--- title: Foxhole: AdBlue in a Diesel Tank, Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/foxhole-swansea/ location: Foxhole county: Swansea latitude: 51.628440 longitude: -3.930270 service: AdBlue in a Diesel Tank updated: 2026-10-14 --- # AdBlue in a Diesel Tank in Foxhole: How It Occurs and How to Prevent It If AdBlue is already in your diesel tank, stop reading for a moment: leave your motor and your ignition off then ring 0333 366 0103. In Foxhole, finding it before your motor turns usually leaves a drain and a full flush on the spot. Here before the event? In that case what follows explains how it happens and what to stop it happening at all. ## Two fillers, two tanks: AdBlue in a diesel car Plenty of current diesels on the roads around Foxhole and Swansea carry two liquids, not one. Diesel goes to the engine. AdBlue's own tank keeps it, and from there it is sent to your exhaust, and there a spray treats the fumes. 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 your boot or under the bonnet. The diesel side is filled at the pump all the time. The AdBlue side is fuelled far less regularly, usually from a bottle, and normally by someone who has to stop and think where it goes. The mistake grows in that gap between them. ## How does AdBlue in the diesel tank take place around Foxhole? Carelessness rarely causes it. Instead is three things lining up at once. The warning comes first. As AdBlue runs low the vehicle 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 Deepglade Close before work, or in the car park outside The Ship on the way home. Unfamiliar motors are second, as well. Hire cars, new vehicles and company motors place their fillers in new places, and the hand goes for the cap it used on the old one. And the bottle fits. A bottle with a spout goes into a diesel filler as easily as an AdBlue one, so nothing stops the tip after it has started. The same few seconds decide it, in the middle of Foxhole or out in St Thomas. ## Which filler is for AdBlue, and which for diesel? A couple of seconds is all the checks take — so run through them before you pour anything, on a drive in Pentre-chwyth or a forecourt in Foxhole. - Read the cap instead of going by where it sits: AdBlue ones are frequently blue or marked "AdBlue", and diesel ones usually are not. - Look at the size: the smaller neck is, on many motors, the AdBlue one. - The flap. Look inside the fuel flap for a label. Plenty of motors say there which fuel goes where. - The handbook. If the filler isn't by the diesel cap, it is in the boot or under the bonnet, and the handbook says which. - Collecting a hire or company car, say at the car park outside Swansea? Ask the person who drove it last before leaving, rather than when the light goes on. ## How to top up without AdBlue in the diesel tank On the day the light comes on — wherever you are across Swansea — a simple routine to use. - Park and switch off. Not on a slope, not with your engine running, and not in a rush on the side of Jericho Road. - Say "AdBlue" out loud as you unscrew the cap, after finding the AdBlue filler and reading it. Daft, perhaps, yet it works. - The diesel cap stays on. When the two share a flap, confirm it's closed before the bottle comes up. - Stop when your tank fills or the bottle runs dry; until then, tip slowly through its built-in spout. - Before starting your car, shut the cap and look again that your diesel cap never came off. Stop there if you find, at stage two or three, that you have already poured into your diesel side. Don't go on to stage five. ## AdBlue in your diesel tank already, in Foxhole? Do not start your motor: that is how the short order of things starts. Keep the ignition off too, because on many diesels it alone runs your pump. Do not top up with diesel to thin it: AdBlue does not mix with diesel, it sinks to the bottom of the tank, where the fuel is sucked from. On a forecourt — Sainsbury's, Burrows Service Station or any other — the staff will usually help roll your car clear, if you ask. Leave it where it is if you're on your own drive in Foxhole. Stop as soon as it is safe then switch off, if your motor has already run. Leave the M4 — under 5 miles out of Foxhole — at the next junction. Tell us about how far it went: a run towards Swansea, under a mile away, is a bigger job than a short hop across Foxhole. ## What takes place when we arrive in Foxhole Our van comes to the car wherever it stopped — your own driveway, beside Saint Thomas Community Centre, or by the local primary school. We ask what was put in, roughly how much, and if it has run, since the answers decide the work and our price. No one sets off before you've heard our price over the phone. The fuel system is then cleaned thoroughly, once your tank is drained. Not like petrol, AdBlue forms crystals and eats at some fuel-system metals, and neither clears away by itself. That is why it matters more. Your filter is flushed, or replaced where it needs to be; clean diesel goes in; and the vehicle is tested. We do not leave until it has been fired up and is running correctly. Unrun vehicles mostly mean a half-hour job after arrival. The kit is safe on a busy forecourt, and hushed enough for a driveway late at night. The insurer usually wants an engineer's report and the VAT invoice, and you get both at the end. Payment comes on the day, with no deposit. Wrong-fuel cover is included in many insurance policies — so use the wait to look at yours. ## About Foxhole Foxhole is a suburban area in Swansea, situated near the coast and approximately 0.7 miles from the city centre. Foxhole sits at an elevation of around 57 metres, with terraced housing being the predominant type of accommodation in the area. Foxhole is close to nearby places such as St Thomas, Hafod, and Dan-y-graig, and is part of the wider Swansea urban area. ## AdBlue drains round Foxhole, and Swansea beyond Being a residential suburb, Foxhole shares its vans nearby places — Hafod, Dan-y-graig — all the way across SA postcodes and the wider area beyond. Give a postcode that starts SA1 8, and the van gets there quickest. The car remains put. Wherever it stands — beside St Thomas Library, on a layby heading to Kilvey Community Woodland, at home — that is where it is emptied. Awkward to pin down, like the back of Bethesda Chapel? Close to a border? Checking is better than assuming, so phone. ## Foxhole drivers: the short version Before you pour, read the cap. Even so AdBlue in your diesel tank? Petrol in Diesel can empty it where it is, wherever in Swansea: switch it off and call 0333 366 0103.