Should You Worry? Petrol in a Diesel Car in Mumbles Hill
Far less than you likely are, if it has not been started. Everyone in Mumbles Hill starts with "have I wrecked it?", and the fair answer is normally no: petrol left inside that tank of a diesel remains harmless till priming, cranking or driving pulls it into your fuel system. To keep it like that, ring Petrol in Diesel then leave the motor alone. The remainder of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Inside your engine: what petrol in a diesel really does
Passing through a motor, diesel is doing two things at the same time. It burns, and before it combusts it lubricates. Extremely fine clearances go into the injectors and the high-pressure fuel pump, and only your diesel running through stops those surfaces grinding together.
Of those two tasks, petrol manages the first badly and the second never. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump on that mixture wearing itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Put these together and the shape of the trouble is clear. Not contact but circulation is what does the damage. All a tank with petrol in it amounts to is a fuel fault. Once your pump has been running on that petrol, a mechanical problem has begun: anything shed by a pump that's wearing travels onward to your injectors with the fuel.
How serious is petrol in a diesel? Four scenarios our technicians see around Mumbles Hill
Fuelled up, never started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol held inside your tank alone, it is drained and rinsed on the spot, and nothing more is needed.
Ignition on, or started for a second. Petrol has left the tank and reached the fuel filter and your lines, since the fuel system has been primed. Still usually simple: drain, flush, and the filter seen to.
A couple of miles driven, and your pump has spent each of them running on weakened fuel. Tank, lines, filter, then clean fuel put through the entire circuit: that's the work, and the way the vehicle was driven matters as much as the distance. On the school run to the local primary school, the mileage is short. A run as far as Swansea, under 5 miles away, is a very different task. So is any mileage on the M4, under 10 miles from Mumbles Hill, where the engine has been working hard the whole time.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. That is the engine telling you its fuel has stopped behaving like diesel. Stop wherever you are — the verge on Mumbles Road, a lay-by, a side street — and leave the vehicle there. The fuel drain and flush still go first, and they deal with it: when a car is pulled over early, permanent damage is very uncommon.
Stories Mumbles Hill drivers 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." Nothing comes out when you top up — that tank simply carries more of the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." At higher pressure, through more precise parts: that's how a current diesel handles its fuel, so the lubrication matters more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it generally will not run, so the driver stops — and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump wears. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. It does not put back what petrol has diluted, and that petrol is still inside your tank later on.
Myth: "Drain your tank yourself and you are sorted." Once the engine has been run, some of the petrol is no longer in that tank: it's in the fuel filter and your lines, and it goes straight back through the pump on your next start. And, a can of petrol drained by the roadside is truly risky.
How it happens: petrol in a diesel
It's seldom carelessness, and nobody does it on purpose. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it simple, and the slip runs one way.
It occurs when habit and the car stop matching. Courtesy car, hire car, or a vehicle that is brand new. Two vehicles on one driveway, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. Racing for a train at Swansea and fuelling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Mumbles Hill people: how to prevent petrol in a diesel next time
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- Check the filler flap. Plenty of cars state the fuel type inside the flap or on the cap. Look at it on the first fill in any vehicle you do not know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a house with one of each.
- It seems silly and it works: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Noticing it halfway? Stop there and then. A thinner mix follows from less petrol in that tank, but your next stage remains the same: do not start the vehicle.
Petrol already in a diesel around Mumbles Hill? Begin here
Then the order of things is brief. Starting it is out, and so is turning on your ignition. The attendants on the forecourt — whether at Newton Garage itself or wherever you filled up — will usually help push it away from the pump if you ask. What went in, roughly how much, and whether it's run: tell us that when you ring 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a different issue — Mumbles Hill has a page just for it.
One petrol in a diesel task around Mumbles Hill costs more than another. Why?
There is no honest single price for this, because the four situations above are four separate tasks. Which of them you are in is mostly what shifts your cost. Where the vehicle is counts too, and whether a technician can safely get to it, after the ratio of petrol to what the tank takes.
Three questions come first, before quoting, rather than after — what got in, how much, has it run — and that is the reason. With the answers, there is a straight figure instead of a range.
About Mumbles Hill itself
Mumbles Hill is a coastal locality in Swansea, situated approximately 4 miles southwest of the city centre, with The Knab, Limeslade, and Thistleboon nearby. Mumbles Hill rises to an elevation of 71 metres, offering views of the surrounding area. Mumbles Hill is characterised by its predominantly detached housing stock, reflecting its residential nature. Mumbles Hill is a small community, with a population of around 720 people.
Across Swansea and around Mumbles Hill: fuel drain cover
The teams answering petrol in diesel calls around Mumbles Hill, in the SA postcode area, equally work the locations near it, The Knab, Limeslade and Thistleboon included. A forecourt, a supermarket car park, a lay-by or your own drive are all spots we work, and your car does not need to come to us.
At the petrol pump around Mumbles Hill, still?
Then you are in the best position there can be. Keep it off. Call.