Petrol in a Diesel Car in Lode: How Worried Should You Be?
If it hasn't been started, you can worry far less than you likely are. Everyone in Lode begins with "have I wrecked it?", and the fair answer is generally no: petrol resting in that tank of a diesel remains harmless until priming, cranking or driving pulls it into the system. Petrol in Diesel is who to ring, with the engine kept off, so it stays that way. Keep reading for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and ways to make sure you don't do it again.
What petrol in a diesel does to the motor
Passing through a motor, diesel is doing two jobs at once. Oiling comes before burning; it does both. Very fine gaps go into the fuel injectors and the high-pressure pump, and only your diesel running through keeps those surfaces from grinding together.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on the blend wearing itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the knocking.
Taken together, they show what shape the issue has. It is movement that causes the damage, not contact. Any tank with petrol in it is a fuel problem. Whatever a worn pump sheds goes on, borne by your fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical problem starts.
Four scenarios we see in Lode: how bad is petrol in a diesel?
Filled up, never started. The best case there can be. Only the tank has petrol in it, so the task is emptying your tank and rinsing the fuel system where the car sits. This scenario can only truly take place at a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or just the ignition on. Petrol has left the tank and got to your filter and the fuel lines, since the system has been primed. Drain, flush, see to your filter: still usually easy.
A few miles driven, and your pump has spent every one of them working on weakened fuel. Tank, lines, filter, then clean fuel run through the entire circuit: that's this work, and the way the vehicle was driven counts as much as the mileage. Short trips, such as the school run to Swaffham Bulbeck Church of England Primary School, are one matter. Very different again: a run to Cambridge, under 10 miles away, or any mileage on the M11, under 10 miles from Lode, where the engine never stopped labouring hard.
Driven till it complained. Knocking, a ragged idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and the engine is telling you. Whether it is the verge on Abbey Lane, a lay-by or a side road, stop where you are then leave it. Permanent damage is very unusual when a car is stopped quickly, and the drain and flush-through that still come first take care of it.
What Lode people 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 comes out when you top up — that tank simply holds more of the same blend. The assumption behind the guidance — that diesel fuel systems accept petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. Smaller components and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
This is the one that catches drivers. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol engine and it generally will not run, and so the motorist stops — and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, while the pump grinds. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a different fault. None of what petrol weakened gets put back by it — and afterwards, your tank still holds the petrol.
Myth: "Drain that tank yourself and you are sorted." Once the motor has run, some of that petrol is no longer in that tank: it's in the fuel filter and your lines, and it goes right back through the pump at the next start. It is also really hazardous to drain petrol into a can by the roadside.
Why petrol in a diesel occurs so easily
No one does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol motor at all. The forecourt makes it easy, and the mistake runs one way.
When routine and your car stop matching, it takes place. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. Racing for a train at Waterbeach and fuelling up en route. Years of petrol cars behind you, a diesel Renault Clio in front of you on the forecourt for its first tank — that is when. Add a back seat full of kids, a phone call or rain, and habit wins.
Next time you fill up around Lode: preventing petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — yet 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 your first fill: plenty of motors print the fuel type there.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a household with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds silly and it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices exist for vehicles without one. They are a backstop, not a reason to stop checking the pump.
- Stop the moment you realise. Less petrol inside that tank means a thinner blend. It doesn't change what to do next, which is still not to fire it up.
Put petrol in a diesel in Lode already?
Then the order of things is brief. Starting it is out, and so is switching on your ignition. If you're still on the forecourt — BP or anywhere else — ask the staff to help you push the vehicle clear of the pump. What went in, roughly how much, and whether it's run: tell us that when you phone 0333 366 0103.
If it was AdBlue instead of petrol, say so. That's a different fault — corrosion and deposits and not lost lubrication — and it has its own page for Lode.
Lode petrol in a diesel jobs: why one costs more than another
An honest single quote does not exist here: four situations, four separate jobs. What moves the cost is mostly which of them you're in. Where the vehicle is matters too, and whether a van can safely reach it, after the ratio of petrol to what the tank holds.
Three queries come first, before any quote, rather than after — what went in, how much, has it run — and this is the reason. A range becomes a straight figure when the replies are in.
About Lode itself
Lode is a small village in Cambridgeshire, situated on the riverside at a low elevation of around 8 metres. Lode lies near the city of Cambridge, approximately 5.9 miles to the east, and is surrounded by nearby places such as Long Meadow, Bottisham, and Swaffham Bulbeck. Lode has a population of around 672 people and predominantly consists of detached housing.
Lode and Cambridgeshire: where our fuel drain cover reaches
Lode rests in the CB postcode area, and our vans that answer petrol in diesel jobs there work the locations near it as well — Long Meadow, Bottisham and Swaffham Bulbeck among them. The vehicle doesn't need to come to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the petrol pump in Lode, right now?
Then you're in the best spot there can be. Keep it switched off, then ring.