--- title: AdBlue in a Diesel Tank Lanstephan? Read This canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/lanstephan-cornwall/ location: Lanstephan county: Cornwall latitude: 50.647350 longitude: -4.362780 service: AdBlue in a Diesel Tank updated: 2026-10-21 --- # Avoiding AdBlue in a Diesel Tank in Lanstephan: Why It Happens Keep your motor and ignition off and call 0333 366 0103 first — reading can wait if AdBlue is already in your diesel tank. Normally, when the motor hasn't turned, it's drained and fully purged where the car is around Lanstephan. If you're reading before it has happened, the remainder of this page is about why it takes place and how to make sure it does not. ## AdBlue in a diesel motor: two tanks, two fillers Not one liquid but two: that's what many modern diesels near Lanstephan and Dutson carry, with diesel feeding your motor. The exhaust, not your engine, is where AdBlue goes: dosed into the fumes to clean it, from its own tank. Different tanks, separate fillers. Other cars keep the AdBlue filler in the boot or under the bonnet; a lot more place both side by side under one flap. At the petrol pump, the diesel side gets filled constantly. The AdBlue side is fuelled far less commonly, normally from a bottle, and normally by someone who has to stop and think where it goes. The slip lives in that gap. ## How does AdBlue in your diesel tank happen around Lanstephan? Carelessness rarely explains it. What does is three things lining up together. The warning comes first. As AdBlue runs low the vehicle tells you, and if it runs out completely, your vehicle goes into limp mode. So the top-up is done in a hurry: on a driveway off St Mary's Road before work, or in the car park outside White Horse Inn on the way home. The old car's filler is where the hand goes — yet a hire car, a new motor or a company car keeps the fillers somewhere else. That is a second thing: a strange motor. 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 after it has started. Newport or the middle of Lanstephan: it takes the same few seconds either way. ## How to tell the AdBlue filler from the diesel one Look at these first, at a forecourt in Lanstephan or a drive out in Launceston. Seconds, no more. - Position can mislead; the cap doesn't. AdBlue caps are often blue or bear the name "AdBlue" — diesel ones normally do not. - Plenty of motors fit AdBlue the smaller neck of the two. - Look inside your fuel flap: many cars carry a label there showing which fuel goes where. - In your boot or under the bonnet: that is where the filler is 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 collect a hire or company car from somewhere like the car park outside Gunnislake. ## Topping up AdBlue without it reaching your diesel tank A routine for the day the light comes on, wherever around Cornwall that is. - Not in a rush on the side of Cross Lanes, not on a slope, not with the engine running: park then switch off first. - Find the AdBlue filler and read the cap. Say "AdBlue" out loud as you unscrew it. It sounds daft and it does the trick. - Leave your diesel cap on. If both sit under one flap, check your diesel cap is still closed before you lift the bottle. - Stop once your tank fills or the bottle is empty; until then, pour gently through the built-in spout. - Close the cap, and check again — confirm your diesel cap remained closed the whole time. After that, start the vehicle. Find at step two or three that it has already gone into the diesel side? So stop right there. Step five stays off limits. ## Already put AdBlue in your diesel tank in Lanstephan? Brief list, then. Top of that: the motor remains unstarted. On plenty of diesels your ignition alone runs the fuel pump, and so do not switch the vehicle on. Do not top up with diesel to thin it: AdBlue does not mix with diesel, it sinks to the bottom of the tank, where your fuel is sucked from. Ask the attendants to help push the car clear of the pump if you're on a forecourt — the BP, the another forecourt nearby or somewhere else. Leave it where it is if you're on your own driveway around Lanstephan. Stop as soon as it is safe and switch off, if your motor has already run. On the M5, under 50 miles from Lanstephan, that means the next junction. A short hop across Lanstephan is a smaller job than a run towards Plymouth, under 25 miles away, so tell us about how far it went. ## Our arrival in Lanstephan, and what takes place next Our van comes to the vehicle anywhere it has come to rest — your own drive, beside St Stephans Community Hall, or by St Stephens Community Academy. The replies settle this work and our quote, so our technicians ask what got in, about how much, and whether it has run. On the phone call itself, you hear the quote — ahead of dispatch. The system is then rinsed thoroughly, once your tank is drained. Unlike petrol, AdBlue leaves crystals and attacks certain fuel-system metals, and none of it washes away unaided. Hence it matters more. Filter flushed or, if it must be, replaced; fresh diesel in; then a test of your car. After that our technicians start it and check it runs smoothly before leaving. Using pumps fine on a working forecourt and quiet enough for use outside a house at night, most jobs where the engine hasn't run take about half an hour after our engineers are there. Payment is on the day, not upfront, and you are given the paperwork your insurer wants: an engineer's report and a VAT invoice. It's worth checking your insurance while we travel to you: misfuelling cover is included with many policies. ## About Lanstephan and where it is Lanstephan is a suburban area situated on the outskirts of a larger settlement in Cornwall, with its riverside location offering scenic views. Lanstephan sits at an elevation of 138 metres, and its proximity to nearby places such as Newport and St Stephens makes it a convenient residential location. Lanstephan is characterized by its predominantly terraced housing stock, which reflects the area's history of development. Lanstephan is located approximately 21.5 miles from Plymouth, making it a commuter base for the city. ## AdBlue drains across Cornwall, Lanstephan included As a residential suburb, Lanstephan shares its vans nearby areas — St Stephens, St Thomas — all the way across PL postcodes and the surrounding area around them. Quote a postcode that starts PL15 8, and the van gets there fastest. The car remains where it is. Our technicians drain it where it is — a side street close to St Stephen, a lay-by on the way to Launceston Castle, a drive. Tricky to pin down, like the back of St Thomas the Apostle? Close to a county line? Checking is better than guessing, and so phone. ## The short version for Lanstephan people Read the cap before you pour. Petrol in Diesel drains it on the spot, anywhere in Cornwall, if AdBlue has gone in the diesel tank all the same — so leave it off and call 0333 366 0103.