Should You Worry? Petrol in a Diesel Car in Saltwood
Unstarted? Then less worried than you likely are. Petrol resting in a diesel tank does nothing to the motor until something pulls it through your fuel system — your ignition priming your pump, the starter, or the drive itself. So the truthful answer to the first question everyone in Saltwood asks, "have I ruined it?", is usually no. To keep it that way, phone Petrol in Diesel and leave the motor switched off. The remainder of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Inside the motor: what petrol in a diesel really does
Passing through a motor, diesel is doing two things at once. It lubricates to begin with, and only then does it burn. Very fine tolerances are built into your injectors and your high-pressure pump, and only your diesel running through keeps their surfaces from grinding together.
Petrol does the first job poorly and the second not at all. It's runnier than diesel and strips away the lubrication the system depends on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
Seen together, they make clear the shape the issue has. Contact does not do the harm — movement does. Where the petrol is only in your tank, it is a problem of fuel, nothing more. After your pump has been labouring on that petrol, a mechanical problem has started: anything shed by a pump that's grinding is carried downstream to the injectors with the fuel.
How bad is petrol in a diesel? Four situations our engineers see in Saltwood
Filled up, not once started. The best case there is. Only your tank has petrol in it, so the job is draining that tank and rinsing the fuel system where the car stands. This scenario can only really take place on a forecourt: anywhere else, your car got there by being driven.
Ignition on, or started for a moment. Once primed, the fuel system has drawn petrol out of that tank up to your filter and the lines. That is usually still a straightforward task — a drain, a flush, and the fuel filter seen to.
A couple of miles driven, and the pump has spent every one of them working on diluted fuel. Tank, lines, filter, then clean fuel run through the whole system: that's this work, and the way the car was driven counts as much as the miles. A school run to Saltwood CofE Primary School is one thing. Driving as far as Canterbury, under 15 miles away, makes a very different task — as does any miles on the M20, under a mile from Saltwood, with the motor running hard all the way.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. The fuel is not behaving like diesel any more, and your motor is saying so. Pull up where you are — on the verge on The Green, at the kerb, down a side road — and do not move it again. The drain and flush still come first, and they sort it out: when a car is stopped early, lasting damage is very unusual.
What Saltwood motorists get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed when you top up — that tank simply carries more of the same mixture. A diesel fuel system does not tolerate petrol by percentage in the way that guidance presumes.
Not so: a newer diesel copes with a bit of petrol. Rather, the opposite. A newer diesel sends its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most drivers than any other. Diesel in a petrol motor generally leaves a motor that will not run: the motorist stops, and so does the damage. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, whilst your pump wears. Fine and running are not the same at all.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. It does not put back what petrol has weakened, and the petrol is still in the tank after that.
Myth: "Drain your tank yourself and you are sorted." After the motor has been run, some of that petrol is no longer inside the tank: it's in the filter and the lines, and it goes right back through the pump on the next start. Clearing petrol into a can by the roadside is also really dangerous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. 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 car at all. The forecourt makes it simple, and the slip runs one way.
It takes place when routine and the car stop matching. Any car that's new to you — a hire car, on loan as a courtesy car, or just bought. Two cars on one driveway, one petrol, one diesel. Your normal forecourt, its pumps now in a different order. Racing for a train at Sandling and fuelling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a driver accustomed to petrol: exactly when it happens. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
Saltwood motorists: how to avoid petrol in a diesel next time
- Read the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on each forecourt. The label is what counts.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: many motors state the fuel type there.
- Mark your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new motor, say "diesel" aloud. Daft, yes, but it works.
- Whilst you are thinking about something else, this is an easy mistake to make — so put your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for motors without one. They are a safety net, not a reason to stop reading the petrol pump.
- Noticing it halfway? Stop there and then. A thinner mixture results from less petrol inside the tank, but the next step remains the same: do not start the car.
Put petrol in a diesel in Saltwood already?
The order of things is brief, then. Don't fire it up, and don't switch your ignition on. Still at the forecourt, at Esso or anywhere else? Ask the staff to help you roll the vehicle away from the petrol pump. What went in, roughly how much, and whether it has run: tell us that when you ring 0333 366 0103.
If it was AdBlue and not petrol, say so. That is a different fault — corrosion and deposits instead of lost protection — and it has its own page for Saltwood.
What makes one Saltwood petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four scenarios, four separate jobs. Mostly, your cost moves with which situation you're in. Beyond that it is the share — how much petrol went in against how much the tank holds — and then where your car is and whether a van can get to it safely.
Three questions come first, before quoting, rather than after — what got in, how much, has it run — and this is the reason. A range becomes a straight figure once those answers are in.
About Saltwood, for a moment
Saltwood is a village in Kent, situated on the English coast near the town of Hythe, with its residential area predominantly comprising detached houses. Saltwood sits at an elevation of 63 metres, overlooking the surrounding countryside and the English Channel. Saltwood is located near other settlements such as Orchard Valley and Sandling, and is within commuting distance of the city of Canterbury. Saltwood has a population of around 1231 residents, who enjoy its rural setting and proximity to the coast.
Fuel drain cover across Kent, Saltwood included
Petrol in diesel call-outs in Saltwood — part of the CT postcode area — go to vans that likewise cover the locations round it, Hythe, Orchard Valley and Sandling among them. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians work, and the vehicle doesn't need to move to us.
At the pump around Saltwood, right now?
Then, you couldn't be in a better place. Ring, and leave it switched off.