How Worried Should You Be? Petrol in a Diesel Car in Pen-y-Lan
Unstarted? Then less worried than you likely are. Until the ignition primes the pump, the starter turns, or your vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which means the truthful reply to that first Pen-y-Lan query — "have I wrecked it?" — usually no. Leave the engine off and ring Petrol in Diesel — that keeps it like that. Below, this page sets out what petrol really does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel does
Diesel does two jobs on its way through a motor. It lubricates first, and only then does it burn. Very fine gaps are built into the injectors and the high-pressure fuel pump, and just your diesel flowing through stops those surfaces grinding together.
Of those two jobs, petrol handles the first poorly and the second never. The clattering comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system hinges on, and any pump running on such a blend is wearing itself.
Put those together and the shape of the trouble is plain. Not contact but movement is what does the damage. All a tank with petrol in it amounts to is a fuel issue. 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 your fuel to the fuel injectors downstream.
How serious is petrol in a diesel? Four scenarios we see around Pen-y-Lan
Fuelled, and never started: no case is better. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol kept in the tank alone, it's drained and cleaned on the spot, and nothing more is needed.
A brief spell of running, or just your ignition on. Petrol has come out of the tank and reached the fuel filter and the fuel lines, because the system has been primed. Normally nothing more than clearing, flushing and seeing to the fuel filter, and so still simple.
Those few miles on the road were the pump running on fuel weakened by petrol throughout. Tank, lines, filter, then fresh fuel put through the whole circuit: that's the work, and the way your car was driven matters as much as the distance. Driving the kids to the local primary school is one sort of trip. Driving as far as Swansea, under 10 miles away, makes a very different job — as does any mileage on the M4, under 5 miles from Pen-y-Lan, with your engine working hard the whole time.
Driven on till it complained — rattling, smoke, a ragged idle, a soft throttle. The fuel isn't acting like diesel any more, and the engine is saying so. Stop wherever you are — the verge on Pen-y-Lan, a lay-by, a side street — and leave the car where it is. A vehicle pulled over early very seldom has long-term damage, since the fuel drain and the flush-through, which still come first, take care of it.
Pen-y-Lan people and the petrol in a diesel myths they hear
Myth: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mix is all it gives, because topping up takes out nothing. A diesel fuel system does not tolerate petrol by percentage in the way that advice presumes.
Myth: a modern diesel copes with a bit of petrol. If anything, the reverse. At higher pressure, through more precise parts: that is how a newer diesel handles its fuel, and so the protection matters for more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally leaves a motor that won't run: the driver stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Running isn't the same as fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, supposed for another problem. That petrol is still inside your tank after that, and what it has thinned isn't put back.
Myth: "Drain the tank yourself and you're sorted." After the motor has run, some of that petrol is no longer in that tank: it is in the filter and the fuel lines, and it goes straight back through the pump on your next start. Also, a can of petrol drained by the roadside is genuinely dangerous.
How does petrol in a diesel take place?
Nobody does it on purpose, and it is rarely carelessness. A diesel nozzle generally won't go into a petrol motor, yet the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and just in one direction.
When routine and the car stop matching, it occurs. Any motor that is new to you — a hire car, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the driveway. The pumps in a different order on a familiar forecourt. Rushing for a train at Bynea and fuelling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it happens. Throw in 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 in Pen-y-Lan
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the pump's label; the colour is only a clue.
- The first fill in an unfamiliar motor is the time to check your filler flap — inside it, or on the cap, plenty of motors state which fuel they take.
- One of each in the home? Mark the key to your diesel — a bright fob, a sticker — since intending to remember is not enough.
- Before the nozzle leaves the pump the first time you fill a hired or new car, say "diesel" aloud. Daft, perhaps, but it does the trick.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop reading the petrol pump.
- Stop the moment you notice. Less petrol inside that tank makes a thinner mixture. It does not change what to do next, which is still not to crank it.
Put petrol in a diesel in Pen-y-Lan already?
Short and simple, then, is the order of things. Never fire it up, and don't turn your ignition on. Ask the attendants to help you roll it clear of the pump if you are still on the forecourt, whether that is Tesco or anywhere else. Then ring 0333 366 0103 and tell us what went in, about how much, and if it has run.
Say so if it was AdBlue rather than petrol: it's a different problem, with its own page for Pen-y-Lan, because AdBlue brings corrosion and deposits instead of lost protection.
Why one petrol in a diesel task around Pen-y-Lan costs more than another
There is no honest single quote for this, since the four situations above are four different tasks. The scenario itself does most of the work of moving the cost. Beyond that it's the share — 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.
What was put in, how much, and if it has run — three questions our engineers ask before pricing, not after, for exactly that reason. A range becomes a straight figure once the replies are in.
About Pen-y-Lan, for a moment
Pen-y-Lan is a suburban area located on the coast of Swansea, with an elevation of around 50 metres above sea level. Pen-y-Lan sits approximately 7 miles from the city centre of Swansea, within commuting distance of the city's amenities. Pen-y-Lan is characterized by its predominantly semi-detached housing stock, reflecting the area's development as a residential suburb. Pen-y-Lan is situated near other local places, including Parc-hendy and Blue Anchor.
Across Swansea and around Pen-y-Lan: fuel drain cover
Our teams answering petrol in diesel jobs around Pen-y-Lan, in the SA postcode area, also work the places around it, Parc-hendy, Blue Anchor and Pen-clawdd included. The car does not need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In Pen-y-Lan and still at the pump?
Then you're in the best position there is. Ring, and leave it switched off.