--- title: Explained: AdBlue in a Diesel Tank Cassington canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/cassington-oxfordshire/ location: Cassington county: Oxfordshire latitude: 51.794920 longitude: -1.342480 service: AdBlue in a Diesel Tank updated: 2026-10-16 --- # Cassington: How Does AdBlue End Up in a Diesel Tank, and How Do You Prevent It? AdBlue already in your diesel tank? Then put this page down for now, keep your ignition and motor off, and call 0333 366 0103. A drain plus a thorough flush, carried out just where your car sits in Cassington, is usually what it takes when found before the engine runs. If you are reading before it has happened, the remainder 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 Diesel goes to your motor — yet many newer diesels driven around Cassington and Yarnton carry another fluid as well. Kept in a tank of its own, AdBlue is fed into your exhaust gas to clean it. Every tank comes with a filler of its own. Under one flap, side by side: that's the arrangement on many cars. Elsewhere, AdBlue's filler is beneath the bonnet or in your boot instead. Topping up your diesel side at the petrol pump happens constantly. The AdBlue side is filled far less often, usually from a bottle, and normally by somebody who has to stop and think where it goes. Mistakes happen in that gap between the two. ## AdBlue in the diesel tank around Cassington: how it takes place Rarely is it carelessness: normally three things line up. Haste comes from the warning. Your car tells you as AdBlue runs low, and an empty tank sends it into limp mode — so the top-up happens quickly, before work on a driveway off Yarnton Road, or on the way home in the car park at Red Lion. Then the vehicle 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. Nothing halts the tip once it has started, because a bottle with a spout goes into a diesel filler as readily as an AdBlue one. The bottle fits. It takes a few seconds, whether out in Worton or bang in the centre of Cassington. ## How to tell the AdBlue filler from the diesel one A couple of seconds is all these take — so run through them before you tip anything, on a drive in Wytham or a forecourt around Cassington. - Blue and marking: an AdBlue cap is regularly blue, or says "AdBlue", where a diesel cap normally does not. Trust the cap, not its position. - Look at the size: the smaller filler neck is, on many motors, the AdBlue one. - Look inside the fuel flap: plenty of vehicles have a label there showing which fuel goes where. - Cannot find it beside the diesel filler? Then check beneath the bonnet or inside your boot — the owner's manual will say where. - Collecting a hire or company car, say at the car park outside Hanborough? Ask the person who drove the vehicle last before you set off, not when the light goes on. ## Keeping AdBlue out of your diesel tank when you top up For the day the warning comes on — anywhere it is across Oxfordshire — a simple routine to use. - Park then switch off. Not on a slope, not with your motor running, and not in a rush on the side of The Green. - Say "AdBlue" out loud as you unscrew the cap, once you find the AdBlue filler and reading it. Silly, yes, but it does the trick. - If both sit under one flap, check your diesel cap is still closed before you lift the bottle — and leave the vehicle on. - Using the bottle's own spout, pour slowly — and stop when it is full or the bottle is empty. - Close the cap and check a second time. Make sure the diesel cap was never opened. Only then start the vehicle. Find during the second or third step that the bottle went in the wrong tank? That's where you stop. Stage five is out. ## Put AdBlue in the diesel tank in Cassington already? Then the order of things is short. Don't start the motor. Do not switch the ignition on; on plenty of diesels that alone runs the fuel pump. Filling up with diesel won't dilute it: instead, AdBlue sinks to the base of the tank, just where the fuel is taken from. If you're on a forecourt, whether it is the BP or the Esso, ask the staff to help roll your car away from the pump. At home in Cassington? So your car stays put. Already run? Pull over once it is safe, then switch off. Leave the M40 — under 10 miles out of Cassington — at the next junction. About how far did it go? Crossing Cassington is smaller a job than a trip of under 5 miles towards Oxford, and so tell us. ## Our arrival around Cassington, and what occurs next We come to the vehicle wherever it has stopped, whether that is outside St Peter's Church of England Primary School, Cassington, near Cassington Village Hall or on your own driveway. The answers settle the work and our price, and so we ask what got in, about how much, and if it has run. You hear that price on the phone, before anyone sets off. Then the tank is emptied and the system cleaned thoroughly. With AdBlue that counts more than with petrol: it crystallises and is corrosive to some of the metals in a fuel system, and so it doesn't wash out on its own. The fuel filter is cleaned, or replaced where it needs to be; fresh diesel goes in; and your car is tested. Before we go, we start the engine and check that it's running properly. Using pumps safe on a working forecourt and quiet enough for use outside a house at night, most jobs in which your motor hasn't run take about half an hour once we are there. Paying is on the day, not upfront, and you are given the documents your insurer wants: an engineer report and a VAT invoice. Before we get there, take a look at your insurance documents; plenty carry cover for misfuelling. ## About Cassington and where it is Cassington is a village in Oxfordshire, situated on the River Evenlode, with a mix of old and new buildings, including many detached houses. Cassington sits near the city of Oxford, approximately 4.7 miles to the west, and is surrounded by other villages such as Worton and Eynsham. Cassington has a population of around 793 people and is located at an elevation of 67 metres above sea level. Cassington is also within commuting distance of London, being around 55.7 miles to the west of the capital. ## AdBlue drains round Cassington, and Oxfordshire beyond Cassington is a village, and our vans that cover it also work the places near it, Swinford and Eynsham among them, across the OX postcode area. A postcode starting OX29 4 gets our van to you fastest. Shifting the car is not necessary. Anywhere it stands — near Saint Peter, in a layby en route to Cassington Recreation Ground, at home — that's where it gets emptied. Ring and ask rather than assuming if you're near a boundary, or somewhere hard to describe, like the back of The Linesmen. ## The short version for Cassington drivers Before you tip, read the cap. Still AdBlue in the diesel tank? Petrol in Diesel will drain it where it stands, wherever across Oxfordshire: switch the vehicle off then call 0333 366 0103.