Should You Worry? Petrol in a Diesel Car in Roseburn
Less than you likely are, if it has not been started. Petrol sitting in a diesel tank does nothing to the motor until something pulls it through the system — the ignition priming your pump, the starter, or driving itself. So the honest answer to the first question anyone around Roseburn asks, "have I ruined it?", is normally no. Petrol in Diesel is who to call, with your engine kept off, so it stays that way. Further down, this page sets out what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what happens
On its way through an engine, diesel does two tasks. It burns, and before it ignites it protects. What stops the surfaces inside the high-pressure fuel pump and your injectors from wearing down against one another is your diesel passing through them — they are designed to very fine clearances.
The second job petrol does not do at all, and the first it does poorly. A pump running on a petrol mix is wearing itself out, since petrol is thinner than diesel and takes away the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any rattling starts.
Seen together, they show what shape the problem has. Contact doesn't do the damage — circulation does. Any tank with petrol in it is a fuel fault. The beginning of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
How bad is petrol in a diesel? Four situations our technicians see in Roseburn
Fuelled but not once started — as good as it gets. That petrol is inside your tank and just your tank, and the task is a drain and a flush where your car sits. This is the one situation that can only truly occur on a forecourt, because anywhere else your car has been driven to get there.
Your ignition switched on, or a brief start. With the fuel system primed, the fuel lines and filter already contain petrol that came from the tank. Still generally straightforward: drain, flush, and your filter dealt with.
Driven a few miles. Now your pump has spent those miles labouring on thinned fuel. Tank, lines, filter, then fresh fuel put through the entire system: that is this work, and the way your car was driven counts as much as the miles. On the school run to the local primary school, the mileage is short. A run as far as Edinburgh, under 3 miles away, is a very different job. So is any mileage on the M8, under 5 miles from Roseburn, where the motor has been working hard the whole time.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. That is your motor telling you its fuel has stopped behaving like diesel. Stop wherever you are — the verge on Roseburn Avenue, a lay-by, a side street — then leave it where it is. A vehicle stopped quickly very seldom has lasting damage, since the fuel drain and the flush, which still come first, sort it out.
Roseburn motorists and the petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up removes nothing; it gives you a fuller tank of the same mixture. The assumption behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. A current diesel runs its fuel through more precise components at higher pressure, which makes the protection count more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most people than any other. A petrol engine fed diesel normally won't run, and so the driver stops and the harm stops with them. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, while the pump wears. Running is not the same as fine.
Not so: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another issue. None of what petrol thinned is put back by it — and later, your tank still contains that petrol.
If the engine has run, part of the petrol sits in the fuel filter and the fuel lines, not that tank — and your next start sends it right back through the pump. So the myth "drain the tank yourself and you're sorted" does not stand up. Besides, petrol drained into a can by the road is truly hazardous.
Petrol in a diesel: how does it occur?
It's seldom carelessness, and nobody 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, while a diesel nozzle mostly will not go into a petrol vehicle at all. So the mistake runs one way.
Routine and the car getting out of step is how it occurs. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. Your ordinary forecourt, its pumps suddenly in a different order. Fuelling up in a rush on the way to Haymarket, with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist used to petrol: exactly when it occurs. Your hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Next time you fill up in Roseburn: preventing petrol in a diesel
- The label is what counts, so read the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- In a motor you do not know, look inside the flap over the filler or at the cap before your first fill: many motors print the fuel there.
- One of each in the house? Label the key to your diesel — a bright fob, a sticker — because meaning to remember is not enough.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Tuck your phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Noticing it mid-fill? Stop at once. A weaker blend follows from less petrol inside the tank, yet your next step stays the same: do not start the vehicle.
Put petrol in a diesel around Roseburn already?
In that case, there is only a short order of things. Do not fire it up, and don't turn your ignition on. Ask the staff to help you push it away from the petrol pump if you are still on the forecourt, whether that is Sainsbury's or anywhere else. Then ring 0333 366 0103 and tell us what went in, about how much, and if it's run.
If it was AdBlue instead of petrol, say so. That's a separate issue — corrosion and deposits and not lost lubrication — and it has its own page for Roseburn.
Why one petrol in a diesel task around Roseburn costs more than another
Four separate tasks sit behind the four scenarios above — which is why there is no fair single price. Which of them you are in is mostly what moves the cost. Next it's the ratio — how much petrol was put in against how much that tank takes — and then where your car is and whether our van can get to it safely.
What went in, how much, and whether it's run — three questions we ask before quoting, not after, for precisely that reason. A range turns into a straight figure when the replies are in.
About Roseburn itself
Roseburn is a suburban area in the City of Edinburgh, situated approximately 2 miles west of Edinburgh's city centre. Roseburn occupies a coastal setting, with its elevation at around 45 metres above sea level, and is characterised by predominantly flat-type housing. Roseburn is close to nearby places such as Gorgie, Murrayfield, and Saughtonhall, and is home to a population of around 7259 residents.
Across City of Edinburgh and in Roseburn: fuel drain cover
Roseburn sits in the EH postcode area, and the vans that answer petrol in diesel call-outs there work the spots near it as well — Gorgie, Murrayfield and Saughtonhall among them. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians work, and the vehicle does not need to come to us.
Roseburn: still at the petrol pump?
Then you are in the best place there is. Keep it off. Ring.