--- title: Explained: AdBlue in a Diesel Tank Johnstone canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/johnstone-renfrewshire/ location: Johnstone county: Renfrewshire latitude: 55.836900 longitude: -4.513090 service: AdBlue in a Diesel Tank updated: 2026-10-02 --- # AdBlue in a Diesel Tank in Johnstone: Why It Occurs and How to Avoid It Keep your motor and ignition off and ring 0333 366 0103 now — the rest can wait if AdBlue is already in your diesel tank. A drain plus a full flush, carried out just where the vehicle stands around Johnstone, is usually what it takes when caught before your motor runs. Not happened yet? Below, the rest of the page covers the why it takes place and the ways to prevent it for good. ## AdBlue in a diesel vehicle: two tanks, two fillers Not one fluid but two: that's what many newer diesels near Johnstone and Linwood run, with diesel for your engine. Your exhaust, not the motor, is where AdBlue ends up: dosed into the fumes to fresh them, from a separate tank. Each tank has its own filler. Under one flap, next to each other: that's the arrangement on a lot of motors. On others, AdBlue's filler is under the bonnet or in the boot instead. Diesel goes in at each forecourt call-out, week in, week out. Far less regularly, the AdBlue side is topped up — normally from a bottle, by a person thinking about where it goes. The error lives in that gap. ## AdBlue in the diesel tank in Johnstone: how it takes place It is hardly ever carelessness. Three things tend to line up. First, the warning. Low AdBlue brings a warning from the car, and running out means limp mode — so a hurried top-up, perhaps before work off High Street, perhaps at The Silver Tassie on the way home that evening. Unfamiliar cars are next, too. Hire cars, new motors and company motors put their fillers in new places, and the hand goes for the cap 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, and so nothing stops the pour once it has started. It takes seconds, be it out in Quarrelton or bang in the centre of Johnstone. ## Which filler is for AdBlue, and which for diesel? Be it a Johnstone forecourt or a drive out in East Fulton, take a few seconds on these before anything goes in. - Check the cap instead of going by where it sits: AdBlue caps are often blue or marked "AdBlue", and diesel ones usually aren't. - Check the size: the smaller filler neck is, on plenty of cars, the AdBlue one. - A label inside the fuel flap frequently shows which fuel goes where, on many vehicles. Look for it. - In your boot or under the bonnet: that's where the filler sits if it's not by the 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 the nearest station. ## Topping up AdBlue without it reaching your diesel tank Anywhere in Renfrewshire the light comes on, this is a routine for the day. - Not in a rush on the side of Collier Street, not on a slope, not with the engine running: park and switch off first. - Say "AdBlue" out loud as you unscrew the cap, once finding the AdBlue filler and reading it. Daft, perhaps, yet it does the trick. - Both behind a single flap? Then make sure the lid on your diesel filler is still closed ahead of raising the bottle. - Gently is best, through the bottle's own spout, until it's full or the bottle runs out. - Close the cap and check a second time. Make sure the diesel cap was never opened. Only then start your car. If at step two or three you find you have already poured into your diesel side, stop there. Never go on to stage five. ## Put AdBlue in your diesel tank around Johnstone already? The short order of things, beginning with no starting your motor. On many diesels your ignition alone runs the fuel pump, and so do not switch the car on. Don't top up with diesel to thin it: AdBlue doesn't mix with diesel, it sinks to the bottom of the tank, where the fuel is sucked from. The staff at Morrisons, Esso or any forecourt will usually help to push the car away when asked. Leave it where it is if you are on your own drive around Johnstone. Stop as soon as it is safe then switch off, if your motor has already run. The next junction means the place to leave if you're on the M8, under 3 miles from Johnstone. Mileage matters — a short hop across Johnstone is a smaller job than driving under 15 miles to Glasgow — so say roughly how far it went. ## Our arrival in Johnstone, and what happens next Wherever the car came to rest, be it outside the local primary school, near War Memorial or on your own drive, our van travels to it. What fluid went in, the quantity, and if it ran: our engineers ask because those answers decide the work and price. That quote is given on the call, ahead of any van leaving. The system is then purged thoroughly, after the tank is emptied. More than with petrol, it matters with AdBlue: crystals build up, certain metals are attacked, and none of that washes away on its own, however long it is left. Filter flushed or, if needed, swapped; fresh diesel in; then a check of your vehicle. Before we go, we start the engine and check that it's running smoothly. Most jobs are finished in roughly half an hour once we arrive, as long as your motor has not run — and the pumps our technicians use are fine on a live forecourt and quiet after dark outside a house. You pay on the day, with nothing upfront, and get a VAT invoice and an engineer report for your insurer. Many insurance policies include misfuelling cover, and so it's worth checking yours whilst we are on the way. ## About Johnstone itself Johnstone is a town situated in a riverside setting within Renfrewshire, in the western part of Scotland's central low-lying area. It is part of a larger historic county that shares its name. The town's location in this region provides a unique character. Johnstone is nestled in a scenic area near a river. ## AdBlue drains around Johnstone and across Renfrewshire Johnstone is a riverside town, and our teams that cover it also work the towns around it, Cartside and Howwood Road among them, across the PA postcode area. Fastest of all: quote a PA5 8 postcode for our van. The vehicle doesn't need to move. A drive, a lay-by on the way to Rankine Park, a side street near Johnstone Town Hall: our engineers drain the vehicle where it stands. Assuming won't help at the back of Johnstone Library, close to a border, or anywhere hard to pin down; phone and check. ## The short version for Johnstone motorists Tip no AdBlue till you have read the cap. If AdBlue has gone in your diesel tank all the same, leave the car off and ring 0333 366 0103. Petrol in Diesel clears it where it stands, anywhere across Renfrewshire.