How Worried Should You Be? Petrol in a Diesel Car in New Barn
If it has not been started, you can worry far less than you likely are. Petrol resting in a diesel tank does nothing to the motor till something draws it through your fuel system — the ignition priming your pump, your starter, or the drive on its own. So the fair answer to the first question everyone in New Barn asks, "have I ruined it?", is normally no. To leave the car that way, phone Petrol in Diesel then leave your motor alone. Below, you will find 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
Passing through a motor, diesel does two jobs at the same time. Lubricating comes before burning; it does both. Built to extremely fine clearances, the injectors and your pump depend on the diesel flowing through them to stop their surfaces wearing against one another.
Badly at the first, not at all at the second: that is petrol. The rattling comes from petrol being made not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection the system depends on, and any pump working on such a mix is wearing itself.
Seen together, they make clear the shape the problem has. Contact doesn't do the harm — circulation does. Petrol in the tank is a fuel fault. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
How serious is petrol in a diesel? Four situations our engineers see around New Barn
The best case there can be: filled up, never started. Just the tank has petrol in it, and so the job is clearing your tank and flushing the fuel system where the vehicle stands. This scenario can only really take place on a forecourt: anywhere else, your car got there by being driven.
A moment's running, or just the ignition on. Petrol has come out of that tank and reached the filter and the fuel lines, since your system has been bled. That's usually still a simple task — a drain, a flush, and the filter seen to.
A couple of miles driven, and the pump has spent each of them running on weakened fuel. Tank, lines, filter, then clean fuel put through the whole system: that's the work, and the way your car was driven counts as much as the distance. On the school run to Langafel Church of England Voluntary Controlled Primary School, the mileage is small. Getting as far as Southend-on-Sea, under 25 miles away, makes a very different job — as does any miles on the M20, under 5 miles from New Barn, with the motor running hard the whole time.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. That's the engine telling you its fuel has stopped acting like diesel. Pull up wherever you are — the verge on New Barn Road, a lay-by, a side street — and leave the car there. What comes first is still the drain and flush-through, and that sorts it out, with permanent damage very unusual when a vehicle is pulled over quickly.
What New Barn motorists get told about petrol in a diesel — and the stories in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, however much that guidance assumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through smaller parts: that's how a current diesel handles its fuel, so the protection matters for more, not less.
"It starts, it drives, so there is no harm" — the myth that catches more drivers than any other. Any petrol engine fed diesel normally will not run, so the driver stops and the harm stops with them. While the pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct problem. The petrol is still in that tank after that, and what it has diluted is not put back.
Myth: "Drain the tank yourself and you are sorted." Once the motor has run, some of that petrol is no longer inside the tank: it is in the filter and your lines, and it goes right back through your pump at the next start. Also, a can of petrol drained by the kerbside is genuinely dangerous.
How does petrol in a diesel happen?
It is seldom carelessness, and no one 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 mostly won't go into a petrol motor at all. The forecourt makes it simple, and the mistake runs one way.
The moment routine stops matching the car is the moment it occurs. Courtesy car, hire car, or a car that is new. One petrol and one diesel on the drive of the same household. A forecourt you know, but with its pumps laid out differently. Rushing for a train outside Longfield and filling up en route. Years of petrol vehicles behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of children, and the hand does what it has always done.
How to prevent petrol in a diesel on your next fill-up in New Barn
- Green for unleaded and black for diesel is usual in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- In a car you do not know, look inside the flap over the filler or at the cap before your first fill: many vehicles state the fuel type there.
- Label the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that won't accept a petrol nozzle. Useful — but a safety net only, never a reason to stop checking the label.
- Noticing it mid-fill? Stop there and then. A weaker mixture follows from less petrol inside the tank, but the next step stays the same: do not crank it.
New Barn: already put petrol in a diesel?
Short and simple, then, is the order of things. Starting it is out, and so is switching on your ignition. If you are still on the forecourt — Shell or anywhere else — ask the staff to help you roll the car away from the pump. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it has been run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — New Barn has a page just for it.
One petrol in a diesel task in New Barn costs more than another. Why?
Four different tasks sit behind the four scenarios above — which is why there's no honest single price. The scenario itself does most of the work of moving your cost. Where the vehicle is matters too, and whether a technician can safely get to it, after the share of petrol to what that tank holds.
That's why our engineers ask three questions before costing instead of after: what went in, how much, and whether it's run. Those answers change a range into a straight figure.
About New Barn and its setting
New Barn is a village in Kent, situated inland at an elevation of 99 metres, and is located near Longfield Hill and the villages of Longfield and Hartley. New Barn has a population of around 2088 people and is characterized by predominantly detached housing. New Barn is within commuting distance of London, being approximately 21 miles from the city, and is also close to the nearest city of Southend-on-Sea, which is about 19 miles away.
Fuel drain cover around New Barn and across Kent
Petrol in diesel call-outs in New Barn — part of the DA postcode area — go to vans that also cover the locations about it, Longfield Hill, Longfield and Hartley among them. The car does not need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In New Barn and still at the petrol pump?
Then, you couldn't be in a better position. Call, and keep it switched off.