Petrol in a Diesel Car in Green: How Worried Should You Be?
Likely less than you are now — provided nobody has started the vehicle. Everyone around Green begins with "have I ruined it?", and the honest answer is generally no: petrol left inside your tank of a diesel stays harmless until priming, cranking or driving pulls it into your fuel system. To keep it like that, call Petrol in Diesel then leave your motor alone. Below, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the engine?
Diesel does two jobs on its way through an engine. It combusts, and before it burns it lubricates. Extremely fine gaps are built into your injectors and your high-pressure pump, and only your diesel flowing through keeps their surfaces from grinding together.
The second job petrol doesn't do at all, and the first it does badly. It's thinner than diesel and takes away the protection your fuel system rests on, so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the rattling comes from.
Seen together, they show what shape the problem has. It's circulation that causes the harm, not contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors further on.
Green, petrol in a diesel: four situations, from mild to significant
Filled up, and never started: nothing beats it. Being on a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held in the tank alone, it is emptied and purged on the spot, and nothing more is needed.
A moment's running, or just the ignition on. Once primed, your system has drawn petrol from the tank as far as the filter and your lines. Still generally straightforward: drain, flush, and the filter sorted.
Those few miles on the road were your pump running on fuel thinned by petrol the whole way. Tank, lines, filter, then clean fuel run through the entire circuit: that's the work, and the way the car was driven matters as much as the distance. Driving the kids to the local primary school is one sort of trip. Any distance on the M4, under 50 miles from Green, means the motor working hard throughout, and a run to St Davids, under 25 miles away, makes a very different job as well.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. That's the engine telling you its fuel has stopped acting like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Green Meadow Avenue. A car stopped quickly very rarely has lasting damage, as the fuel drain and the flush, which still come first, deal with it.
Petrol in a diesel stories Green motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up removes nothing; it gives you a fuller tank of the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice supposes.
"Current diesels can handle a little petrol" — a myth, and closer to the opposite. A current diesel runs its fuel through smaller parts at higher pressure, which makes the protection count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there is no harm done." The driver of a petrol engine fed diesel normally has no choice but to stop, because it will not run, and the damage stops there. A diesel fed petrol normally starts, ticks over and drives away as though nothing has happened, while the 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. It doesn't put back what petrol has weakened, and that petrol is still inside your tank afterwards.
The next start draws petrol back round your pump out of your lines and your filter, where some of that ends up once your engine has been run. That is why draining the tank yourself does not sort it — a myth. Also, a can of petrol drained at the kerbside is truly risky.
How does petrol in a diesel happen?
No one does it on purpose, and it's rarely carelessness. One way only, since of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol motor. That is how the forecourt makes it straightforward.
The moment routine stops matching the car is the moment it takes place. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. Racing for a train at Pembroke and filling up en route. The first fill-up in a diesel Volkswagen Tiguan after years of driving petrol is precisely the moment it takes place. Add a back seat full of kids, a phone call or rain, and the hand takes over.
Green drivers: how to avoid petrol in a diesel next time
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- Plenty of vehicles state the fuel type inside your filler flap or on the cap, and so check it on your first fill in any motor you don't know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It sounds daft. It works.
- Mistakes like this are simple to make whilst your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to reject a petrol nozzle, and add-on devices are available for the rest. Treat it as a backstop, then keep checking the petrol pump.
- Less petrol means a thinner blend, so stop as soon as you realise — though remembering that the next step is unchanged. It's still not to fire it up.
Put petrol in a diesel around Green already?
Short and simple, then, is the order of things. Don't turn the ignition on, and don't start it. Ask the attendants to help you roll it away from the petrol pump if you are still on the forecourt, whether that is Tesco or anywhere else. Call 0333 366 0103 next, with three facts — your fuel, the approximate volume, and whether it has run.
Say so if it was AdBlue instead of petrol: it is a different problem, with its own page for Green, since AdBlue brings corrosion and deposits rather than lost protection.
What makes one Green petrol in a diesel job cost more than the next
The four situations above are four different tasks, so no single price for this would be fair. Chiefly, your cost moves with which one you are in. Where your car is matters too, and whether a van can safely get to it, after the share of petrol to what the tank takes.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and that is the reason. A range becomes a straight figure when those replies are in.
About Green
Green is a coastal suburban area in Pembrokeshire, situated near the cities of St Davids and Pembroke. Green sits at a low elevation of 18 metres, overlooking the coastline of Wales. Green is characterized by its semi-detached housing and is located near other suburban areas such as Golden Hill and Orange Gardens.
Fuel drain cover across Pembrokeshire, Green included
Golden Hill, Pembroke and Orange Gardens are among the locations near Green that the same vans work, answering petrol in diesel call-outs across Green's SA postcode area. Our engineers drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Green: still at the petrol pump?
Then you are in the best spot there is. Call, and leave it turned off.