Petrol in a Diesel Car in Southlow: How Worried Should You Be?
Less than you likely are, provided it hasn't been started. "Have I ruined it?" is the first question everyone around Southlow asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing till it is drawn through the fuel system — by ignition priming, by your starter, or by driving. Keep it like that: leave the motor off then phone Petrol in Diesel. The remainder of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what happens
Diesel does two jobs on its way through an engine. It protects to begin with, and only then does it burn. What keeps the surfaces inside the high-pressure fuel pump and the injectors from wearing against one another is the diesel flowing through them — they are built to extremely fine tolerances.
Of those two jobs, petrol handles the first badly and the second never. A pump running on a petrol mixture is wearing itself out, because petrol is thinner than diesel and takes away the protection your fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where the clattering comes.
Seen together, they show what shape the trouble has. Not contact but circulation is what does the harm. All a tank with petrol in it amounts to 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 travels on with the fuel to the fuel injectors further on.
Petrol in a diesel around Southlow: how bad is it? Four cases
Fuelled but not once started — as good as it gets. At a forecourt, and truly only there, the petrol is still limited to the tank — because anywhere else the vehicle was driven to reach it. The task is emptying and purging on the spot.
A brief spell of running, or just your ignition on. Petrol has left that tank and got to your filter and the lines, because the fuel system has been primed. That is normally still a straightforward job — a drain, a flush, and the fuel filter dealt with.
A couple of miles driven, and your pump has spent every one of them running on diluted fuel. The work is the tank, your lines, the fuel filter and clean fuel through the whole circuit, and how hard the car was driven counts as much as how far. On the school run to St John's CofE Primary School, the miles is small. Any distance on the M6, under 10 miles from Southlow, means the motor has worked hard throughout, and a run to Stoke-on-Trent, under 5 miles away, is a very different job too.
Driven till it protested. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel no longer is acting like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Leek Road. The fuel drain and flush-through still come first, and they sort it out: when a car is stopped quickly, long-term damage is very unusual.
Stories Southlow 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 will be." Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance presumes.
"Modern diesels can handle a little petrol" — a myth, and closer to the opposite. At higher pressure, through more precise parts: that is how a modern diesel handles its fuel, so the lubrication matters more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up more people than any other. Feed diesel to a petrol engine and it usually will not run, and so the motorist stops — and the damage stops with them. Feed petrol to a diesel and it generally fires up, idles and pulls away like nothing has happened — all the while its pump is wearing. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated fix for a distinct problem. That petrol is still inside your tank after that, and what it has weakened isn't put back.
Myth: "Drain the tank yourself and you're sorted." After your engine has run, some of the petrol is no longer in your tank: it is in your filter and your lines, and it goes right back through the pump on the next start. And, a can of petrol drained by the roadside is truly hazardous.
How petrol ends up: petrol in a diesel
It's rarely carelessness, and nobody does it on purpose. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it simple, and the mistake runs one way.
Routine and your car getting out of step is how it happens. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Racing for a train at Longton and fuelling up en route. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it occurs. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Preventing petrol in a diesel next time you fill up around Southlow
- Check the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what matters.
- The first fill in a strange vehicle is the time to check your filler flap — on it, or on the cap, plenty of motors state the fuel they take.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a home with one of each.
- 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 petrol pump.
- Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away.
- Add-on devices are available for cars without one, and some diesels come with a filler that will not accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- Less petrol means a thinner blend, and so stop the moment you notice — though remembering that the next stage is unchanged. It's still not to fire it up.
Put petrol in a diesel in Southlow already?
In that case, there's only a short order of things. Starting it is out, and so is switching on the ignition. If you're still at the forecourt — the nearest petrol station or anywhere else — ask the staff to help you roll the vehicle clear of the pump. What was put in, about how much, and if it's run: tell us that when you call 0333 366 0103.
If it was AdBlue instead of petrol, say so. That is a separate fault — corrosion and deposits instead of lost lubrication — and it has its own page for Southlow.
Why one petrol in a diesel job in Southlow costs more than another
Four different jobs lie behind the four situations above — which is why there's no honest single price. The situation itself does most of the work of moving your cost. The share matters next, meaning how much of that tank is petrol, and then the location of the vehicle and whether reaching it is safe for our van.
Before any quote, not after, we ask three queries: the fuel that was put in, the volume, and whether it has run. That is why. A range becomes a straight figure when those replies are in.
About Southlow, for a moment
Southlow is a small suburban area situated on the riverside in Staffordshire, with a mix of detached housing and a relatively low population of around 615 residents. Southlow sits at an elevation of 249 metres, overlooking the surrounding countryside and nearby settlements like Cellarhead and Withystakes. Southlow is located near the city of Stoke-on-Trent, approximately 4.6 miles away, and is part of the wider West Midlands region. Southlow has a peaceful setting, with the River Trent flowing nearby.
Southlow and Staffordshire: where our fuel drain cover runs
Cellarhead, Withystakes and Overmoor are among the places near Southlow that the same vans work, answering petrol in diesel jobs across Southlow's ST postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our technicians work, and your vehicle does not need to move to us.
Still at the petrol pump in Southlow?
In that case, you could not be in a better spot. Turned off it remains; then call.