--- title: AdBlue in a Diesel Tank Catbrain: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/catbrain-gloucestershire/ location: Catbrain county: Gloucestershire latitude: 51.522400 longitude: -2.613010 service: AdBlue in a Diesel Tank updated: 2026-10-18 --- # AdBlue in a Diesel Tank in Catbrain: How It Occurs and How to Prevent It If AdBlue is already in your diesel tank, stop reading for a moment: leave the engine and your ignition off then ring 0333 366 0103. Caught before the motor runs, it is normally a drain and a thorough flush, done where your car is in Catbrain. If you are reading before it has happened, the rest of this page is about why it takes place and how to make sure it does not. ## AdBlue in a diesel motor, and its separate tank Many modern diesels on the roads about Catbrain and Easter Compton carry two liquids, not one. Diesel goes to the motor. AdBlue goes to your exhaust, where it is sprayed into the gas to clean it, and it lives in a tank of its own. There's a filler for each tank. On a lot of vehicles the two sit side by side under the same flap; on others the AdBlue filler is in the boot or under the bonnet. At the petrol pump, the diesel side is topped up all the time. Seldom topped up, AdBlue normally goes in from a bottle, poured by a driver who must stop and think what cap to use. The mistake grows in the gap between the two. ## AdBlue in the diesel tank around Catbrain: how it occurs Carelessness seldom causes it. Instead is three things lining up together. Hurry follows from the warning. The car warns you as AdBlue runs low, and a dry tank puts it into limp mode — so the top-up gets done in a rush, before work on a drive off Silveys Cottages, or heading home in the car park outside Redwood Farm. Next, your hand reaches for the cap it knew on the old motor — because a rental car, a new motor or a company car puts the fillers where your last one did not. Nothing halts the tip after it has started, because a bottle with a spout goes into a diesel filler as readily as an AdBlue one. The bottle fits. The same few seconds decide it, in the middle of Catbrain or out in Cribbs Causeway. ## The AdBlue filler and the diesel filler: telling them apart Before you tip anything, whether on a drive in Berwick or a forecourt around Catbrain, check these. They take a couple of seconds. - The cap. The AdBlue cap is frequently blue, or marked "AdBlue". The diesel cap normally isn't. Read it rather than going by position. - Look at the size: the smaller filler neck is, on plenty of vehicles, the AdBlue one. - A label inside the fuel flap often says which fuel goes where, on plenty of vehicles. Look for it. - In your boot or under the bonnet: that's where the filler sits if it is not by your diesel cap, and the handbook says which. - Ask the person who drove it last — before you leave, not when the light comes on — if you pick up a hire or company car from somewhere like the car park at Patchway. ## How to top up without AdBlue in your diesel tank The day the light goes on, wherever in Gloucestershire, follow this routine. - Park then switch off. Not on a slope, not with the motor running, and not in a rush on the side of Catbrain Lane. - Daft as it sounds, speaking "AdBlue" out loud while you unscrew the cap does the trick — once you have located your filler and read the cap. - Leave your diesel cap on. If both sit under one flap, check the diesel cap is still closed before you lift the bottle. - Finish when that tank fills or the bottle runs dry; until then, tip slowly using its built-in spout. - Only then, start your car: close the cap, check once more, and make sure the diesel cap was never opened. If at step two or three you find you have already poured into your diesel side, stop there. Step five stays off limits. ## Put AdBlue in the diesel tank around Catbrain already? Then the order of things is short. Do not start the engine. The fuel pump runs on many diesels the moment the ignition goes on — and so keep it off. Don't top up with diesel to dilute it: AdBlue does not mix with diesel, it sinks to the bottom of your tank, where the fuel is sucked from. Ask the staff to help roll the car clear of the pump if you are at a forecourt — the Andy's Gas, the Shell or somewhere else. If you are on your own driveway in Catbrain, leave the car where it stands. Already started? Pull over when it is safe, then switch off. Catbrain lies under a mile from the M5; on it, use the first exit. Distance matters — a quick hop across Catbrain is a smaller job than driving under 5 miles to Bristol — so say about how far it went. ## When our technicians arrive in Catbrain, what takes place? Outside Brentry Primary School, close to Vue or on your own driveway: wherever your car has stopped, our technicians come to it. Those answers determine the work and our quote, so our engineers ask what was put in, roughly how much, and if it has run. No one sets off until you've heard our price by phone. Next: draining, then a full flush of the entire system. AdBlue crystallises and is corrosive to some of the metals in a fuel system, so it does not wash out on its own — which is why the flush matters more with AdBlue than with petrol. The filter flushed or, where it must be, replaced; fresh diesel in; and then a test of your vehicle. We do not leave until it has been started and is running properly. Unstarted cars mostly mean a half-hour visit after arrival. The kit is fine on a busy forecourt, and hushed enough for a residential street after dark. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. Wrong-fuel cover is part of many insurance policies — so make use of the wait to look at yours. ## About Catbrain, for a moment Catbrain is a small suburban area in Gloucestershire, situated near the city of Bristol and the coastal areas of the South West region. Catbrain sits at an elevation of 57 metres, with detached housing being the predominant type of accommodation in the area. Catbrain is close to nearby places such as Cribbs Causeway, Compton Greenfield, and Brentry, and is located approximately 4.8 miles from Bristol. Catbrain has a population of around 730 residents. ## AdBlue drains across Gloucestershire, Catbrain included Compton Greenfield and Brentry are among the towns near Catbrain, a residential suburb, that the same vans cover, throughout BS postcodes. Quote a postcode that starts BS10 7, and our van gets there fastest. No need to shift the vehicle. Draining happens right there, whether a driveway, a road near Rhia Wyllie, or a lay-by on the way to Bristol Saracens RFC. Ring and ask rather than assuming if you're near a boundary, or somewhere hard to describe, like the back of The Venue. ## For Catbrain people, the short version Read the cap before you pour. Petrol in Diesel drains it on the spot, anywhere around Gloucestershire, if AdBlue has gone in your diesel tank anyway — and so leave the car off and phone 0333 366 0103.