How Worried Should You Be? Petrol in a Diesel Car in Scone
Likely less than you already are — provided no one has started it. "Have I wrecked it?" is the first question everyone around Scone asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing till it is dragged through the system — by ignition priming, by the starter, or by driving. To leave the car like that, ring Petrol in Diesel and leave your engine alone. What petrol really does to a diesel, how to judge how far it's travelled, and how to stop it from happening again: that is the rest of this page.
What petrol in a diesel does to the engine
Passing through a motor, diesel is doing two jobs at once. It lubricates to begin with, and only then does it burn. Your high-pressure pump and the fuel injectors are designed to very fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump running on the mixture wearing itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
Seen together, they show what shape the problem has. Not contact but circulation is what causes the damage. Any tank with petrol in it is a fuel fault. Once the pump has been running on that petrol, a mechanical issue has started: anything shed by a pump that is grinding travels downstream to your injectors with the fuel.
How bad is petrol in a diesel? Four situations our engineers see in Scone
Fuelled, and never started: nothing beats it. The petrol is in your tank and just the tank, and the task is a drain and a flush where your car stands. This is the one situation that can only really take place at a forecourt, since anywhere else the vehicle has been driven to get there.
The ignition switched on, or a brief start. With your system primed, your lines and filter now hold petrol that came from the tank. Still generally straightforward: drain, flush, and your filter seen to.
The pump now worked a couple of miles on diluted fuel — that is what driving it does. The work is that tank, the fuel lines, the filter and fresh fuel through the entire system, and how hard the car was driven matters as much as how far. A school run to the local primary school is one thing. A run as far as Perth, under 3 miles away, is a very different task. So is any miles on the M90, under 3 miles from Scone, where your engine has been running hard throughout.
Driven until it complained. Clattering, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer runs like diesel. Whether it is the verge on Angus Road, a lay-by or a side street, stop there and leave it. The fuel drain and flush still come first, and they take care of it: if a vehicle is pulled over soon, long-term damage is very rare.
Petrol in a diesel myths Scone people hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A fuller tank of the same mixture is all it gives, since topping up removes nothing. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. At higher pressure, through smaller components: that's how a newer diesel moves its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that catches drivers. A petrol motor fed diesel normally will not run, so the motorist stops and the harm stops with them. Feed petrol to a diesel and it usually fires up, ticks over and drives away like nothing has happened — all while its pump wears. Being able to run isn't proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different issue. It does not put back what petrol has thinned, and the petrol is still in your tank afterwards.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in your filter and lines, waiting to go right back through your pump at your next start. Draining petrol into a can at the roadside is also truly hazardous.
How does petrol in a diesel take place?
It's seldom carelessness, and no one does it on purpose. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol vehicle at all. So the slip runs one way.
The moment habit stops matching your car is the moment it takes place. A new vehicle, a hire car or a courtesy car. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Fuelling up in a rush en route to Perth, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. Throw in a back seat full of kids, a phone call or rain, and the hand takes over.
Next time you fill up in Scone: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use.
- Label 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 vehicle, say "diesel" out loud. Silly, perhaps, but it does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, so the phone goes 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 exist for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- As soon as you notice, stop: less petrol in the tank makes a thinner mix. What to do next doesn't change, though — still don't start the vehicle.
Already put petrol in a diesel in Scone?
Then the order of things is short. Do not turn the ignition on, and don't start it. If you are still on the forecourt — Tesco or anywhere else — ask the attendants to help you push the vehicle clear of the petrol pump. Phone 0333 366 0103 next, with three facts — the fuel, the approximate quantity, and if it's run.
If it was AdBlue and not petrol, say so. That's a separate issue — corrosion and deposits and not lost lubrication — and it has its own page for Scone.
Why one petrol in a diesel task around Scone costs more than another
Four different tasks sit behind the four situations above — which is why there is no fair single price. The scenario itself does most of the work of moving the cost. Beyond that it is the share — how much petrol was put in against how much your tank holds — and after that where the vehicle is and whether a technician can reach it safely.
Ahead of any quote, not after, we ask three queries: your fuel that went in, the amount, and if it has run. That is why. Their replies are what turn a range into one firm number.
About Scone and its setting
Scone is a village situated on the River Tay in Perth and Kinross, Scotland, with a mix of old and new buildings, including many detached homes. Scone lies close to the city of Perth, which is about 2 miles away, and is near other small communities like Gannochy and Old Scone. Scone has a population of around 2127 people and is located at an elevation of 55 metres above sea level. Scone is also relatively distant from major English cities, with London being approximately 364 miles away.
Fuel drain cover across Perth and Kinross, Scone included
Petrol in diesel call-outs in Scone — part of the PH postcode area — go to teams that likewise cover the locations round it, Gannochy, Old Scone and Quarrymill among them. The car doesn't need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Scone and still at the petrol pump?
Then, you could not be in a better place. Keep the car switched off, then ring.