How Worried Should You Be? Petrol in a Diesel Car in Polbeth
Probably less than you already are — provided nobody has started it. Everyone around Polbeth begins with "have I ruined it?", and the fair answer is generally no: petrol left inside the tank of a diesel remains harmless till priming, cranking or driving draws it into the fuel system. Keep it that way: leave your engine off then ring Petrol in Diesel. What petrol actually does to a diesel, how to gauge how far it has travelled, and how to keep it from happening again: that's the rest of this page.
Inside the engine: what petrol in a diesel really does
On its way through an engine, diesel does two tasks. Before it ignites, it lubricates — then it combusts. What stops the surfaces inside your high-pressure pump and the fuel injectors from grinding against one another is the diesel flowing through them — they're built to very fine tolerances.
Petrol handles the first task badly and the second not at all. A pump running on a petrol mix is wearing itself out, because petrol is thinner than diesel and takes away the lubrication your fuel system relies on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any knocking comes.
Taken together, they make clear what shape the problem has. It's movement that does the harm, not contact. A tank with petrol in it is a fuel fault. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to your injectors further on.
Polbeth, petrol in a diesel: four situations, from mild to serious
Fuelled, and never started: nothing beats it. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol held in the tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
Ignition on, or started for a moment. Petrol has left that tank and reached the fuel filter and the lines, since your system has been bled. Drain, flush, see to your filter: still normally simple.
Driven a few miles. Now the pump has spent these miles working on weakened fuel. How hard the vehicle was driven counts as much as how far, and the work takes in that tank, your lines, the filter and fresh fuel through the whole system. Short trips, like the school run to the local primary school, are one matter. A run as far as Dunfermline, under 15 miles away, is a very different task. So is any mileage on the M8, under 3 miles from Polbeth, where your engine has been running hard throughout.
Driven on until it complained — clattering, smoke, a lumpy idle, a soft throttle. The fuel isn't behaving like diesel any more, and the engine is telling you. Leave it wherever it stops: a lay-by, a side street, the verge on Limefield Road. What goes first is still the drain and flush, and that sorts it out, with lasting damage very unusual when a vehicle is stopped soon.
Polbeth motorists and that petrol in a diesel stories they hear
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up removes nothing; it gives you a bigger tank of the same mix. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Not so: a current diesel copes with a bit of petrol. Rather, the opposite. A modern diesel sends its fuel through finer parts at higher pressure, which makes the protection count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there is no damage done." A petrol engine fed diesel usually won't run, and so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. Being able to run isn't proof of being fine.
An outdated workaround for a distinct problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol thinned is put back by it — and afterwards, the tank still contains the petrol.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol lies in the fuel filter and lines, waiting to go right back through your pump at your next start. Draining petrol into a can by the roadside is also truly risky.
How petrol ends up: petrol in a diesel
It is seldom carelessness, and no one does it on purpose. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol motor at all. So the error runs one way.
It happens when routine and your car stop matching. Any vehicle that's new to you — hired, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. A forecourt you know, but with its pumps arranged differently. Rushing for a train at West Calder and fuelling up en route. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it occurs. With rain, a call arriving, or a car full of children to deal with, your hand just does what it has always done.
Preventing petrol in a diesel next time you fill up around Polbeth
- Check the petrol 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.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of vehicles state the fuel there.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, in a house with one of each.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds silly. It works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels come with a filler built to block a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- As soon as you realise, stop: less petrol inside that tank means a weaker blend. What to do next does not change, though — still do not fire it up.
Polbeth: already put petrol in a diesel?
Then, there is just a short order of things. Do not start it, and don't turn the ignition on. Ask the attendants to help you push it clear of the pump if you are still on the forecourt, whether that is BP or anywhere else. Ring 0333 366 0103 next, with three facts — your fuel, the rough volume, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate problem — Polbeth has a page just for it.
One petrol in a diesel job around Polbeth costs more than another. Why?
The four scenarios above are four different jobs, so no single quote for this would be fair. The scenario itself does most of the work of moving your cost. Where the vehicle is matters too, and whether a van can safely get to it, after the ratio of petrol to what the tank takes.
That's why we ask three queries before quoting rather than after: what got in, how much, and if it has run. Those answers are what turn a range into one firm number.
About Polbeth, for a moment
Polbeth is a village situated on the riverside in West Lothian, with a mix of terraced housing and a population of around 1648 residents. Polbeth sits at an elevation of 163 metres, near the towns of Mossend, West Calder, and Bellsquarry. Polbeth is located approximately 14.9 miles from Dunfermline, the nearest city, and is part of the wider Scottish landscape. Polbeth's riverside setting provides a distinctive character to the village.
Fuel drain cover across West Lothian, Polbeth included
Our teams answering petrol in diesel jobs in Polbeth, in the EH postcode area, equally work the places near it, Mossend, West Calder and Bellsquarry included. Our engineers drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Polbeth: still at the petrol pump?
Then you're in the best spot there can be. Keep it off. Ring.