How Worried Should You Be? Petrol in a Diesel Car in Heston
Far less than you likely are, if it hasn't been started. Everyone in Heston starts with "have I wrecked it?", and the honest answer is usually no: petrol left inside your tank of any diesel stays harmless till priming, cranking or driving pulls it into your fuel system. To keep the vehicle that way, ring Petrol in Diesel and leave your engine alone. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you again.
Inside your engine: what petrol in a diesel really does
Passing through a motor, diesel does two jobs at once. Before it combusts, it protects — and then it ignites. What keeps the surfaces inside the high-pressure pump and the injectors from grinding against one another is your diesel passing through them — they're built to extremely fine tolerances.
The second job petrol doesn't do at all, and the first it does poorly. The clattering comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection your system hinges on, and any pump working on such a blend is wearing itself.
Taken together, they show the shape the problem takes. The damage is done by circulation, not by contact. Any tank with petrol in it is a fuel problem. Once the pump has been working on that petrol, a mechanical problem has begun: anything shed by a pump that is wearing travels downstream to your injectors with your fuel.
How bad is petrol in a diesel? Four situations we see in Heston
The best case there is: filled up, not once started. At a forecourt, and truly only there, that petrol is still confined to the tank — because anywhere else your car was driven to reach it. The task is draining and cleaning on the spot.
Ignition on, or started for a second. With your system primed, the lines and filter already hold petrol that came from that tank. Usually nothing more than emptying, flushing and sorting the filter, and so still easy.
Driven a couple of miles. Now your pump has spent these miles labouring on thinned fuel. How hard the vehicle was driven matters as much as how far, and this work covers that tank, your lines, the fuel filter and clean fuel through the whole circuit. Driving the children to Springwell School is one kind of trip. Any distance on the M4, under a mile from Heston, means your engine has worked hard throughout, and a run to Westminster, under 15 miles away, is a very different task too.
Driven till it protested. Clattering, a ragged idle, smoke, a throttle that has gone soft. The fuel isn't behaving like diesel any more, and the engine is telling you. Leave it wherever it stops: a lay-by, a side street, the verge on The Croft. What goes first is still the drain and flush, and that takes care of it, with long-term damage very unusual if a vehicle is pulled over soon.
What Heston 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'll be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. Lubrication counts more on modern diesels, not less, since their fuel passes through more precise parts at higher pressure.
This is the one that catches people. Myth: "If it starts and drives, there is no damage done." Any petrol motor fed diesel generally will not run, and so the driver stops and the damage stops with them. Feed petrol to a diesel and it usually fires up, ticks over and pulls away like nothing happened — all the while its pump is wearing. Being able to run isn't the same as being fine.
An outdated fix for a different issue lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." What petrol has weakened remains thinned, and that petrol remains inside the tank regardless.
If the motor has run, part of the petrol sits in the fuel filter and the lines, not your tank — and the next start pulls it right back through the pump. So the myth "drain that tank yourself and you are sorted" does not hold. And, a can of petrol filled by the kerbside is truly hazardous.
Petrol in a diesel: how does it occur?
Nobody does it on purpose, and it's rarely carelessness. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way.
The moment habit stops matching the car is the moment it takes place. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. Racing for a train outside Southall and fuelling up en route. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
Heston drivers: how to avoid petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — but not on every forecourt. Go by the label on the petrol pump, not the colour.
- The first fill in a new vehicle is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a house with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds silly and it does the trick.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels have a filler designed to refuse a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Spotting it mid-fill? Stop at once. A weaker mix results from less petrol in your tank, yet your next stage stays the same: do not fire it up.
Heston: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition switched off as well. If you are still on the forecourt — BP or anywhere else — ask the staff to help you push the car clear of the petrol pump. Phone 0333 366 0103 next, with three facts — the fuel, the approximate amount, and if it has run.
Corrosion and deposits form the problem with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Heston page.
What makes one Heston petrol in a diesel task cost more than the next
A fair single price does not exist here: four scenarios, four separate tasks. Which of them you're in is mostly what moves your cost. Where the vehicle is matters too, and whether our van can safely reach it, after the share of petrol to what the tank holds.
Three queries come first, before any quote, instead of after — what got in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number.
About Heston and its setting
Heston is a suburban area in west London, situated approximately 11 miles from Westminster and close to the neighbouring areas of North Hyde, Norwood Green, and Hounslow West. Heston lies at an elevation of around 32 metres, in a generally low-lying part of the London Basin. Heston has a population of around 11,060 people, with a predominance of semi-detached housing stock. Heston is characterized by its residential streets and local amenities.
Heston and Greater London: where our fuel drain cover runs
North Hyde, Norwood Green and Hounslow West are among the locations around Heston that the same vans work, answering petrol in diesel jobs across Heston's TW postcode area. No need to move your car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
In Heston and still at the petrol pump?
The best spot there is, then — that's where you are. Switched off it stays; then phone.