How Worried Should You Be? Petrol in a Diesel Car in Trethosa
Not started? Then less anxious than you likely are. "Have I wrecked it?" is the first question everyone around Trethosa asks, and the truthful answer is usually no, because petrol left in a diesel tank harms nothing till it is dragged through the fuel system — by ignition priming, by your starter, or by driving. Keep it like that: leave the engine off then ring Petrol in Diesel. Below, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
The engine and petrol in a diesel: what happens
On its way through an engine, diesel does two tasks. Lubricating comes before burning; it does both. Your high-pressure pump and the fuel injectors are built to very fine tolerances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Of these two tasks, petrol handles the first badly and the second never. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on that mixture wearing itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the rattling.
Taken together, they show what shape the issue has. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel fault. Once your pump has been working on that petrol, a mechanical issue has begun: whatever is shed by a pump that is wearing is carried downstream to the injectors with your fuel.
Petrol in a diesel around Trethosa: how bad is it? Four cases
The best case there is: filled up, never started. Being on a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol kept inside the tank alone, it is drained and purged right where it stands, and nothing more is needed.
Started for a moment, or only your ignition on. Petrol has come out of that tank and got to your filter and the fuel lines, because the fuel system has been bled. Drain, flush, deal with the fuel filter: still normally straightforward.
Those few miles on the road were your pump working on fuel weakened by petrol throughout. Tank, lines, filter, then fresh fuel run through the whole circuit: that is the work, and the way your car was driven matters as much as the distance. Short trips, like the school run to St Stephen Churchtown Academy, are one thing. Getting as far as Truro, under 10 miles away, makes a very different job — as does any mileage on the M5, over 50 miles from Trethosa, with your engine working hard all the way.
Driven on until it protested — rattling, smoke, a lumpy idle, a dead throttle. The fuel is not acting like diesel any more, and your motor is telling you. Leave it where it has stopped: a lay-by, a side street, the verge on Lower Meadows. The drain and flush-through still go first, and they deal with it: if a vehicle is pulled over quickly, long-term damage is very uncommon.
Trethosa motorists and the petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A bigger tank of the same mix is all you get, since topping up takes out nothing. Percentage is not how a diesel fuel system copes with petrol, whatever that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Lubrication matters more on newer diesels, not less, since their fuel passes through finer components at higher pressure.
The myth that catches people off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually will not run, so the driver stops — and the harm stops with them. Feed petrol to a diesel and it generally starts, ticks over and drives away like nothing happened — all while its pump wears. A running engine doesn't mean fine.
An old workaround for a distinct problem is behind this one. Myth: "Add some two-stroke oil and drive it home." That petrol is still in the tank after that, and whatever it has diluted is not put back.
Myth: "Drain that tank yourself and you're sorted." Once the motor has run, some of that petrol is no longer in your tank: it is in the fuel filter and your lines, and it goes right back through your pump on your next start. It's also really hazardous to drain petrol into a can at the kerbside.
How does petrol in a diesel occur?
No one does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
Routine and the vehicle falling out of step is when it takes place. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Fuelling up in a hurry on the way to St Columb Road, with a train to catch. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
How to prevent petrol in a diesel on your next fill-up around Trethosa
- Read the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what counts.
- The first fill in an unfamiliar car is the time to check your filler flap — on it, or on the cap, plenty of motors state which fuel they take.
- One of each in the household? Mark the key to the diesel — a coloured fob, a sticker — since intending to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems silly. It does the trick.
- While you are 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 come with a filler built to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop reading the petrol pump.
- Noticing it mid-fill? Stop there and then. A thinner mixture follows from less petrol inside your tank, but your next stage remains the same: do not crank it.
Trethosa: already put petrol in a diesel?
Then the order of things is brief. Starting it is out, and so is switching on the ignition. If you are still at the forecourt — the nearest petrol station or anywhere else — ask the attendants to help you push it clear of the pump. What went in, about how much, and whether it has run: tell us that when you ring 0333 366 0103.
If it was AdBlue and not petrol, say so. That is a separate problem — corrosion and deposits and not lost lubrication — and it has its own page for Trethosa.
One petrol in a diesel task around Trethosa costs more than another. Why?
Four different tasks lie behind the four situations above — which is why there is no fair single quote. The situation itself does most of the work of moving your cost. Two things follow that: the petrol that was put in as a proportion of what the tank takes, then the place the vehicle is in and whether a van can get to it safely.
Three queries come first, before quoting, rather than after — what got in, how much, has it run — and that is the reason. The replies change a range into a straight figure.
About Trethosa
Trethosa is a small hamlet in Cornwall, situated inland at an elevation of 114 metres, approximately 9 miles from the city of Truro. Trethosa lies near other rural settlements such as Stepaside, Treneague, and Terras, and is characterized by its predominantly detached housing stock. Trethosa is a relatively small community, with a population of around 542 residents, and is located about 222 miles west of London.
Across Cornwall and in Trethosa: fuel drain cover
The teams answering petrol in diesel calls in Trethosa, in the PL postcode area, equally work the locations near it, Stepaside, Treneague and Terras among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our engineers drain, and your vehicle does not need to come to us.
Still at the petrol pump around Trethosa?
Then, you could not be in a better place. Phone, and keep it turned off.