Petrol in a Diesel Car in Middle Bourne: How Worried Should You Be?
Provided it has not been started, you can worry less than you probably are. Everyone around Middle Bourne starts with "have I ruined it?", and the honest answer is generally no: petrol left inside your tank of any diesel stays harmless until priming, cranking or driving pulls it into your fuel system. Leave your motor off then call Petrol in Diesel — that keeps it like that. The rest of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to the engine?
Passing through a motor, diesel is doing two jobs at once. It lubricates first, and after that does it burn. What stops the surfaces inside your high-pressure pump and the fuel injectors from grinding against each other is the diesel passing through them — they are designed to extremely fine clearances.
The second job petrol does not do at all, and the first it does badly. It is runnier than diesel and removes the protection the system rests on, and 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 reverse of what a diesel needs from its fuel. That's where the clattering comes from.
Taken together, they show what shape the trouble has. It is circulation that causes the damage, not contact. A tank with petrol in it is a fuel issue. After your pump has been running on that petrol, a mechanical fault has begun: whatever is shed by a pump that's grinding travels downstream to the fuel injectors with the fuel.
How serious is petrol in a diesel? Four situations our technicians see in Middle Bourne
Fuelled up, never started. The best case there can be. That petrol is in that tank and only that tank, and the task is a drain and a flush where your car sits. This is the one scenario that can only really occur on a forecourt, because anywhere else the vehicle has been driven to get there.
Ignition on, or started for a second. Petrol has come out of the tank and reached your filter and the lines, because the system has been primed. Still usually simple: drain, flush, and the fuel filter sorted.
A few miles driven, and the pump has spent each of them labouring on diluted fuel. Tank, lines, filter, then clean fuel put through the entire system: that's this work, and the way your car was driven counts as much as the miles. Short trips, like the school run to St Peter's CofE Primary School, are one matter. Driving as far as Winchester, under 25 miles away, makes a very different task — as does any mileage on the M3, under 10 miles from Middle Bourne, with the motor working hard all the way.
Driven on until it protested — knocking, smoke, a ragged idle, a soft throttle. The motor is telling you the fuel is no longer acting like diesel. Pull up on the spot — on the verge on Celery Lane, at the kerb, down a side road — and do not move it again. Lasting damage is very unusual if a vehicle is stopped quickly, and the fuel drain and flush-through that still go first deal with it.
Middle Bourne motorists and that petrol in a diesel myths they hear
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 fuller tank, still the same mix. The assumption behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Protection matters more on modern diesels, not less, because their fuel runs through finer components at higher pressure.
The myth that catches people off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the damage. Whilst the pump grinds, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated fix for a separate fault. It does not put back what petrol has weakened, and the petrol is still in your tank later on.
Once the motor has run, part of the petrol is in your filter and the lines, not your tank — and your next start sends it right back through the pump. So the myth "drain that tank yourself and you're sorted" does not stand up. It's also really risky to drain petrol into a can by the roadside.
Petrol in a diesel: how does it happen?
Carelessness is seldom the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the slip runs one way.
The moment routine stops matching your car is the moment it occurs. Courtesy car, hire car, or a vehicle that's new. One petrol and one diesel on the drive of the same household. Your ordinary forecourt, its pumps now in a different order. Fuelling up in a rush en route to Farnham, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it happens. Add rain, a phone call or a back seat full of kids, and your hand does what it has always done.
Middle Bourne motorists: how to avoid petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Trust the label on the pump, not the colour.
- In a motor you do not know, look inside the flap over your filler or at the cap before the first fill: plenty of motors state the fuel there.
- Label 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 your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds daft and it works.
- While you're 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 block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the petrol pump.
- As soon as you realise, stop: less petrol inside your tank makes a weaker mix. What to do next doesn't change, though — still do not fire it up.
Petrol already in a diesel in Middle Bourne? Start here
The order of things is short, then. Starting it is out, and so is switching on your ignition. Yet at the forecourt, at Texaco or anywhere else? Ask the attendants to help you roll the car away from the petrol pump. Next, 0333 366 0103. We'll ask what got in, about how much, and if it has been run.
If it was AdBlue and not petrol, say so. That is a different fault — corrosion and deposits and not lost protection — and it has its own page for Middle Bourne.
One petrol in a diesel job around Middle Bourne costs more than another. Why?
The four situations above are four different tasks, so no single price for this would be honest. Which of them you're in is chiefly what moves the cost. Where your car is counts too, and whether our van can safely get to it, after the ratio of petrol to what your tank takes.
Three queries come first, before any quote, rather than after — what was put in, how much, has it run — and that is the reason. With the replies, you get a straight figure instead of a range.
About Middle Bourne
Middle Bourne is a suburban area in Surrey, situated near the river and characterised by detached housing. Middle Bourne sits at an elevation of 88 metres, within a short drive of nearby places such as The Bourne and Boundstone. Middle Bourne is located near the South East region's network of rivers and countryside, with London approximately 36 miles to the east. Middle Bourne remains a residential community with a population of around 2392 people.
Middle Bourne and Surrey: where our fuel drain cover runs
The Bourne, Boundstone and Shortheath are among the locations around Middle Bourne that the same vans work, answering petrol in diesel jobs across Middle Bourne's GU postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our technicians work, and your vehicle does not need to come to us.
Middle Bourne: still at the pump?
The best position there is, then — that's where you are. Keep it turned off, then ring.