Should You Worry? Petrol in a Diesel Car in Elstead
Not started? Then less worried than you likely are. Petrol sitting in a diesel tank does nothing to the engine till something pulls it through the system — the ignition priming the pump, the starter, or the drive itself. So the fair answer to the first question everyone around Elstead asks, "have I wrecked it?", is generally no. To keep the car like that, call Petrol in Diesel then leave the engine alone. The remainder of this page covers what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Petrol in a diesel: what does it do to the engine?
Passing through a motor, diesel is doing two jobs at once. It protects to begin with, and only then does it burn. Very fine clearances are built into the injectors and the high-pressure pump, and only the diesel running through keeps those surfaces from grinding together.
Petrol does the first job poorly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump on the mixture to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
The shape of the problem is plain when you put those together. The harm is done by movement, not by contact. Petrol in the tank is a fuel fault. The beginning of a mechanical problem is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors beyond it.
Four situations our engineers see around Elstead: how serious is petrol in a diesel?
Filled but not once started — as good as it gets. Just your tank has petrol in it, so the job is emptying your tank and rinsing the fuel system where the vehicle sits. This situation can only really happen on a forecourt: anywhere else, your car got there by being driven.
Ignition on, or started for a moment. Petrol has left your tank and got to your filter and the fuel lines, since the fuel system has been bled. Normally nothing more than emptying, cleaning and seeing to the fuel filter, so still simple.
Driven a couple of miles. Now your pump has spent these miles working on thinned fuel. Tank, lines, filter, then clean fuel run through the entire circuit: that's this work, and the way your car was driven counts as much as the miles. Driving the kids to St James CofE Aided Primary School is one sort of trip. Any mileage on the M3, under 10 miles from Elstead, means your engine working hard throughout, and a run to Chichester, under 25 miles away, is a very different task as well.
Driven till it complained. Clattering, a ragged idle, smoke, a throttle that has gone soft. That is your engine telling you its fuel no longer is behaving like diesel. Stop where you are — on the verge on Thursley Road, at the kerb, down a side road — and do not move it. The drain and flush-through still come first, and they take care of it: if a vehicle is stopped quickly, permanent damage is very uncommon.
Elstead drivers and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing comes out when you top up — the tank simply carries more of the same mixture. A diesel fuel system does not accept petrol by percentage in the way that guidance assumes.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." Protection counts more on newer diesels, not less, since their fuel passes through smaller components at higher pressure.
"It starts, it drives, and so there is no harm" — the myth that catches most motorists than any other. A petrol engine fed diesel usually won't run, and so the motorist stops and the damage stops with them. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, while your pump wears. Being able to run isn't the same as being fine.
An old workaround for a separate fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." It doesn't put back what petrol has weakened, and that petrol is still inside the tank after that.
The next start draws petrol back round the pump out of your lines and your filter, where some of it ends up after the engine has run. That is why a DIY tank drain does not leave you sorted — a myth. And, a can of petrol filled by the roadside is truly risky.
Petrol in a diesel: how does it occur?
Nobody does it on purpose, and it is rarely carelessness. A diesel nozzle generally will not go into a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error simple, and only in one direction.
The moment routine stops matching the vehicle is the moment it takes place. A new vehicle, a hire car or a courtesy car. Two motors on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps arranged differently. Rushing for a train outside Milford (Surrey) and filling up en route. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Next time you fill up around Elstead: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on every forecourt. The label is what counts.
- Plenty of motors state the fuel inside the filler flap or on the cap, so check it on your first fill in a motor you do not know.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a household with one of each.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, yet it works.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away and keep your mind on the pump.
- Add-on devices exist for cars without one, and some diesels come with a filler that will not take a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- Noticing it mid-fill? Stop at once. A thinner mixture follows from less petrol inside the tank, but the next stage remains the same: do not fire it up.
Elstead: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. Still on the forecourt, at Esso or anywhere else? Ask the attendants to help you push the vehicle clear of the petrol pump. Then phone 0333 366 0103 and tell us what went in, about how much, and if it's run.
If it was AdBlue instead of petrol, say so. That is a separate problem — corrosion and deposits rather than lost lubrication — and it has its own page for Elstead.
One petrol in a diesel job around Elstead costs more than another. Why?
There is no fair single price for this, since the four scenarios above are four separate tasks. What moves your cost is chiefly which of them you are in. The proportion matters next, meaning how much of your tank is petrol, and then the position of the car and whether getting to it is safe for a technician.
Before any quote, not after, we ask three queries: your fuel that went in, the volume, and if it's run. That's why. A range becomes a straight figure once those answers are in.
About Elstead, for a moment
Elstead is a village in Surrey, situated on the banks of the River Wey at an elevation of around 53 metres. Elstead has a mix of housing types, but semi-detached homes are particularly prevalent, and the village is located near to Pot Common and Charleshill. Elstead is also relatively close to Gatwick, and its residents are around 33.8 miles from London. Elstead remains a small, rural community with a population of approximately 929 people.
Elstead and Surrey: where our fuel drain cover reaches
Elstead sits in the GU postcode area, and our vans that answer petrol in diesel jobs there work the locations around it as well — Pot Common, Charleshill and Gatwick among them. The vehicle does not need to come to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the pump in Elstead, right now?
The best place there is, then — that is where you are. Switched off it stays; then phone.