--- title: AdBlue in a Diesel Tank Tregolls: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/tregolls-cornwall/ location: Tregolls county: Cornwall latitude: 50.185120 longitude: -5.174190 service: AdBlue in a Diesel Tank updated: 2026-10-21 --- # Avoiding AdBlue in a Diesel Tank in Tregolls: Why It Happens Stop here for a moment when your diesel tank already holds AdBlue in it: ignition off, engine off, and ring 0333 366 0103. A drain and a thorough flush, done right where the vehicle sits in Tregolls, is normally what it needs if caught before your engine runs. Nothing happened yet? Further down, the rest of the page explains the reasons it occurs and the ways to prevent it altogether. ## Two fillers, two tanks: AdBlue in a diesel motor Not one liquid but two: that is how plenty of newer diesels near Tregolls and Tresevern Croft run, with diesel feeding your motor. Kept in a tank of its own, AdBlue is sprayed into the exhaust gas to clean it. Every tank has a filler of its own. Many of cars have a single flap for the two, whereas others move the AdBlue filler to your boot or under the bonnet. Topping up your diesel side at the pump goes on constantly. Someone who has to stop and work out where it goes normally fills the AdBlue side, from a bottle, and much less frequently. That gap is where the mistake lives. ## Tregolls: how AdBlue in your diesel tank occurs Three things tend to line up, and carelessness is seldom one of them. On a driveway off South Road before work, or in the car park at Seven Stars Inn on the way home: that's where the rushed top-up takes place. Why the rush? As AdBlue runs low your car warns you, and if it is empty, limp mode follows. New-to-you motors come second, as well. Hire cars, new cars and company cars put their fillers differently, and the hand goes for the cap used on the old one. A spouted bottle finds no resistance at a diesel filler any more than at an AdBlue one. And so the pour, after begun, keeps on. The same few seconds settle it, in the middle of Tregolls or out in Stithians. ## The AdBlue filler and the diesel filler: telling them apart Whether a Tregolls forecourt or a driveway out in Herniss, take a couple of seconds on these before any is poured in. - Check the cap instead of going by position: AdBlue ones are frequently blue or marked "AdBlue", and diesel ones usually are not. - Look at the size: the smaller neck is, on many vehicles, the AdBlue one. - Open the filler flap and check for a label — plenty of cars show what belongs in which filler right there. - The handbook shows where it is if the filler isn't next to your diesel cap: the boot, or under the bonnet. - Whoever had it before knows. Ask as you pick up a hire car or fleet car — at Penryn's car park, perhaps — not when the light comes on. ## Keeping AdBlue out of your diesel tank when you top up A routine for the day the light comes on, wherever across Cornwall that is. - Park and switch off. Not on a slope, not with the motor running, and not in a rush on the side of Vellandrucia. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds silly and it works. - Both behind a single flap? Then confirm the cap on your diesel filler is still closed ahead of raising the bottle. - Gently does it, 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 the car. If at stage two or three you find you have already poured into the diesel side, stop there. Step five stays out. ## Tregolls: already put AdBlue in your diesel tank? Then the order of things is short. Do not start your motor. The fuel pump starts on plenty of diesels the moment the ignition goes on — so leave it off. Topping up with diesel won't dilute it: rather than mixing, AdBlue drops to the base of that tank, just where the fuel is taken from. The attendants at Gulf, Texaco or another forecourt will normally lend a hand to push the car away when you ask. Your own drive around Tregolls is where it stays. Already run? Stop when it's sensible, then switch off. The next junction means where to leave when you are on the M5, over 50 miles from Tregolls. About how far did it go? Crossing Tregolls is smaller work than a run of under 10 miles towards Truro, so say. ## Our arrival in Tregolls, and what occurs next Our engineers come to your car wherever it has stopped, whether that is outside Stithians Community Primary School, near The Stithians Centre or on your own driveway. What liquid was put in, the amount, and if it ran: our engineers ask because those replies set the work and price. No one heads out before you've heard the price by phone. Emptying the tank comes next, followed by a thorough flush of your system. Not like petrol, AdBlue leaves crystals and eats at certain fuel-system metals, and none of that clears out unaided. That is why it matters more. Your filter is cleaned, or replaced where it needs to be; fresh diesel goes in; and the car is tested. Your engine is fired up next and tested to be sure it runs properly, all before our technicians head off. Unstarted cars mostly mean a half-hour visit from the moment we arrive. The kit is fine on a live filling station, and quiet enough for a residential street late at night. The insurer will ask for the engineer's report and the VAT invoice, and you get both once this job is done. Payment comes on the day, with no money upfront. It is worth checking your insurance while we travel to you: misfuelling cover comes with many policies. ## About Tregolls, briefly Tregolls is a locality situated on the banks of a river in Cornwall, with a relatively small population of around 1225 residents. Tregolls is characterized by its detached housing and rural setting, lying approximately 115 metres above sea level. Tregolls is close to the city of Truro, which is about 7.7 miles away, and is also near other places such as Stithians and Hendra. Tregolls is located in the South West region of England, about 238.3 miles from London. ## AdBlue drains across Cornwall, Tregolls included As a small village, Tregolls shares its vans nearby areas — Hendra, Seaureaugh Moor — all the way across TR postcodes and the wider area around them. Fastest of all: quote a TR3 7 postcode for the van. Moving the car isn't necessary. Our engineers drain it where it is — a side street close to St Stythian's Church, a lay-by on the way to Half Moon Wood, a drive. Guessing won't help at the back of United Methodist Free Church, close to a boundary, or somewhere awkward to pin down; ring and ask. ## Tregolls motorists: the short version Before you pour, read the cap. If AdBlue has gone in the diesel tank all the same, leave it off then call 0333 366 0103. Petrol in Diesel clears it where it sits, anywhere across Cornwall.