Chatteris: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, provided it has not been started. Everyone in Chatteris starts with "have I ruined it?", and the fair answer is usually no: petrol resting in the tank of any diesel stays harmless until priming, cranking or driving pulls it into the fuel system. Leave the engine off and ring Petrol in Diesel — that keeps it like that. The rest of this page sets out what petrol really 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.
What petrol in a diesel does to your engine
On its way through an engine, diesel does two jobs. Lubricating comes before burning; it does both. Extremely fine tolerances go into the fuel injectors and the high-pressure pump, and just the diesel running through stops their surfaces grinding together.
The second job petrol doesn't do at all, and the first it does badly. It is thinner than diesel and strips away the protection the fuel system depends on, so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the rattling comes from.
Seen together, they show the shape the trouble has. It's circulation that causes the harm, not contact. Where the petrol is only inside that tank, it's a problem of fuel, nothing more. Whatever a worn pump sheds travels on, borne by the fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical issue starts.
Chatteris, petrol in a diesel: four situations, from mild to significant
Filled up, never started. The best case there is. That petrol is in the tank and just that tank, and the task is a drain and a flush where the car sits. This is the one situation that can only truly take place on a forecourt, since anywhere else your car has been driven to get there.
Your ignition turned on, or a brief start. With your system primed, the fuel lines and filter already hold petrol that came from that tank. That's normally still a straightforward job — a drain, a flush, and the filter seen to.
Driven a couple of miles. Now your pump has spent those miles working on diluted fuel. Miles is only half of that; how hard it was driven counts equally. Either way this work runs to that tank, the lines, your filter and fresh fuel through the entire system. On the school run to Kingsfield Primary School, the miles is small. Any distance on the A1(M), under 15 miles from Chatteris, means the motor working hard throughout, and a run to Ely, under 10 miles away, is a very different job as well.
Driven till it protested. Clattering, a ragged idle, smoke, a throttle that has gone soft. What you are hearing is the engine signalling fuel that no longer acts like diesel. Whether it's the verge on Railway Lane, a lay-by or a side road, stop there and leave it. What comes first is still the drain and flush-through, and that deals with it, with long-term damage very uncommon when a car is stopped early.
Petrol in a diesel stories Chatteris motorists hear
False: topping up to full with diesel makes it fine. It does not. Topping up takes out nothing; it gives you a bigger tank of the same mixture. Percentage is not how a diesel fuel system copes with petrol, whatever that guidance presumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. A newer diesel runs its fuel through finer components at higher pressure, which makes the protection matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there is no harm done." Any petrol engine fed diesel usually won't run, and so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally starts, ticks over and drives away like nothing happened — all while its pump is wearing. Being able to run isn't proof of being fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old fix for a separate fault. What petrol has thinned stays diluted, and that petrol remains in the tank regardless.
Once the motor has been run, part of that petrol sits in the filter and the lines, not the tank — and your next start pulls it straight back through your pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. It is also really dangerous to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle generally will not go into a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and just in that direction.
When habit and the car stop matching, it takes place. Any car that is new to you — hired, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. A well-known forecourt with the pumps in a different order. A rushed fill on the way to Manea with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. Add a back seat full of kids, a phone call or rain, and the hand wins.
Preventing petrol in a diesel next time you fill up in Chatteris
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on each forecourt. The label is what counts.
- Plenty of motors state the fuel inside the filler flap or on the cap, and so check it on the first fill in a motor you do not know.
- Label the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. It seems silly and it works.
- While you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to reject a petrol nozzle, and aftermarket devices exist for the rest. Treat it as a safety net, then keep reading the petrol pump.
- The moment you realise, stop: less petrol in that tank means a thinner mixture. What to do next does not change, though — still do not crank it.
Already put petrol in a diesel around Chatteris?
The order of things is brief, then. Do not fire it up, and don't switch your ignition on. Still at the forecourt, at BP or anywhere else? Ask the attendants to help you push it clear of the petrol pump. Then ring 0333 366 0103 and tell us what went in, roughly how much, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a different issue — Chatteris has a page all for it.
Why one petrol in a diesel job around Chatteris costs more than another
There's no honest single quote for this, because the four situations above are four different jobs. Mostly, your cost shifts with which situation you're in. The ratio matters next, meaning how much of your tank is petrol, and then the location of the vehicle and whether reaching it is safe for a technician.
Ahead of any quote, not after, we ask three queries: the fuel that got in, its quantity, and if it's run. That's why. Given those answers, there is a straight figure instead of a range.
About Chatteris
Chatteris is a town in Cambridgeshire, situated in the Eastern region of England, with a population of around 9987 people. Chatteris lies approximately 13 metres above sea level, close to the cities of Ely and Cambridge, and is characterised by its predominantly detached housing stock. Chatteris is surrounded by nearby places such as Swingbrow, Wenny Severals, and Horseway, and is about 66 miles from London. Chatteris has a mix of old and new buildings, reflecting its growth over time.
Fuel drain cover around Chatteris and across Cambridgeshire
The vans answering petrol in diesel calls in Chatteris, in the PE postcode area, also work the locations around it, Swingbrow, Wenny Severals and Horseway included. The car does not need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the petrol pump in Chatteris, right now?
Nothing beats it: that is where you now are. Leave the vehicle switched off, and ring.