How Worried Should You Be? Petrol in a Diesel Car in New Farnley
If it hasn't been started, worry less than you likely are. Until your ignition primes the pump, the starter cranks, or your car is driven, petrol in a diesel tank just rests there and does no harm. Which means the truthful reply to the first New Farnley question — "have I ruined it?" — normally no. To leave the vehicle like that, phone Petrol in Diesel and leave your engine alone. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
Passing through an engine, diesel is doing two jobs at once. It protects to begin with, and after that does it burn. What keeps the surfaces inside your high-pressure pump and the injectors from wearing down against one another is the diesel flowing through them — they're built to very fine tolerances.
Of those two jobs, petrol manages the first poorly and the second not at all. A pump working on a petrol mixture is wearing itself out, since petrol is thinner than diesel and takes away the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any clattering starts.
The shape of the problem is plain when you put those together. It's movement that causes the harm, not contact. A tank with petrol in it is a fuel issue. Once the pump has been running on that petrol, a mechanical problem has begun: whatever is shed by a pump that is wearing travels onward to the fuel injectors with the fuel.
Four situations we see in New Farnley: how serious is petrol in a diesel?
Fuelled but not once started — the best it gets. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in your tank alone, it's drained and rinsed on the spot, and nothing more is needed.
A moment's running, or just the ignition on. Petrol has left that tank and got to the filter and the lines, because the fuel system has been bled. Drain, flush, see to the filter: still normally straightforward.
Your pump now worked a few miles on diluted fuel — that's what driving it meant. Tank, lines, filter, then fresh fuel run through the whole circuit: that is the work, and the way the car was driven counts as much as the distance. On the school run to Lawns Park Primary School, the miles is small. Driving as far as Leeds, under 5 miles away, makes a very different job — as does any mileage on the M621, under 3 miles from New Farnley, with the engine running hard all the way.
Driven until it protested. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel no longer is behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Ashdene. Lasting damage is very uncommon when a vehicle is pulled over quickly, and the fuel drain and flush-through that still go first sort it out.
What New Farnley motorists get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed when you top up — that tank simply holds more 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. Protection counts more on current diesels, not less, because their fuel runs through finer parts at higher pressure.
One myth that catches people off guard: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel normally has no choice but to stop, since it will not run, and the harm stops there. While the pump wears, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Being able to run isn't the same as being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, supposed for another fault. It does not put back what petrol has thinned, and that petrol is still in that tank after that.
Once your engine has run, part of the petrol sits in the filter and your lines, not your tank — and the next start pulls it right back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. Clearing petrol into a can by the roadside is also genuinely risky.
Petrol in a diesel: how does it occur?
Nobody does it on purpose, and it is rarely carelessness. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
The moment routine stops matching the vehicle is the moment it occurs. A new vehicle, a hire car or a courtesy car. Two cars on one drive, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. Fuelling up in a rush en route to Cottingley, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that is when. Add rain, a phone call or a back seat full of children, and the hand does what it has always done.
New Farnley drivers: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Check the filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on your first fill in any car you do not know.
- Mark your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It seems silly and it works.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away and keep your mind on the pump.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Spotting it mid-fill? Stop at once. A thinner blend results from less petrol in that tank, yet your next stage stays the same: do not fire it up.
Put petrol in a diesel in New Farnley already?
Then the order of things is brief. Starting it is out, and so is switching on your ignition. Yet at the forecourt, at BP or anywhere else? Ask the attendants to help you push the car away from the petrol pump. Ring 0333 366 0103 next, with three facts — your fuel, the rough quantity, and whether it has run.
If it was AdBlue rather than petrol, say so. That's a separate problem — corrosion and deposits rather than lost protection — and it has its own page for New Farnley.
New Farnley petrol in a diesel jobs: why one costs more than another
There is no honest single price for this, since the four scenarios above are four separate tasks. Chiefly, your cost moves with which situation you are in. After that it is the proportion — how much petrol went in against how much your tank takes — and then where your car is and whether a van can reach it safely.
That's why our engineers ask three queries before quoting rather than after: what was put in, how much, and whether it's run. A range becomes a straight figure when those replies are in.
About New Farnley
New Farnley is a suburban area in West Yorkshire, situated approximately 3.3 miles from Leeds and 168.9 miles from London. New Farnley sits at an elevation of 113 metres, surrounded by nearby places such as Low Moor Side, Roker Lane Bottom, and Upper Moor Side. New Farnley has a population of around 2189 people, predominantly residing in semi-detached housing.
Fuel drain cover in New Farnley and across West Yorkshire
Our teams answering petrol in diesel calls around New Farnley, in the LS postcode area, also work the places near it, Low Moor Side, Roker Lane Bottom and Upper Moor Side among them. The vehicle doesn't need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around New Farnley?
No position is better: that's where you now are. Keep the vehicle turned off, and ring.