Should You Worry? Petrol in a Diesel Car in Cwm-felin-fach
Less than you probably are, provided it has not been started. Everyone around Cwm-felin-fach starts with "have I wrecked it?", and the honest answer is usually no: petrol resting inside the tank of a diesel stays harmless until priming, cranking or driving draws it into your fuel system. Petrol in Diesel is who to call, with the engine left off, and so it remains that way. The remainder of this page explains what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Inside your engine: what petrol in a diesel really does
On its way through a motor, diesel does two jobs. Before it burns, it protects — and then it combusts. What stops the surfaces inside the high-pressure pump and your injectors from wearing against one another is your diesel flowing through them — they are designed to extremely fine clearances.
Poorly at the first, not at all at the second: that's petrol. It is runnier than diesel and takes away the protection your fuel system hinges on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the rattling comes from.
Put these together and the shape of the trouble is clear. It's circulation that causes the harm, not contact. Where the petrol is only inside the tank, it is a fault of fuel, nothing more. After your pump has been running on that petrol, a mechanical fault has begun: anything shed by a pump that is wearing travels onward to the injectors with the fuel.
Cwm-felin-fach, petrol in a diesel: four cases, from mild to significant
Filled up, and not started: no case is better. At a forecourt, and truly only there, the petrol is still confined to the tank — since anywhere else the vehicle was driven to get to it. The task is emptying and purging on the spot.
The ignition switched on, or a short start. With the system primed, the fuel lines and filter now hold petrol that has come from that tank. Drain, flush, deal with your filter: still usually simple.
The pump has spent a couple of miles on diluted fuel — that's what driving the vehicle meant. Mileage is only half of that; how hard it was driven matters equally. Either way this work includes the tank, your lines, the fuel filter and clean fuel through the whole circuit. A school run to the local primary school is one matter. A run as far as Swansea, under 5 miles away, is a very different task. So is any miles on the M4, under a mile from Cwm-felin-fach, where the motor has been working hard the whole time.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone uneven. The fuel is not behaving like diesel any more, and your motor is telling you. Whether it's the verge on Glyn Hirnant, a lay-by or a side street, stop where you are then leave it. Permanent damage is very rare if a car is stopped quickly, and the drain and flush-through that still go first sort it out.
Petrol in a diesel stories Cwm-felin-fach people hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up takes out nothing; it gives you a fuller tank of the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance supposes.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. Finer components and higher pressure are the way a newer diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up most motorists than any other. Feed diesel to a petrol motor and it usually won't run, and so the driver stops — and the harm stops with them. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, while the pump grinds. Fine and running are not the same thing.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated fix for a separate problem. It doesn't put back what petrol has weakened, and that petrol is still inside the tank later.
The next start sends petrol back round the pump out of the lines and the fuel filter, where some of that sits after the motor has run. That's why a DIY tank drain does not leave you sorted — a myth. Clearing petrol into a can at the kerbside is also truly hazardous.
Why petrol in a diesel happens at all
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol car at all. So the slip runs one way.
It takes place when habit and the vehicle stop matching. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the drive of the same household. The pumps in a different order on a well-known forecourt. Fuelling up in a hurry on the way to Llansamlet, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. The hand does what it has always done once you add rain, a phone call or a back seat full of children.
Next time you fill up in Cwm-felin-fach: avoiding petrol in a diesel
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Trust the label on the petrol pump, not the colour.
- Inspect the filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a vehicle you do not know.
- One of each in the home? Mark your key to your diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop checking the petrol pump.
- Less petrol makes a thinner mixture, and so stop as soon as you realise — while remembering that your next step is unchanged. It's still not to start the car.
Already put petrol in a diesel in Cwm-felin-fach?
Short and simple, then, is the order of things. Starting it is out, and so is turning on your ignition. If you are still at the forecourt — Asda or anywhere else — ask the attendants to help you push the vehicle away from the pump. Then ring 0333 366 0103 and tell us what went in, about how much, and whether it has run.
If it was AdBlue and not petrol, say so. That's a different fault — corrosion and deposits and not lost protection — and it has its own page for Cwm-felin-fach.
Cwm-felin-fach petrol in a diesel jobs: why one costs more than another
Four different tasks lie behind the four scenarios above — which is why there is no fair single quote. Mostly, your cost shifts with which situation you're in. Beyond that it is the share — how much petrol was put in against how much the tank takes — and after that where your car is and whether a technician can reach it safely.
Three questions come first, before quoting, instead of after — what got in, how much, has it run — and this is the reason. Those replies are what change a range into one firm number.
About Cwm-felin-fach and its setting
Cwm-felin-fach is a suburban area located on the riverside in Swansea, with an elevation of 17 metres above sea level. Cwm-felin-fach sits near the cities of Swansea and the surrounding communities of Pen-rhiw-forgan, Llanlleian-wen, and Ynysforgan. Cwm-felin-fach is characterised by its semi-detached housing and is situated approximately 3.9 miles from Swansea city centre. Cwm-felin-fach is a relatively small community with a population of around 3870 residents.
Across Swansea and around Cwm-felin-fach: fuel drain cover
Pen-rhiw-forgan, Llanlleian-wen and Ynysforgan are among the places near Cwm-felin-fach that the same teams work, answering petrol in diesel calls across Cwm-felin-fach's SA postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our engineers work, and your car doesn't need to come to us.
Still at the petrol pump around Cwm-felin-fach?
The best spot there is, then — that's where you are. Leave it turned off, then ring.