How Worried Should You Be? Petrol in a Diesel Car in Hayes
Less than you likely are, if it has not been started. "Have I ruined it?" is the first thing anyone around Hayes asks, and the honest answer is usually no, since petrol resting in a diesel tank hurts nothing till it's dragged through your fuel system — by ignition priming, by your starter, or by being driven. Petrol in Diesel is who to phone, with the engine left off, so it remains that way. What petrol actually does to a diesel, how to judge how far it's gone, and how to stop it from happening again: that's the remainder of this page.
Inside your engine: what petrol in a diesel really does
On its way through a motor, diesel has two jobs. It protects to begin with, and only then does it burn. What stops the surfaces inside your high-pressure pump and your injectors from wearing down against each other is the diesel passing through them — they are built to very fine gaps.
Of those two jobs, petrol handles the first poorly and the second never. The rattling 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 runnier than diesel, it strips out the protection your system rests on, and any pump running on such a blend is wearing itself.
The shape of the problem is clear when you put those together. Contact doesn't do the harm — movement does. Where the petrol is only in the tank, it's a problem of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Hayes, petrol in a diesel: four situations, from mild to major
The best case there can be: filled up, not once started. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol kept in the tank alone, it's cleared and purged on the spot, and nothing more is needed.
Your ignition switched on, or a short start. With the fuel system primed, your lines and filter already hold petrol that has come from that tank. That's generally still a simple task — a drain, a flush, and the fuel filter seen to.
Those few miles driven meant your pump labouring on fuel diluted by petrol throughout. Miles is only half of it; how hard it was driven matters equally. Either way the work includes the tank, the lines, the fuel filter and clean fuel through the whole circuit. On the school run to Hayes Primary School, the mileage is short. Getting as far as Westminster, under 15 miles away, makes a very different task — as does any mileage on the M25, under 10 miles from Hayes, with the motor labouring hard the whole time.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven till it complained. That is your engine telling you its fuel no longer is acting like diesel. Stop where you are — on the verge on Hayes Lane, at the kerb, down a side road — and do not move it again. Lasting damage is very unusual when a vehicle is pulled over soon, and the drain and flush that still come first deal with it.
Petrol in a diesel stories Hayes motorists hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a fuller tank of the same mixture. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
Myth: a newer diesel copes with a bit of petrol. Rather, the opposite. More precise parts and higher pressure are how a modern diesel runs its fuel, and that makes the protection count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there's no harm done." The driver of a petrol motor fed diesel normally stops, since it will not run, and the damage stops with them. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, whilst your pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an outdated workaround for a separate problem. It doesn't put back what petrol has thinned, and the petrol is still in the tank after that.
Once the engine has run, part of that petrol sits in the filter and your lines, not that tank — and your next start sends it straight back through your pump. So the myth "drain the tank yourself and you're sorted" doesn't hold. Also, a can of petrol filled at the kerbside is genuinely hazardous.
How does petrol in a diesel occur?
It's rarely carelessness, and nobody does it on purpose. A diesel nozzle mostly will not go into a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and just in one direction.
The moment routine stops matching the vehicle is the moment it happens. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. Filling up in a hurry on the way to Hayes (Kent), with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. The hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Next time you fill up around Hayes: avoiding petrol in a diesel
- The label is what matters, and so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- Inspect the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in a motor you do not know.
- Label the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- While you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Add-on devices exist for cars without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside the tank makes a thinner mixture. What to do next doesn't change, though — still don't start the car.
Put petrol in a diesel around Hayes already?
The order of things is brief, then. Starting it is out, and so is switching on your ignition. Still at the forecourt, at Shell or anywhere else? Ask the staff to help you push it away from the petrol pump. Phone 0333 366 0103 next, with three answers — the fuel, the approximate volume, and whether it's run.
Corrosion and deposits are the problem with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Hayes page.
One petrol in a diesel job around Hayes costs more than another. Why?
The four scenarios above are four different tasks, so no single quote for this would be fair. What shifts your cost is mostly which of them you are in. Two things come after that: the petrol that was put in as a proportion of what that tank takes, then the place the vehicle is in and whether a technician can get to it safely.
What got in, how much, and if it's run — three queries our engineers ask before costing, not after, for exactly that reason. Their answers are what change a range into one firm number.
About Hayes and its setting
Hayes is a suburban area in Greater London, situated near the River Ravensbourne and characterised by semi-detached housing. Hayes sits at an elevation of around 63 metres, with Bromley Common and Coney Hall nearby. Hayes is located approximately 10.8 miles from central London, with Westminster about 10.4 miles away. Hayes has a population of around 4858 residents.
Across Greater London and around Hayes: fuel drain cover
Bromley Common, Coney Hall and Keston Mark are among the places near Hayes that the same vans work, answering petrol in diesel call-outs across Hayes's BR postcode area. Our engineers drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump in Hayes?
No position is better: that's where you are. Keep it off. Ring.