Llanwyddelan: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you likely feel. Petrol resting in a diesel tank does nothing to the engine until something draws it through the fuel system — the ignition priming the pump, the starter, or the drive on its own. So the fair answer to the first query anyone around Llanwyddelan asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to phone, with the motor left off, so it remains that way. The rest of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Inside the motor: what petrol in a diesel does
Two tasks fall to diesel on its journey round a motor. Before it burns, it protects — and then it combusts. What stops the surfaces inside your high-pressure pump and the fuel injectors from grinding against each other is the diesel flowing through them — they are designed to very fine clearances.
Poorly at the first, not at all at the second: that is petrol. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and strips out the protection the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where the clattering starts.
Put these together and the shape of the problem is plain. Not contact but circulation is what does the harm. All a tank with petrol in it amounts to is a fuel issue. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
Llanwyddelan, petrol in a diesel: four situations, from mild to major
Fuelled, and not started: no case is better. Only the tank has petrol in it, so the task is draining that tank and rinsing the fuel system where the car stands. This situation can only truly happen at a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a moment. Petrol has come out of the tank and got to the filter and your lines, because the fuel system has been primed. Still normally straightforward: drain, flush, and the filter dealt with.
Driven a couple of miles. Now your pump has spent those miles running on diluted fuel. The work is the tank, the fuel lines, the fuel filter and clean fuel through the entire system, and how hard the vehicle was driven counts as much as how far. Short trips, like the school run to the local primary school, are one thing. Very different once more: a trip to Wrexham, under 50 miles away, or some miles on the M54, under 50 miles from Llanwyddelan, where the motor never stopped working hard.
Driven on until it complained — clattering, smoke, a ragged idle, a soft throttle. The fuel isn't acting like diesel any more, and the motor is telling you. Leave it wherever it has stopped: a lay-by, a side street, the verge on B4389. What goes first is still the drain and flush-through, and that deals with it, with permanent damage very uncommon when a car is pulled over early.
Stories Llanwyddelan people hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — the tank simply carries more of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, whatever that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through more precise components: that's how a current diesel handles its fuel, and so the protection counts more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there is no harm done." Diesel in a petrol motor generally means a motor that won't run: the driver stops, and so does the harm. While the pump wears, a diesel fed petrol usually starts, ticks over and drives away as if nothing has happened. Fine and running aren't the same thing.
An outdated workaround for a distinct issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." What petrol has weakened remains weakened, and the petrol stays inside your tank regardless.
The next start sends petrol back round the pump from your lines and your filter, where some of it ends up after the engine has run. That's why draining the tank yourself doesn't sort it — a myth. On top of that, petrol cleared into a can by the road is genuinely risky.
Why petrol in a diesel happens at all
A careless moment is seldom the cause, and no one means to do it. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
Habit and the vehicle getting out of step is when it takes place. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. Your usual forecourt, its pumps now in a different order. Filling up in a rush on the way to Newtown (Powys), with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that's when. With rain, a call arriving, or children to deal with, the hand just does what it has always done.
Avoiding petrol in a diesel next time you fill up in Llanwyddelan
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in a new vehicle is the time to check your filler flap — inside it, or on the cap, plenty of cars state which fuel they take.
- Mark the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems silly. It does the trick.
- Mistakes like this are straightforward to make whilst your mind is on something else, and so the phone goes away.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- The moment you notice, stop: less petrol in that tank means a thinner blend. What to do next does not change, though — still don't fire it up.
Already put petrol in a diesel around Llanwyddelan?
In that case, there is only a short order of things. Do not fire it up, and do not turn your ignition on. Ask the attendants to help you push it clear of the pump if you're still at the forecourt, whether that is the nearest petrol station or somewhere else. What was put in, about how much, and whether it has run: tell us those when you ring 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Llanwyddelan, since AdBlue brings corrosion and deposits rather than lost lubrication.
One petrol in a diesel job around Llanwyddelan costs more than another. Why?
The four scenarios above are four separate tasks, so no single quote for this would be honest. Chiefly, the cost shifts with which situation you are in. The ratio counts next, meaning how much of the tank is petrol, and then the position of the vehicle and whether getting to it is safe for a technician.
Three questions come first, before quoting, rather than after — what was put in, how much, has it run — and that is the reason. A range turns into a straight figure once the replies are in.
About Llanwyddelan and its setting
Llanwyddelan is a small hamlet situated on the banks of a river in Powys, with an elevation of 224 metres above sea level. Llanwyddelan lies near several other small settlements, including Dwyrhiw, New Mills, and Dolymelinau, and is approximately 34 miles from Wrexham. Llanwyddelan is characterised by its detached housing and rural setting, with the nearest major city being Wrexham. Llanwyddelan has a population of around 558 people.
Fuel drain cover in Llanwyddelan and across Powys
The teams answering petrol in diesel call-outs around Llanwyddelan, in the SY postcode area, equally work the locations near it, Dwyrhiw, New Mills and Dolymelinau among them. Our technicians drain wherever the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Llanwyddelan: still at the petrol pump?
The best spot there is, then — that's where you are. Keep the vehicle turned off, then ring.