Rosewell: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided no one has started the car. "Have I ruined it?" is the first thing anyone around Rosewell asks, and the truthful answer is normally no, since petrol left in a diesel tank harms nothing until it's drawn through the fuel system — by ignition priming, by the starter, or by driving. To leave the vehicle that way, ring Petrol in Diesel then leave the engine switched off. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and ways to make sure you never repeat it.
The motor and petrol in a diesel: what happens
Two tasks fall to diesel on its journey round a motor. It combusts, and before it ignites it lubricates. What stops the surfaces inside the high-pressure pump and the injectors from wearing down against each other is your diesel flowing through them — they are made to very fine gaps.
Petrol handles the first task badly and the second not at all. It is thinner than diesel and takes away the protection your fuel system rests on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the rattling comes from.
Put these together and the shape of the issue is plain. Contact doesn't do the harm — movement does. Where that petrol is only in your tank, it is an issue of fuel, nothing more. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Petrol in a diesel around Rosewell: how bad is it? Four cases
Filled up, not once started. The best case there is. Only the tank has petrol in it, and so the task is draining your tank and cleaning the system where the vehicle sits. This scenario can only truly take place on a forecourt: anywhere else, the car got there by being driven.
A moment's running, or merely the ignition on. Once primed, your system has drawn petrol out of your tank as far as the filter and the lines. Drain, flush, deal with your filter: still normally easy.
The pump has spent a couple of miles on diluted fuel — that's what driving it meant. How hard the vehicle was driven matters as much as how far, and the work covers the tank, your lines, the filter and clean fuel through the entire circuit. On the school run to the local primary school, the distance is small. Any miles on the M8, under 10 miles from Rosewell, means the engine working hard throughout, and a run to Edinburgh, under 10 miles away, is a very different job as well.
Driven on until it complained — knocking, smoke, a ragged idle, a dead throttle. The motor is telling you your fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Louisa Square, a lay-by, a side street — and leave it there. Lasting damage is very uncommon if a vehicle is stopped soon, and the drain and flush-through that still come first take care of it.
Rosewell people and that petrol in a diesel stories they hear
Myth: topping up to full with diesel makes it fine. It does not. Topping up removes nothing; it gives you a bigger tank of the same mix. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse holds. Myth: "A modern diesel can cope with a bit of petrol." Smaller components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication count more, not less.
One myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it normally will not run, and so the motorist stops — and the damage stops with them. Nothing seems 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 isn't the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate problem. None of what petrol weakened is put back by it — and later, that tank still contains that petrol.
Myth: "Drain your tank yourself and you are sorted." Once the engine has run, some of the petrol is no longer in your tank: it is in your filter and the fuel lines, and it goes straight back through the pump on the next start. It is also truly dangerous to drain petrol into a can by the roadside.
Why petrol in a diesel takes place at all
It's seldom carelessness, and nobody does it on purpose. A diesel nozzle generally won't go into a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and only in that direction.
It occurs when habit and the vehicle stop matching. Courtesy car, hire car, or a vehicle that's new. One petrol and one diesel on the driveway of the same household. A forecourt you know, only with its pumps arranged differently. A rushed fill en route to Newtongrange with a train to catch. The first fill-up in a diesel Renault Clio after years of driving petrol is exactly the moment it takes place. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up in Rosewell
- The label is what counts, so check the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Inspect the filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on the first fill in any vehicle you don't know.
- One of each in the home? Label your key to your diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It sounds daft and it works.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to block a petrol nozzle, and aftermarket devices exist for the rest. Count it as a backstop, then keep checking the petrol pump.
- Less petrol makes a thinner mix, so stop the moment you notice — though remembering that the next stage is unchanged. It's still not to crank it.
Already put petrol in a diesel in Rosewell?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition switched off as well. The staff at the forecourt — whether at Asda itself or wherever you filled up — will usually help push it away from the petrol pump if you ask. Call 0333 366 0103 next, with three facts — your fuel, the rough quantity, and whether it's run.
Say so if it was AdBlue rather than petrol: it is a different fault, with its own page for Rosewell, since AdBlue brings corrosion and deposits rather than lost lubrication.
One petrol in a diesel job in Rosewell costs more than another. Why?
There's no honest single price for this, since the four situations above are four different tasks. Which of them you are in is mostly what shifts your cost. After that it's the proportion — how much petrol got in against how much your tank takes — and then where the car is and whether a technician can get to it safely.
Before any quote, not after, we ask three queries: your fuel that was put in, the quantity, and whether it has run. That's why. A range becomes a straight figure when those answers are in.
About Rosewell itself
Rosewell is a village situated on the riverside in Midlothian, with a mix of terraced housing and other residential properties, lying approximately 7 miles southeast of Edinburgh. Rosewell sits at an elevation of around 151 metres, near the villages of Roslin, Polton, and Poltonhall. Rosewell has a population of around 1479 people, and its location near Edinburgh makes it a commuter base for the city. Rosewell is also relatively distant from London, at around 324 miles away.
Across Midlothian and in Rosewell: fuel drain cover
Rosewell sits in the EH postcode area, and the vans that answer petrol in diesel jobs there work the locations near it as well — Roslin, Polton and Poltonhall among them. The car does not need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Rosewell: still at the pump?
Nothing beats it: that is where you are. Switched off it stays; then ring.