Petrol in a Diesel Car in Kingsteps: How Worried Should You Be?
Not started? Then less worried than you likely feel. Petrol resting in a diesel tank does nothing to the motor till something draws it through your fuel system — the ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first question anyone in Kingsteps asks, "have I wrecked it?", is normally no. Petrol in Diesel is who to phone, with the engine left off, so it stays that way. Below, this page sets out what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the engine?
Two tasks fall to diesel on its route through a motor. It lubricates to begin with, and only then does it burn. What stops the surfaces inside the high-pressure pump and the injectors from grinding against each other is the diesel flowing through them — they are designed to extremely fine tolerances.
The second task petrol does not do at all, and the first it does poorly. It's thinner than diesel and strips away the lubrication the fuel system depends on, so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the clattering comes from.
The shape of the trouble is plain once you put those together. Not contact but circulation is what causes the harm. All a tank with petrol in it amounts to is a fuel issue. Whatever a worn pump sheds travels on, carried by your fuel, into your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical problem begins.
How serious is petrol in a diesel? Four scenarios we see around Kingsteps
The best case there can be: filled up, never started. On a forecourt, and truly only there, that petrol is still confined to that tank — since everywhere else the car was driven to get to it. The job is draining and flushing on the spot.
Your ignition turned on, or a short start. Once primed, the fuel system has drawn petrol out of your tank up to your filter and the fuel lines. That is normally still a straightforward task — a drain, a flush, and the filter seen to.
Those few miles driven were your pump labouring on fuel thinned by petrol throughout. Tank, lines, filter, then fresh fuel run through the whole circuit: that's the work, and the way the car was driven counts as much as the miles. The school run to the local primary school is one thing. A run as far as Inverness, under 25 miles away, is a very different job. So is any distance on the M90, over 50 miles from Kingsteps, where your engine has been working hard the whole time.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. The motor is telling you your fuel is no longer behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Lochloy Road. What goes first is still the drain and flush-through, and that deals with it, with permanent damage very uncommon if a vehicle is pulled over soon.
Stories Kingsteps 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 when you top up — that tank just holds more of the same mixture. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the opposite is true. Myth: "A newer diesel can cope with a bit of petrol." A modern diesel sends its fuel through more precise components at higher pressure, which makes the protection matter more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops there. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old fix for a different problem. What petrol has weakened remains diluted, and the petrol remains in your tank regardless.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in the fuel filter and lines, ready to go straight back through the pump at your next start. It is also genuinely hazardous to drain petrol into a can by the kerbside.
Petrol in a diesel: how does it take place?
It's seldom carelessness, and nobody does it on purpose. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol motor. That is how the forecourt makes it simple.
The moment habit stops matching the vehicle is the moment it takes place. Any vehicle that's new to you — hired, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A rushed fill on the way to Nairn with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. Throw in a back seat full of children, a phone call or rain, and habit wins.
Next time you fill up in Kingsteps: preventing petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is just a clue.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: many vehicles print the fuel type there.
- Mark the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" aloud. Silly, yes, yet it does the trick.
- Put the phone away. This is an easy mistake to make whilst you're thinking about something else.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- As soon as you realise, stop: less petrol in that tank makes a weaker blend. What to do next doesn't change, though — still do not start it.
Put petrol in a diesel around Kingsteps already?
Then, there's only a short order of things. Starting it is out, and so is turning on the ignition. Ask the attendants to help you roll it away from the pump if you're still on the forecourt, whether that is Sainsbury's or somewhere else. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it's been run.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Kingsteps, because AdBlue brings corrosion and deposits rather than lost lubrication.
What makes one Kingsteps petrol in a diesel job cost more than the next
The four situations above are four separate jobs, so no single quote for this would be honest. What moves the cost is chiefly which of them you're in. After that it is the share — how much petrol got in against how much the tank takes — and after that where the vehicle is and whether a technician can reach it safely.
Before any quote, not after, we ask three questions: your fuel that got in, the volume, and if it's run. That is why. Their answers are what turn a range into one firm number.
About Kingsteps and its setting
Kingsteps is a small coastal hamlet in the Highland council area, situated near the Moray Firth and close to the towns of Nairn and Auldearn. Kingsteps has a low elevation of around 12 metres, reflecting its coastal location. Kingsteps is characterized by its predominantly detached housing stock, with the nearby city of Inverness being a significant urban centre for the area.
Fuel drain cover around Kingsteps and across Highland
Our vans answering petrol in diesel jobs in Kingsteps, in the IV postcode area, equally work the spots near it, Fishertown, Nairn and Auldearn among them. Our technicians drain where your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Kingsteps: still at the petrol pump?
In that case, you couldn't be in a better spot. Ring, and keep it turned off.