Ebley: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, if it has not been started. Petrol resting in a diesel tank does nothing to the motor till something pulls it through your fuel system — the ignition priming the pump, the starter, or the drive on its own. So the truthful answer to the first query everyone in Ebley asks, "have I wrecked it?", is generally no. Keep it like that: leave your engine off then call Petrol in Diesel. Below, this page sets out 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
Two tasks fall to diesel on its journey round a motor. Before it combusts, it lubricates — and then it combusts. Extremely fine clearances are built into the fuel injectors and your high-pressure pump, and only your diesel flowing through keeps those surfaces from grinding together.
Petrol handles the first job poorly and the second not at all. It's thinner than diesel and strips away the lubrication your fuel system rests on, and 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 knocking comes from.
The shape of the trouble is plain when you put those together. It's movement that causes the damage, not contact. Where that petrol is only inside the tank, it is a fault of fuel, nothing more. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Four situations our engineers see around Ebley: how serious is petrol in a diesel?
The best case there is: filled up, not once started. Just the tank has petrol in it, and so the task is draining that tank and rinsing the system where your car sits. This situation can only really take place at a forecourt: anywhere else, the vehicle got there by being driven.
Ignition on, or started for a moment. The fuel system has been primed, so petrol has left the tank and got to the fuel filter and your lines. Drain, flush, deal with the fuel filter: still usually easy.
Driven a couple of miles. Now your pump has spent these miles labouring on thinned fuel. The work is your tank, the lines, the filter and clean fuel through the entire system, and how hard the car was driven matters as much as how far. On the school run to Foxmoor Primary School, the distance is small. Any distance on the M5, under 5 miles from Ebley, means the engine has worked hard throughout, and a run to Gloucester, under 10 miles away, makes a very different job too.
Driven on till it protested — knocking, smoke, a ragged idle, a dead throttle. That is your motor telling you its fuel no longer is acting like diesel. Stop wherever you are — the verge on Bridge Road, a lay-by, a side street — then leave the car there. Lasting damage is very unusual when a car is stopped soon, and the drain and flush that still come first deal with it.
Myths Ebley 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." Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. The assumption behind the guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through more precise components: that is how a modern diesel handles its fuel, so the protection counts more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools people. Feed diesel to a petrol motor and it normally won't run, so the driver stops — and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. Fine and running aren't the same at all.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. What petrol has diluted stays thinned, and that petrol remains in that tank regardless.
Myth: "Drain the tank yourself and you're sorted." Once the engine has been run, some of the petrol is no longer in that tank: it's in the fuel filter and your lines, and it goes straight back through your pump at the next start. It's also genuinely dangerous to drain petrol into a can at the roadside.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
The moment routine stops matching your car is the moment it occurs. A car that is new to you — a hire car, on loan as a courtesy car, or just bought. One petrol and one diesel on the driveway of the same household. A well-known forecourt with the pumps in a different order. A hurried fill on the way to Stonehouse with a train to catch. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Add a back seat full of children, a phone call or rain, and the hand wins.
How to avoid petrol in a diesel at your next fill-up in Ebley
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the pump's label; the colour is just a clue.
- Many cars state the fuel type inside your filler flap or on the cap, and so check there on the first fill in any vehicle you do not know.
- One of each in the household? Mark the key to your diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fuel a hired or new motor, say "diesel" aloud. Silly, yes, yet it works.
- Mistakes like this are easy to make while your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the petrol pump.
- As soon as you notice, stop: less petrol inside the tank makes a thinner blend. What to do next doesn't change, though — still don't fire it up.
Petrol already in a diesel around Ebley? Start here
The order of things is brief, then. Starting it is out, and so is turning on your ignition. Yet on the forecourt, at Esso or anywhere else? Ask the attendants to help you roll the vehicle clear of the pump. Then phone 0333 366 0103 and tell us what went in, about how much, and whether it has run.
If it was AdBlue instead of petrol, say so. That is a different fault — corrosion and deposits instead of lost lubrication — and it has its own page for Ebley.
One petrol in a diesel task in Ebley costs more than another. Why?
An honest single price does not exist here: four situations, four separate jobs. The scenario itself does most of the work of moving your cost. Where your car is matters too, and whether a van can safely reach it, after the share of petrol to what that tank takes.
Three questions come first, before quoting, instead of after — what got in, how much, has it run — and that is the reason. The answers change a range into a straight figure.
About Ebley and where it is
Ebley is a suburban area in Gloucestershire, situated on the riverside at an elevation of 38 metres, with semi-detached housing being the predominant type of accommodation. Ebley lies near the cities of Gloucester and the surrounding areas of Hamwell Leaze, Dudbridge, and Cainscross. Ebley is located approximately 92.6 miles west of London, and its population is around 2707 residents. Ebley has a relatively low elevation, typical of the riverside areas in the region.
Ebley and Gloucestershire: where our fuel drain cover runs
Our vans answering petrol in diesel jobs in Ebley, in the GL postcode area, also work the places near it, Hamwell Leaze, Dudbridge and Cainscross among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we drain, and the car does not need to come to us.
At the pump in Ebley, right now?
Then, you could not be in a better place. Keep it off. Phone.