--- title: AdBlue in a Diesel Tank St Ruan — Don't Start It canonical: https://www.petrolinadieselcar.co.uk/adblue-in-diesel/st-ruan-cornwall/ location: St Ruan county: Cornwall latitude: 49.991350 longitude: -5.187110 service: AdBlue in a Diesel Tank updated: 2026-10-07 --- # St Ruan: AdBlue in the Diesel Tank? Leave It Off With AdBlue in the diesel tank, your ignition stays off and so does the engine. Urea dissolved in water is all AdBlue is. It doesn't burn, it doesn't mix with diesel, and the harm it does starts when your fuel system draws it in. Caught before the engine has been run, AdBlue in a diesel tank is usually a drain and a thorough flush, done where the vehicle is around St Ruan. Before you do anything else, ring 0333 366 0103. ## AdBlue in the diesel tank around St Ruan: the first few minutes Do: - Remove your keys, which stops anyone switching the electrics on. - Hazards on, if moving traffic is anywhere close. - Hold on to the till receipt or the empty bottle, so you can tell us what got in and roughly how much. - Tell us a postcode starting TR12 7, or whatever street is nearest, and the van finds you directly — so call wherever you are. Not to do: - No starting your motor — not briefly, not to shift the vehicle. - Don't switch the ignition on. On plenty of diesels that alone runs the fuel pump. - Adding extra diesel does not help: AdBlue separates out instead of blending. - Leave it where it is instead of driving it anywhere, even a short stretch down New Road. - Draining that tank yourself by the road isn't worth trying. Ask the attendants to help you roll the vehicle off the pumps if you are at a forecourt around St Ruan, whether it is the Kynance Garage or somewhere else. If you are on your own drive, leave it precisely where it sits. ## AdBlue in a diesel tank: what it does The engine is not what AdBlue is made for; your exhaust is. Its own tank holds it, and from there it's sprayed into the exhaust, and there it treats the fumes. A fuel pump is not made to cope with it, and AdBlue was never intended to travel through one. Tipped in with your diesel, it keeps separate rather than blending — quite unlike fuel. It sinks, because it's denser than diesel, and pools low where the intake takes its fuel from. Easiest of all: a vehicle that had AdBlue in Poltesco overnight and has not been started since. The AdBlue waits at the foot of that tank, untouched — though it would be first through if your motor runs, ahead of any diesel at all. It does two kinds of harm from there. Crystals and corrosion. As the water dries, it leaves urea that crystallises in filter elements and tiny passages; and, because it eats at some metals, every part it touches suffers for as long as it remains inside. A motor left standing around St Ruan with AdBlue already in its lines is worse by the morning; one with AdBlue just in its tank is not. Diesel protects the high-pressure pump and every injector as it flows; water gives none of that, and that is a separate kind of harm. ## Petrol or AdBlue in a diesel: why AdBlue is frequently worse Put petrol in a diesel at the another forecourt nearby and you have an issue of thin fuel. It mixes with your diesel, and while it's inside the tank it does no harm; the harm comes from running the engine on it. AdBlue in a diesel is another matter: not thin fuel, but no fuel at all. It doesn't burn, so it can't just be run through. Nor can it be thinned, because it splits again — and the following fill won't clear away deposits or corrosion. So the flush counts more here, and trying your engine "to see", in the heart of St Ruan or out in Treal, does more harm than nearly any other error. As with petrol, there is good news. Wherever across Cornwall your vehicle has stopped, an unstarted motor leaves the AdBlue still in the reservoir: the simplest bit of a fuel system to clear. ## How AdBlue ends up in a diesel tank in St Ruan It's not deliberate. Many cars keep the AdBlue inlet alongside the diesel inlet, now and then behind a single flap, and muddling them up is easy in poor light. Mostly it happens with a bottle bought on the way home and poured in on the drive, not at the forecourt. Mostly, it happens in one of a couple of familiar ways. Midway through the drop-off, the dashboard flags it up, and outside Grade-Ruan CofE Primary School the refill is rushed. A bottle is poured in at the end of the day on a drive just off Chapel Terrace. Or a driver new to that flap refills the car in dim light, stopped in the car park outside The Cadgwith Cove Inn. It crops up the most in a rental, a new