Petrol in a Diesel Car in Harlech: How Worried Should You Be?
Provided it hasn't been started, worry less than you likely are. Until your ignition primes your pump, your starter turns, or your vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which makes the truthful reply to that first Harlech query — "have I ruined it?" — usually no. To keep the vehicle like that, phone Petrol in Diesel and leave the engine alone. Further down, you will find what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
What petrol in a diesel does to the engine
Passing through a motor, diesel does two jobs at the same time. It combusts, and before it burns it protects. Designed to extremely fine clearances, the injectors and the pump rely on the diesel flowing through them to keep their surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does badly. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and strips out the lubrication your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the rattling starts.
Together, those leave the shape of the issue plain. The harm is done by movement, not by contact. Where that petrol is only in the tank, it is a problem of fuel, nothing more. Whatever a worn pump sheds goes on, borne by the fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical fault starts.
Four situations our technicians see around Harlech: how serious is petrol in a diesel?
Fuelled, and not started: nothing beats it. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol held in your tank alone, it's drained and rinsed on the spot, and nothing more is needed.
Started for a second, or only the ignition on. Once primed, your system has pulled petrol from the tank as far as the fuel filter and the fuel lines. Drain, flush, deal with your filter: still normally simple.
A couple of miles driven, and your pump has spent each of them running on diluted fuel. How hard the vehicle was driven counts as much as how far, and this work takes in your tank, the fuel lines, your filter and clean fuel through the entire circuit. A school run to the local primary school is one matter. Getting as far as Bangor, under 50 miles away, makes a very different task — as does any miles on the M53, over 50 miles from Harlech, with the engine running hard all the way.
Driven on till it protested — knocking, smoke, an uneven idle, a soft throttle. The fuel isn't acting like diesel any more, and the engine is saying so. Pull up on the spot — on the verge on Twtil, at the kerb, down a side road — and do not move it. Permanent damage is very uncommon when a car is pulled over early, and the drain and flush that still come first sort it out.
Stories Harlech drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a bigger tank of the same mix. Percentage is not how a diesel fuel system tolerates petrol, however much that guidance supposes.
If anything, the reverse holds. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that's how a newer diesel moves its fuel, and so the protection matters for more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most people than any other. The motorist of a petrol motor fed diesel usually stops, since it will not run, and the harm stops with them. Feed petrol to a diesel and it generally starts, idles and pulls away as if nothing happened — all the while its pump is wearing. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a different fault. It doesn't put back what petrol has thinned, and the petrol is still in the tank afterwards.
Once the motor has run, part of the petrol is in the filter and the lines, not that tank — and the next start pulls it right back through your pump. So the myth "drain the tank yourself and you're sorted" does not stand up. It is also genuinely hazardous to drain petrol into a can at the kerbside.
Why petrol in a diesel occurs at all
It's rarely carelessness, and nobody does it on purpose. One way only, because of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
Routine and your car falling out of step is when it takes place. Courtesy car, hire car, or a car that is brand new. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill on the way to the nearest station. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it occurs. With rain, a call arriving, or a car full of children to deal with, the hand just does what it always has.
Harlech people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Trust the label on the petrol pump, not the colour.
- Inspect your filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on your first fill in any car you don't know.
- One of each in the house? Label the key to your diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems silly. It does the trick.
- Put the phone away. This is an easy mistake to make whilst you're thinking about something else.
- Add-on devices are available for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Less petrol means a thinner mix, so stop as soon as you realise — while remembering that the next stage is unchanged. It's still not to start the car.
Put petrol in a diesel in Harlech already?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. The attendants on the forecourt — whether at Essar itself or wherever you filled up — will usually help push it clear of the pump if you ask. Phone 0333 366 0103 next, with three facts — your fuel, the approximate volume, and if it has run.
If it was AdBlue and not petrol, say so. That is a different issue — corrosion and deposits instead of lost lubrication — and it has its own page for Harlech.
Why one petrol in a diesel job in Harlech costs more than another
Four different tasks sit behind the four situations above — which is why there is no fair single quote. Which of them you're in is mostly what shifts your cost. Where the vehicle is matters too, and whether a van can safely get to it, after the share of petrol to what the tank takes.
What went in, how much, and if it's run — three questions our engineers ask before costing, not after, for exactly that reason. Those replies are what turn a range into one firm number.
About Harlech, briefly
Harlech is a coastal town in northwest Wales, situated on the southern shore of Snowdonia, with a population of around 1261 people. Harlech sits at an elevation of 65 metres, overlooking Cardigan Bay, and is characterised by its predominantly detached housing stock. Harlech is close to nearby villages such as Lower Harlech, Llanfair, and Llandanwg, and is approximately 25 miles from the city of Bangor. Harlech has a distinctive setting, with the town's buildings and streets arranged to take advantage of the coastal location.
Harlech and Gwynedd: where our fuel drain cover reaches
The teams answering petrol in diesel calls in Harlech, in the LL postcode area, equally work the places around it, Lower Harlech, Llanfair and Llandanwg included. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our engineers work, and the vehicle doesn't need to move to us.
Harlech: still at the petrol pump?
The best position there is, then — that is where you are. Keep the car switched off, and ring.