--- title: AdBlue in a Diesel Tank St Eval: Explained canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/st-eval-cornwall/ location: St Eval county: Cornwall latitude: 50.477370 longitude: -4.983710 service: AdBlue in a Diesel Tank updated: 2026-10-02 --- # Preventing AdBlue in a Diesel Tank in St Eval: Why It Happens Stop here for a moment if your diesel tank already has AdBlue in it: ignition off, motor off, then ring 0333 366 0103. Around St Eval, catching it before the motor runs usually means draining and a full flush where it stands. Nothing happened yet? Further down, the page explains the reasons it takes place and the ways to prevent it altogether. ## AdBlue in a diesel car, and its separate tank Many newer diesels on the roads round St Eval and Penrose carry two liquids, not one. Diesel goes to your motor. Its own tank holds it, and from there it goes to the exhaust, and there a spray cleans the fumes. Every tank has a filler of its own. Some cars put the AdBlue filler in your boot or under the bonnet; a lot more place both together behind one flap. Diesel gets filled on every filling station call-out, again and again. Far less commonly, the AdBlue side is filled — normally from a bottle, by someone working out where it goes. That gap is where the error lives. ## St Eval: how AdBlue in your diesel tank happens Carelessness seldom causes it. Instead is three things lining up at once. Haste comes from the warning. Your car warns you as AdBlue runs low, and an empty tank puts the vehicle into limp mode — so the top-up happens in a rush, before work on a driveway off Liberator Row, or heading home in the car park outside the pub in the village. Then the vehicle is new. A hire car, a new car or a company car puts the fillers where your last one didn't, and your hand hits for the cap it would have used on the old one. Third, the spout goes in: a diesel filler or AdBlue one, it goes in as readily, and once the tip begins, nothing stops it. The same few seconds decide it, in the middle of St Eval or out in Lower Denzell. ## The AdBlue filler and the diesel filler: telling them apart Check these first, at a forecourt around St Eval or a drive out in Engollan. Seconds, no more. - The cap. The AdBlue cap is commonly blue, or marked "AdBlue". Your diesel cap normally isn't. Read it instead of going by position. - On plenty of motors, size tells: AdBlue gets the smaller filler neck. - Open the filler flap and look for a label — many motors show which belongs in each inlet right there. - The handbook shows which it is if your filler isn't next to the diesel cap: your boot, or under the bonnet. - Picking up a hire or company car, say at the car park outside Quintrell Downs? Ask the person who drove the vehicle last before leaving, not when the light goes on. ## Keeping AdBlue out of the diesel tank when you top up A routine for the day the light comes on, wherever in Cornwall that is. - Not in a rush on the side of Lincoln Row, not on a slope, not with the engine running: park and switch off first. - Daft as it sounds, saying "AdBlue" aloud as you unscrew the cap works — once you have found your filler and read it. - If both sit under one flap, check the diesel cap is still closed before you lift the bottle — then leave the vehicle on. - Stop when that tank is topped up or the bottle runs dry; before that, pour slowly using its own spout. - Only then, start the vehicle: close the cap, check once more, and make sure your diesel cap was never opened. Stop there if you find, at stage two or three, that you have already poured into the diesel side. Do not go on to step five. ## AdBlue in your diesel tank already, around St Eval? Short list, then. Top of it: your engine stays unstarted. On plenty of diesels your ignition alone runs the fuel pump, and so don't switch the car on. Diluting it with extra diesel won't work, since AdBlue settles to the bottom rather than mixing — and that's where your fuel is drawn from. On a forecourt — Gulf, Texaco or any other — the staff will normally help roll your car away, if you ask. Your own drive around St Eval is the place it should stay. Already run? Pull over when it's safe, then turn off. On the M5, over 50 miles from St Eval, that means the next junction. A short hop across St Eval is a smaller job than a run towards Truro, under 25 miles away, and so tell us roughly how far it went. ## Our arrival around St Eval, and what takes place next The van comes to the vehicle wherever it has come to rest — your own driveway, near Kernow Chocolate Cafe, or outside Trevisker Primary School. We ask what went in, roughly how much, and whether it has run, since those answers decide the work and the quote. No one heads out before you've had our quote by phone. Your system is then rinsed thoroughly, once that tank is emptied. 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 counts more with AdBlue than with petrol. After the filter has been flushed — or renewed, where needed — fresh diesel goes in, and then the car is tested. Next our technicians fire it up and make sure it runs smoothly before we leave. Most jobs are finished in about half an hour after we get there, as long as your motor hasn't run — and the pumps our engineers use are safe on a live forecourt and quiet after dark beside a house. Your insurer usually wants an engineer's report and your VAT invoice, and you get both at the end. Payment is on the day, with no deposit. Before we get there, have a look at your insurance documents; many include cover for misfuelling. ## About St Eval, for a moment St Eval is a small village in Cornwall, situated on the north coast near the towns of St Ervan and Rumford. St Eval sits at an elevation of 106 metres, overlooking the surrounding countryside and the sea. St Eval has a mix of housing types, but semi-detached homes are the most common, and it is located near the village of Lower Denzell. St Eval is approximately 15 miles from the city of Truro and 223 miles from London. ## AdBlue drains in St Eval and across Cornwall Throughout PL postcodes, our vans that cover St Eval — a coastal village — work the nearby places too, Rumford and St Ervan among them. The van reaches you fastest with a postcode starting PL27 7. There's no need to move the vehicle. We drain it where it is — a side street close to St Eval's Church, a lay-by on the way to Mawgan Porth Golf Club, a driveway. Awkward to pin down, like the back of Tumulus (site of)? By a border? Asking beats assuming, and so phone. ## St Eval drivers: the short version Read the cap before you pour. If AdBlue has gone in your diesel tank regardless, leave the car off then call 0333 366 0103. Petrol in Diesel empties it where it stands, anywhere in Cornwall.