Should You Worry? Petrol in a Diesel Car in Sawston
Probably less than you already are — as long as no one has started the vehicle. "Have I wrecked it?" is the first question everyone around Sawston asks, and the truthful answer is normally no, since petrol left in a diesel tank harms nothing until it's dragged through the fuel system — by ignition priming, by the starter, or by being driven. To leave it that way, phone Petrol in Diesel and leave the engine switched off. Keep reading for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and the way to make sure you never repeat it.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two jobs. It lubricates to begin with, and only then does it burn. What keeps the surfaces inside the high-pressure pump and the injectors from grinding against one another is your diesel flowing through them — they are designed to extremely fine gaps.
Petrol handles the first task badly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication the system depends on, and any pump running on that blend is wearing itself.
Together, those make the shape of the trouble clear. Contact doesn't do the harm — circulation does. Petrol in the tank is a fuel fault. Whatever a worn pump sheds goes on, carried by your fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical issue starts.
Sawston, petrol in a diesel: four cases, from mild to major
Filled up, and not started: no case is better. Only your tank has petrol in it, and so the task is draining that tank and purging the fuel system where your car stands. This situation can only truly occur on a forecourt: anywhere else, the car got there by being driven.
The ignition turned on, or a brief start. With your system primed, your lines and filter already contain petrol that has come from the tank. Usually nothing more than emptying, purging and sorting your filter, so still straightforward.
Those few miles on the road were your pump labouring on fuel diluted by petrol the whole way. Tank, lines, filter, then fresh fuel put through the entire system: that is this work, and the way the vehicle was driven matters as much as the miles. A school run to The Bellbird Primary School is one thing. Driving as far as Cambridge, under 10 miles away, makes a very different job — as does any distance on the M11, under 3 miles from Sawston, with your engine labouring hard all the way.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. The fuel is not acting like diesel any more, and your engine is saying so. Pull up on the spot — on the verge on Mill Lane, at the kerb, down a side road — and do not move it. The drain and flush still go first, and they take care of it: if a vehicle is pulled over soon, lasting damage is very unusual.
What Sawston drivers get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice supposes.
Myth: a newer diesel copes with a bit of petrol. If anything, the reverse. At higher pressure, through smaller parts: that is how a current diesel moves its fuel, so the lubrication counts more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that fools drivers. Diesel in a petrol motor generally leaves a motor that will not run: the motorist stops, and so does the damage. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Running does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate problem. What petrol has weakened stays weakened, and that petrol remains inside the tank anyway.
The next start draws petrol back round your pump from the lines and the fuel filter, where some of that ends up after the motor has run. That is why draining your tank yourself does not leave you sorted — a myth. Besides, petrol emptied into a can by the road is truly risky.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way.
Habit and the car getting out of step is when it takes place. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. A forecourt you know, only with its pumps arranged differently. A train to catch, and a hurried fill on the way to Whittlesford Parkway. A new-to-you diesel Volkswagen Tiguan, its first fuelling, and a motorist accustomed to petrol: exactly when it happens. Throw in rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Preventing petrol in a diesel next time you fill up in Sawston
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on every forecourt. The label is what matters.
- Many cars state the fuel inside your filler flap or on the cap, and so check there on the first fill in a car you do not know.
- One of each in the house? Label the key to the diesel — a coloured fob, a sticker — since intending to remember isn't enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It sounds daft and it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Some diesels come with a filler designed to block a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Noticing it mid-fill? Stop at once. A weaker mixture results from less petrol in the tank, yet your next step remains the same: do not start it.
Put petrol in a diesel in Sawston already?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. Ask the attendants to help you roll it away from the petrol pump if you are still on the forecourt, whether that is BP or anywhere else. Call 0333 366 0103 next, with three answers — your fuel, the approximate amount, and if it has run.
Corrosion and deposits form the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Sawston page.
Why one petrol in a diesel job around Sawston costs more than another
There's no honest single price for this, since the four scenarios above are four separate jobs. What shifts your cost is mostly which of them you're in. The share matters next, meaning how much of that tank is petrol, followed by the position of the car and whether reaching it is safe for a van.
Three questions come first, before any quote, instead of after — what was put in, how much, has it run — and that is the reason. A range turns into a straight figure when those replies are in.
About Sawston, for a moment
Sawston is a village in Cambridgeshire, situated on the River Granta, with a mix of semi-detached housing and other residential properties. Sawston lies close to the city of Cambridge, about 6 miles to the south, and is surrounded by other villages such as Pampisford and Whittlesford. Sawston has a population of around 2428 people and is located at an elevation of approximately 25 metres above sea level. Sawston is also within commuting distance of London, being about 44 miles from the capital.
Fuel drain cover in Sawston and across Cambridgeshire
Our teams answering petrol in diesel call-outs in Sawston, in the CB postcode area, equally work the spots around it, Pampisford, Whittlesford and Babraham included. A forecourt, a supermarket car park, a lay-by or your own drive are all places we drain, and your vehicle doesn't need to move to us.
At the pump in Sawston, right now?
Then, you could not be in a better position. Keep the car turned off, and ring.