vehicle, a company vehicle, or the other motor of a home with one of each fuel types — the vehicles drivers know least. Wherever around Cornwall, St Ruan as well, the mistake doesn't change, and neither does the first response: leave it off. ## AdBlue in the diesel tank in St Ruan, and your engine started? The AdBlue has left the tank, then. Your filter and lines have had it sucked through, and any running time carries it on to the high-pressure pump and every injector. Lumpy running, smoke, dropping power, dashboard warnings or stalling: any might appear, perhaps midway across St Ruan or returning from Sea Acres 9 hole course. Once you safely can, pull over then switch everything off — without turning it on again to see. With each start, more of that is pulled through. St Ruan lies over 50 miles from the M5; if you were on it, exit at the next junction and stop somewhere safe rather than carrying on. How far it went matters. A couple of hundred yards across St Ruan to the car park by St. Ruan's Well is a very different job from a run towards Truro, under 25 miles away, with the AdBlue reaching further into the system with each mile. About how far it had come is worth telling us. There is more to clean out once the engine has been run, and our engineers do all of it where your car has stopped. Caught quickly, it very seldom leaves long-term damage. ## Emptying AdBlue in a diesel around St Ruan: what it takes Anywhere it has come to rest in St Ruan — a forecourt, a layby, a driveway, a road beside St Rumon — the van comes to your car. Before anything else we ask what went in, about how much, and whether the engine has been run, because those replies determine this work. The contaminated diesel and the urea leave together after your tank is emptied, right there. The system is purged thoroughly, which matters more with AdBlue than with petrol, because what it leaves behind does not rinse out on its own. Clean diesel goes in after the fuel filter is flushed — or swapped, when it needs to be — and then your car is tested. Not run? Then count on roughly half an hour once we are there for most jobs. Low-noise enough to use outside a house at night, and safe on a working forecourt, the pumps are explosion-proof. Lastly, the system is primed with clean diesel. Whether it is a parking bay outside Penmere or a drive around St Ruan, that is where our engineers fire it up and you drive off. Before leaving, we confirm it's running correctly with new diesel in. Because the job is done in its entirety where your car is, a garage never comes into it. You get a VAT invoice and an engineer report later on, which is what insurers want. ## About St Ruan St Ruan is a small coastal hamlet in Cornwall, situated near the Lizard Peninsula and close to the villages of Ruan Minor and Grade. St Ruan sits at an elevation of 43 metres, overlooking the surrounding coastline and within a short distance of the nearby fishing village of Cadgwith. St Ruan has a population of around 546 people, predominantly living in detached houses. ## AdBlue drains across Cornwall, St Ruan included Our vans that answer AdBlue call-outs around St Ruan also cover the places round it, Ruan Minor, Grade and Cadgwith among them, and most of Cornwall beyond, across the TR postcode area. Guessing doesn't help by a county line or somewhere hard to pin down; ring and ask. No moving is needed. In St Ruan, a rural hamlet, a van that comes to you works: your vehicle is drained where it stands, be it on a driveway, a side street, a parking area or a filling station. ## What AdBlue in a diesel tank costs to put right around St Ruan Each job is different, and so not one fixed quote is fair. Three things move the price: whether the motor has run and for how long, how much AdBlue got in, and where your car is. That last one turns on whether a van can get to it safely, and an open drive is simpler than a tight space behind St Mary. What got in, how much, plus if it ran: each St Ruan enquiry opens with exactly that, before a quote, not afterwards. Once they are answered, a range becomes one fixed number. Quoted on the call before the van sets out, it is settled on the day — card or phone, no deposit. Check your insurance while we are on the way: many carry misfuelling cover. ## In St Ruan and still next to your car? Then the most helpful thing you can do is nothing to the vehicle. Engine off, keys out, ignition off. Ring 0333 366 0103 then tell us it's AdBlue, roughly how much, and whether it has run. Petrol in Diesel takes it from there, around St Ruan or anywhere around Cornwall.