Milwr: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as no one has started the vehicle. Everyone around Milwr starts with "have I wrecked it?", and the fair answer is normally no: petrol left inside the tank of a diesel stays harmless till priming, cranking or driving pulls it into your fuel system. Keep it that way: leave your engine off then call Petrol in Diesel. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and the way to make sure you never repeat it.
The motor and petrol in a diesel: what happens
On its way through an engine, diesel does two tasks. It lubricates to begin with, and after that does it burn. What stops the surfaces inside the high-pressure pump and your injectors from wearing against one another is the diesel flowing through them — they are built to very fine tolerances.
The second task petrol does not do at all, and the first it does badly. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that's where the clattering comes.
Put those together and the shape of the issue is clear. The damage is done by movement, not by contact. A tank with petrol in it is a fuel issue. Once the pump has been running on that petrol, a mechanical issue has started: anything shed by a pump that is wearing is carried onward to the injectors with your fuel.
How bad is petrol in a diesel? Four scenarios our technicians see around Milwr
Fuelled up, not once started. The best case there is. At a forecourt, and truly only there, the petrol is still confined to that tank — because everywhere else the car was driven to reach it. The task is emptying and purging on the spot.
Ignition on, or started for a second. Petrol has left the tank and got to the fuel filter and your lines, since the fuel system has been primed. Usually little more than draining, cleaning and seeing to the fuel filter, and so still simple.
Driven a few miles. Now the pump has spent those miles labouring on diluted fuel. Distance is only half of it; how hard it was driven counts equally. Either way the work includes that tank, your lines, your filter and fresh fuel through the entire circuit. Driving the kids to the local primary school is one sort of trip. A run as far as St Asaph, under 10 miles away, is a very different job. So is any mileage on the M53, under 10 miles from Milwr, where the engine has been working hard throughout.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. That's the motor telling you its fuel no longer is acting like diesel. Pull up wherever you are — the verge on Pistyll, a lay-by, a side street — then leave the vehicle where it is. The drain and flush-through still come first, and they deal with it: when a vehicle is pulled over soon, lasting damage is very uncommon.
What Milwr people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mixture is all you get, since topping up removes nothing. Percentage is not how a diesel fuel system copes with petrol, however much that advice presumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through more precise components: that's how a modern diesel moves its fuel, so the protection matters for more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. A petrol motor fed diesel normally won't run, and so the motorist stops and the harm stops with them. Feed petrol to a diesel and it normally fires up, idles and drives away as if nothing happened — all while its pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a distinct problem. The petrol is still inside your tank afterwards, and whatever it has thinned is not put back.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol lies in the fuel filter and lines, waiting to go straight back through your pump at the next start. Draining petrol into a can by the roadside is also genuinely risky.
Why petrol in a diesel takes place so easily
Carelessness is seldom the cause, and no one means to do it. A diesel nozzle mostly won't go into a petrol car, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and only in one direction.
The moment routine stops matching your car is the moment it occurs. Courtesy car, hire car, or a motor that is brand new. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A hurried fill on the way to Flint with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: exactly when it happens. Add rain, a phone call or a back seat full of kids, and your hand does what it has always done.
Milwr drivers: how to prevent petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Check the petrol pump's label; the colour is just a clue.
- Many cars state the fuel inside the filler flap or on the cap, so check there on your first fill in any motor you do not know.
- One of each in the household? Label the key to your diesel — a bright fob, a sticker — since intending to remember isn't enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It seems daft. It works.
- Tuck your phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol inside the tank means a weaker mixture. What to do next doesn't change, though — still don't fire it up.
Milwr: already put petrol in a diesel?
Then the order of things is brief. Leave it unstarted, with the ignition switched off too. If you are still at the forecourt — Shell or anywhere else — ask the attendants to help you push the car away from the petrol pump. Ring 0333 366 0103 next, with three answers — your fuel, the approximate quantity, and if it's run.
Say so if it was AdBlue instead of petrol: it is a different fault, with its own page for Milwr, because AdBlue brings corrosion and deposits instead of lost protection.
Milwr petrol in a diesel jobs: why one costs more than another
Four different tasks sit behind the four scenarios above — which is why there's no fair single price. The scenario itself does most of the work of moving your cost. Next it's the share — how much petrol went in against how much that tank takes — and then where your car is and whether a van can get to it safely.
That is why our engineers ask three queries before costing instead of after: what got in, how much, and if it's run. Those replies turn a range into a straight figure.
About Milwr itself
Milwr is a small suburban area in Flintshire, situated on the north Welsh coast, with an elevation of 162 metres. Milwr lies near the towns of Holywell and St Asaph, and is part of a wider area that includes the communities of Dolphin and Pwll-clai. Milwr is characterized by its predominantly detached housing stock, reflecting its residential nature. Milwr is located approximately 9.6 miles from St Asaph and 177.9 miles from London.
Fuel drain cover across Flintshire, Milwr included
The teams answering petrol in diesel calls around Milwr, in the CH postcode area, equally work the locations around it, Dolphin, Holywell and Pwll-clai included. We drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump around Milwr?
The best place there is, then — that is where you are. Keep it off. Phone.