couple of seconds. - Check the cap instead of going by where it sits: AdBlue ones are regularly blue or marked "AdBlue", and diesel caps normally are not. - On many motors, the size tells: AdBlue has the smaller filler neck. - Look inside your fuel flap: plenty of motors carry a label there saying which fuel goes where. - The handbook. If the filler is not by your diesel cap, it is in the boot or under the bonnet, and the handbook says which. - Whoever had it before knows. Ask as you collect a hire car or company car — from Llansamlet's car park, say — rather than once the warning comes on. ## Keeping AdBlue out of the diesel tank when you top up A routine for the day the light comes on, wherever around Swansea that is. - Turn off after you park — level ground, motor stopped, and not in a rush beside Rhyd y Felin 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. - If both sit under one flap, check your diesel cap is still closed before you lift the bottle — then leave the car on. - Finish once the tank fills or the bottle runs dry; before that, pour gently through its own spout. - Before starting the car, shut the cap and look again that the diesel cap never opened off. If at step two or three you find you have already poured into your diesel side, stop there. Stage five stays out. ## Already put AdBlue in your diesel tank in Pentre-dwr? Brief order, then. First: your engine stays off. The fuel pump starts on plenty of diesels as soon as the ignition goes on — and so leave it off. AdBlue does not mix with diesel — it sinks to the bottom of your tank, where your fuel is drawn from — so do not top up with diesel to dilute it. If you are on a forecourt, whether it's the Texaco or the Tesco, ask the staff to help push your car away from the pump. On your own drive around Pentre-dwr? Then the vehicle stays put. Where your engine has run by now, stop somewhere safe and switch the car off. Pentre-dwr lies under a mile from the M4; there, use the next exit. About how far did it go? Hopping across Pentre-dwr is less work than a trip of under 5 miles towards Swansea, and so say. ## Pentre-dwr: what happens when our technicians turn up Our van reaches the car anywhere it has come to rest — your own drive, near Bethel Chapel, or by the local primary school. Those replies decide the work and our quote, and so our technicians ask what went in, about how much, and if it has run. You hear that quote on the phone, before anyone heads out. Next: draining, then a thorough flush of the whole system. 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 here than with petrol. The fuel filter is flushed, or replaced where it needs to be; clean diesel goes in; and the car is tested. Your engine is fired up next and checked to make sure it runs smoothly, all before our engineers leave. Most jobs are finished in about half an hour after we get there, as long as the motor hasn't run — and the pumps we use are fine on a live forecourt yet quiet at night beside a house. Paying is on the day, not upfront, and you receive the documents your insurer asks for: an engineer report and a VAT invoice. While we travel, take a look at your policy; plenty carry cover for misfuelling. ## About Pentre-dwr Pentre-dwr is a locality situated near the coast in Swansea, with an elevation of around 68 metres above sea level. Pentre-dwr lies close to the city of Swansea, approximately 3.2 miles away, and is surrounded by other nearby places such as Trallwn, Winsh-wen, and Tair-ysgol. Pentre-dwr has a population of around 1780 people and predominantly consists of semi-detached housing. ## AdBlue drains around Pentre-dwr and across Swansea Winsh-wen and Tair-ysgol are among the places near Pentre-dwr, a coastal area, that the same teams cover, throughout SA postcodes. Give a postcode that starts SA7 9, and our van arrives quickest. Moving the vehicle isn't necessary. A driveway, a lay-by on the way to Primrose Park, a side street close to Peniel Green Church: we drain the vehicle where it stands. Tricky to explain, like the back of Guru Nanak Sikh Community Centre? Close to a county line? Checking is better than guessing, so ring. ## In short, for Pentre-dwr drivers First, the cap; after that, the tip. If AdBlue has gone in the diesel tank all the same, leave the vehicle off and call 0333 366 0103. Petrol in Diesel empties it where it sits, anywhere in Swansea.