How Worried Should You Be? Petrol in a Diesel Car in Brookhouse
Likely less than you already are — provided no one has started the car. Petrol resting in a diesel tank does nothing to the motor till something draws it through your fuel system — the ignition priming the pump, the starter, or driving itself. So the truthful answer to the first query anyone around Brookhouse asks, "have I ruined it?", is generally no. Keep it that way: leave your engine off and phone Petrol in Diesel. Below, you will find 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 the engine
On its way through a motor, diesel does two tasks. It protects to begin with, and only then does it burn. What stops the surfaces inside your high-pressure pump and the injectors from wearing against one another is your diesel flowing through them — they are built to extremely fine gaps.
The second job petrol does not do at all, and the first it does poorly. The knocking comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection the system hinges on, and any pump running on that mix is wearing itself.
Put these together and the shape of the problem is plain. It is movement that does the damage, not contact. Petrol in the tank is a fuel problem. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Four scenarios our technicians see in Brookhouse: how serious is petrol in a diesel?
Fuelled up, never started. The best case there is. The petrol is inside the tank and just your tank, and the task is a drain and a flush where the vehicle sits. This is the one scenario that can only really happen at a forecourt, since anywhere else the vehicle has been driven to get there.
A moment's running, or merely your ignition on. Petrol has come out of your tank and reached your filter and your lines, since your system has been primed. Still normally straightforward: drain, flush, and your filter sorted.
Some miles driven, and the pump has spent each of them running on weakened fuel. The work is the tank, your lines, your filter and fresh fuel through the entire system, and how hard the vehicle was driven matters as much as how far. On the school run to Caton St Paul's Church of England Primary School, the mileage is small. Any mileage on the Lune Valley Interchange, under 3 miles from Brookhouse, means your engine working hard throughout, and a run to Lancaster, under 5 miles away, makes a very different task as well.
Driven until it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is the motor reporting fuel that no longer behaves like diesel. Whether it's the verge on New Street, a lay-by or a side road, stop there then leave it. A car pulled over early very seldom has long-term damage, since the drain and the flush-through, which still come first, take care of it.
What Brookhouse people get told about petrol in a diesel — and the myths in it
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. That guidance presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. A modern diesel sends its fuel through finer parts at higher pressure, which makes the protection count more, not less.
"It starts, it drives, and so no harm done" — the myth that catches most people than any other. A petrol motor fed diesel usually will not run, so the driver stops and the harm stops with them. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, whilst the pump grinds. 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 issue. What petrol has weakened remains weakened, and the petrol remains inside that tank anyway.
The next start sends petrol back round the pump from the lines and the fuel filter, where some of that sits once the motor has been run. That's why a DIY tank drain does not sort it — a myth. Also, a can of petrol filled by the kerbside is truly dangerous.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and no one means to do it. A diesel nozzle generally won't go into a petrol car, yet the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake easy, and only in one direction.
When habit and the car stop matching, it takes place. Courtesy car, hire car, or a vehicle that's brand new. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Rushing for a train outside Lancaster and filling up en route. Years of petrol motors behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that's when. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
How to avoid petrol in a diesel at your next fill-up in Brookhouse
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is only a hint.
- Inspect the filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- One of each in the house? Label the key to your diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Before the nozzle comes off the pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Daft, perhaps, yet it works.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Add-on devices exist for motors 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.
- Spotting it halfway? Stop there and then. A thinner mix follows from less petrol inside the tank, yet the next step stays the same: do not start the car.
Brookhouse: already put petrol in a diesel?
Then, there's just a short order of things. Leave it unstarted, with your ignition switched off as well. The staff at the forecourt — whether at Station Garage itself or wherever you filled up — will usually help push it away from the pump if you ask. Ring 0333 366 0103 next, with three facts — your fuel, the rough amount, and whether it has run.
If it was AdBlue rather than petrol, say so. That's a separate issue — corrosion and deposits rather than lost lubrication — and it has its own page for Brookhouse.
One petrol in a diesel task around Brookhouse costs more than another. Why?
Four separate tasks lie behind the four situations above — which is why there's no fair single price. The scenario itself does most of the work of moving the cost. Two things come after that: the petrol that went in as a proportion of what the tank takes, then the spot the vehicle is in and whether a technician can get to it safely.
Three questions come first, before any quote, instead of after — what was put in, how much, has it run — and this is the reason. With the replies, there is a straight figure instead of a range.
About Brookhouse and its setting
Brookhouse is a suburban area in Lancashire, situated on the banks of a river at an elevation of 44 metres, approximately 4.5 miles from Lancaster. Brookhouse is characterized by its semi-detached housing stock and forms part of the wider Lancaster urban area, with nearby places including Caton Green and Caton. Brookhouse has a population of around 969 residents, who enjoy easy access to local amenities and the city of Lancaster.
Brookhouse and Lancashire: where our fuel drain cover runs
Brookhouse waits in the LA postcode area, and the vans that answer petrol in diesel calls there work the locations near it as well — Caton Green, Caton and Crossgill among them. Our engineers drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Brookhouse: still at the petrol pump?
The best spot there is, then — that is where you are. Keep the vehicle switched off, and ring.