How Worried Should You Be? Petrol in a Diesel Car in Antron
Probably less than you are now — provided no one has started it. "Have I wrecked it?" is the first thing anyone in Antron asks, and the honest answer is normally no, since petrol resting in a diesel tank harms nothing till it is dragged through the fuel system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to phone, with your motor kept off, so it stays that way. What petrol really does to a diesel, how to judge how far it's travelled, and how to keep it from happening again: that is the remainder of this page.
Inside your engine: what petrol in a diesel does
Two jobs fall to diesel on its route round a motor. It protects first, and only then does it burn. Designed to extremely fine clearances, the injectors and your pump rely on the diesel flowing through them to keep their surfaces from wearing against one another.
The second job petrol does not do at all, and the first it does poorly. It's runnier than diesel and strips away the lubrication your fuel system depends on, so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from.
Put these together and the shape of the problem is clear. The damage is done by movement, not by contact. Any tank with petrol in it is a fuel issue. Whatever a worn pump sheds travels on, borne by the fuel, into the fuel injectors further along, which is why a pump that has worked on the petrol is where a mechanical fault begins.
Petrol in a diesel around Antron: how serious is it? Four situations
Fuelled up, not once started. The best case there is. Only that tank has petrol in it, and so the task is clearing your tank and flushing the system where the vehicle sits. This situation can only truly happen on a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or just your ignition on. With your system primed, the lines and filter now contain petrol that has come from the tank. Still usually easy: drain, flush, and the fuel filter dealt with.
The pump has spent a few miles on thinned fuel — that is what driving the car does. The work is the tank, your lines, the filter and fresh fuel through the entire circuit, and how hard the car was driven counts as much as how far. On the school run to Mabe Community Primary School, the mileage is short. Driving as far as Truro, under 10 miles away, makes a very different job — as does any miles on the M5, over 50 miles from Antron, with your engine working hard the whole time.
Driven till it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer acting like diesel. Pull up on the spot — on the verge on Penwarne Road, at the kerb, down a side road — and don't move it. A vehicle stopped soon very rarely has long-term damage, since the drain and the flush-through, which still go first, take care of it.
Petrol in a diesel stories Antron motorists hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and closer to the opposite. Lubrication counts more on current diesels, not less, since their fuel passes through smaller components at higher pressure.
One myth that catches people off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it normally won't run, and so the motorist stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump wears. Running is not the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different issue. What petrol has diluted remains thinned, and that petrol stays in your tank regardless.
The next start draws petrol back round the pump out of the lines and your filter, where some of it sits once the motor has been run. That's why draining the tank yourself does not leave you sorted — a myth. Also, a can of petrol drained by the roadside is genuinely hazardous.
How petrol ends up: petrol in a diesel
Nobody does it on purpose, and it is seldom carelessness. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it straightforward.
When habit and your car stop matching, it takes place. Any car that is new to you — a hire car, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. Your normal forecourt, its pumps now in a different order. Fuelling up in a rush on the way to Penryn, with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. With rain, a call arriving, or a car full of children to deal with, the hand simply does what it always has.
How to avoid petrol in a diesel on your next fill-up around Antron
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the petrol pump's label; the colour is only a hint.
- In a motor you do not know, look inside the flap over the filler or at the cap before the first fill: plenty of vehicles state the fuel type there.
- One of each in the house? Mark your key to the diesel — a coloured fob, a sticker — since meaning to remember is not enough.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Mistakes like this are straightforward to make while your mind is on something else, so your phone goes away.
- Add-on devices exist for vehicles without one, and some diesels are built with a filler that will not take a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol in the tank means a weaker mix. What to do next doesn't change, though — still do not start the vehicle.
Already put petrol in a diesel around Antron?
The order of things is brief, then. Leave it unstarted, with the ignition off as well. Ask the attendants to help you roll it clear of the petrol pump if you are still at the forecourt, whether that is Asda or anywhere else. What got in, roughly how much, and whether it has run: tell us those when you ring 0333 366 0103.
If it was AdBlue and not petrol, say so. That's a different issue — corrosion and deposits instead of lost protection — and it has its own page for Antron.
One petrol in a diesel task around Antron costs more than another. Why?
There is no fair single price for this, since the four scenarios above are four separate tasks. What shifts the cost is mostly which of them you are in. Where the vehicle is matters too, and whether a technician can safely get to it, after the ratio of petrol to what the tank holds.
That is why we ask three queries before pricing instead of after: what was put in, how much, and if it's run. A range turns into a straight figure when those replies are in.
About Antron and its setting
Antron is a small hamlet situated on the shores of a lake in Cornwall, with a rural setting and an elevation of around 135 metres. Antron lies close to the city of Truro, which is approximately 8 miles away, and is near other small settlements such as Trenoweth and Mabe Burnthouse. Antron has a population of around 2717 people, who mostly reside in detached houses. Antron is located in the South West region of England, about 237 miles from London.
Antron and Cornwall: where our fuel drain cover runs
Trenoweth, Mabe Burnthouse and Lamanva are among the places near Antron that the same teams work, answering petrol in diesel calls across Antron's TR postcode area. You need not bring your car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
Antron: still at the petrol pump?
Nothing beats it: that is where you now are. Turned off it remains; then phone.