How Worried Should You Be? Petrol in a Diesel Car in Dundee
Likely less than you already are — provided nobody has started it. "Have I wrecked it?" is the first question everyone in Dundee asks, and the truthful answer is generally no, because petrol left in a diesel tank harms nothing till it's dragged through the system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to ring, with your engine kept off, and so it remains that way. The remainder of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
Diesel does two tasks on its way through an engine. Before it ignites, it lubricates — then it combusts. Designed to very fine tolerances, the fuel injectors and your pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Petrol handles 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 running on the blend to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
Combined, those leave the shape of the problem plain. The harm is done by movement, not by contact. Petrol in a tank is a fuel fault. After your pump has been running on that petrol, a mechanical problem has begun: anything shed by a pump that's grinding travels downstream to your injectors with the fuel.
Dundee, petrol in a diesel: four situations, from mild to significant
Filled up, and not started: nothing beats it. Only that tank has petrol in it, and so the task is emptying the tank and rinsing the system where your car stands. This situation can only really take place on a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or just your ignition on. The fuel system has been primed, and so petrol has left that tank and reached the filter and the lines. Drain, flush, see to your filter: still usually easy.
Driven a few miles. Now your pump has spent those miles working on thinned fuel. Tank, lines, filter, then fresh fuel run through the entire circuit: that's the work, and the way your car was driven counts as much as the distance. Short trips, like the school run to the local primary school, are one thing. Very different once more: a trip to Perth, under 25 miles away, or any miles on the M90, under 25 miles from Dundee, where your engine never stopped working hard.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. That's your motor telling you its fuel no longer is behaving like diesel. Whether it's the verge on Nethergate, a lay-by or a side road, stop where you are and leave it. What goes first is still the fuel drain and flush-through, and that takes care of it, with long-term damage very uncommon if a vehicle is stopped early.
Stories Dundee people hear about petrol in a diesel
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 mixture is all you get, because topping up takes out nothing. That advice supposes a diesel fuel system tolerates petrol by percentage. It does not.
If anything, the opposite is true. Myth: "A modern diesel can cope with a bit of petrol." Smaller parts and higher pressure are how a modern diesel runs its fuel, and that makes the protection matter more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most people than any other. The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump grinds. Running does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct problem. None of what petrol thinned gets put back by it — and afterwards, the tank still holds the petrol.
The next start draws petrol back round your pump out of your lines and the filter, where some of that sits once the engine has been run. That is why draining your tank yourself doesn't leave you sorted — a myth. It is also truly risky to drain petrol into a can by the kerbside.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. 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 vehicle. That is how the forecourt makes it easy.
When routine and the vehicle stop matching, it takes place. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Filling up in a rush en route to the nearest station, with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
How to avoid petrol in a diesel at your next fill-up around Dundee
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the petrol pump's label; the colour is just a clue.
- Many motors state the fuel type inside the filler flap or on the cap, and so check it on the first fill in any vehicle you don't know.
- One of each in the house? Label your key to the diesel — a bright fob, a sticker — because intending to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds silly. It works.
- While you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that won't take a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in the tank means a weaker blend. What to do next does not change, though — still don't crank it.
Put petrol in a diesel in Dundee already?
Short and simple, then, is the order of things. Don't turn your ignition on, and don't fire it up. Still on the forecourt, at Tesco or anywhere else? Ask the staff to help you roll it clear of the pump. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it has been run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate problem — Dundee has a page all for it.
Why one petrol in a diesel task in Dundee costs more than another
Four separate jobs sit behind the four scenarios above — which is why there is no fair single price. The situation itself does most of the work of moving the cost. Next it is the ratio — how much petrol got in against how much your tank takes — and then where the vehicle is and whether a van can reach it safely.
Three queries come first, before quoting, rather than after — what was put in, how much, has it run — and this is the reason. Their answers are what change a range into one firm number.
About Dundee itself
Dundee is a significant urban centre situated in the eastern part of Scotland's Lowlands, where it meets the coast. Dundee is positioned on the northern shore of the Firth of Tay, a major estuary that opens out into the North Sea. The city is known for its coastal location and is a major part of the country's landscape. It is a notable city in Scotland, with a distinct character shaped by its setting.
Fuel drain cover across Dundee City, Dundee included
Dundee waits in the DD postcode area, and the teams that answer petrol in diesel call-outs there work the spots near it as well — Hilltown, Maryfield and Newport-on-Tay among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our engineers drain, and the car doesn't need to move to us.
Dundee: still at the petrol pump?
The best position there is, then — that is where you are. Phone, and keep it switched off.