--- title: Explained: AdBlue in a Diesel Tank Scredda canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/scredda-cornwall/ location: Scredda county: Cornwall latitude: 50.356780 longitude: -4.785750 service: AdBlue in a Diesel Tank updated: 2026-10-03 --- # Avoiding AdBlue in a Diesel Tank in Scredda: Why It Happens If AdBlue is already in your diesel tank, stop reading for a moment: leave your engine and the ignition off then call 0333 366 0103. Normally, when the engine has not turned, it's drained and fully rinsed where the car sits around Scredda. 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 vehicle, and its separate tank Many modern diesels around Ruddlemoor, as well as Scredda, carry on two fluids; the motor gets just your diesel. Your exhaust, not your motor, is where AdBlue ends up: dosed into the fumes to fresh it, from a separate tank. 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 the boot or under the bonnet. The diesel side is fuelled at the petrol pump all the time. Someone who has to stop and think where it goes usually fills the AdBlue side, from a bottle, and much less regularly. The mistake grows in the gap between them. ## Scredda: how AdBlue in your diesel tank occurs It is seldom carelessness. Three things tend to line up. The warning comes first. As AdBlue runs low the vehicle tells you, and if it runs out completely, the vehicle drops into limp mode. So the top-up is done in a hurry: on a drive off Drummer's Hill before work, or in the car park at The Carclaze on the way home. Then your car is new. A hire car, a new vehicle or a company car puts the fillers where your last one did not, and your hand gets to for the cap it would have 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 once it has started. Whether it takes place in Carclaze or the middle of Scredda, it is the same few seconds. ## Telling the AdBlue filler from your diesel filler Check these first, on a forecourt in Scredda or a driveway out in Penhale. Seconds, that's all. - Check the cap instead of going by where it sits: AdBlue ones are often blue or marked "AdBlue", and diesel ones usually aren't. - On many vehicles, size gives it away: AdBlue gets the smaller filler neck. - Check inside the fuel flap: many vehicles carry a label there showing 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. - Ask the person who drove it last — before you leave, not when the light comes on — when you pick up a hire or company car from somewhere like the car park outside St Austell. ## Keeping AdBlue out of the diesel tank when you top up Wherever in Cornwall the light comes on, here is a routine for that day. - Park then switch off. Not on a slope, not with the motor running, and not in a rush on the side of Kaolin Heights. - Find the AdBlue filler, read the cap, and say the word "AdBlue" out loud as you unscrew it. It seems silly. It does the trick. - If both sit under one flap, check your diesel cap is still closed before you lift the bottle — and leave it on. - Slowly is best, through the bottle's own spout, until it's full or the bottle is empty. - Close the cap, then look again — confirm your diesel filler remained shut throughout. Only then, start the car. If at stage two or three you find you have already poured into your diesel side, stop there. Leave out stage five altogether. ## Scredda: already put AdBlue in the diesel tank? Do not start your motor: that is how the short order of things begins. The fuel pump runs on plenty of diesels the moment your ignition goes on — and so keep it off. Do not top up with diesel to dilute it: AdBlue does not mix with diesel, it sinks to the bottom of the tank, where the fuel is sucked from. If you're on a forecourt, whether it's the the nearest petrol station or the Asda, ask the staff to help push the car clear of the petrol pump. Your own driveway in Scredda is the place it should stay. If the motor has already run, stop as soon as it is safe then switch off. Come off the M5 — over 50 miles out of Scredda — at the first exit. Tell us roughly how far it went: a run towards Truro, under 15 miles away, is a bigger job than a short hop across Scredda. ## When our engineers turn up in Scredda, what happens? Anywhere the car came to rest, whether by Carclaze Community Primary School, beside Carclaze Methodist Church or on your own drive, our van comes to it. Both the work and the price rest on three answers — which liquid, which quantity, and whether it has run — so we ask. The quote comes on the call, before any van leaves. After that: draining, then a thorough flush of the entire system. Much more than with petrol, it counts with AdBlue: crystals build up, certain metals are attacked, and nothing washes out unaided, however long it sits. A test comes last: before that, clean diesel goes in, and the fuel filter is flushed or changed if necessary. Before we go, we start it and make sure that it's running properly. Most jobs are done in roughly half an hour after our technicians get there, as long as the engine has not run — and the pumps our technicians use are safe on a live forecourt yet quiet at night beside a house. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. It is worth checking your insurance while we travel to you: misfuelling cover is included with many policies. ## About Scredda and where it is Scredda is a small coastal hamlet in Cornwall, situated near the towns of Carclaze and Trethowel, with semi-detached housing being the predominant type of accommodation. Scredda sits at an elevation of 192 metres, overlooking the surrounding countryside and coastline. Scredda is located approximately 13 miles from Truro, the nearest city, and is part of the wider South West region of England. Scredda remains a quiet residential community with a population of around 658 people. ## AdBlue drains around Scredda, and Cornwall beyond Trethowel and Carluddon are among the towns near Scredda, a rural hamlet, that the same teams cover, throughout PL postcodes. Quickest of all: quote a PL25 5 postcode for the van. The car does not need to move. A driveway, a lay-by on the way to Polwarth Close Open Space, a side street close to Seymour Gospel Hall: we drain the vehicle where it sits. Tricky to pin down, like the back of Christian Meeting Hall Place? Close to a county line? Checking beats guessing, so phone. ## In short, for Scredda motorists First, the cap; then, the tip. AdBlue in the diesel tank after all? Keep it off and call 0333 366 0103; Petrol in Diesel drains it on the spot, across Cornwall.