Fernhurst: Petrol in a Diesel Car? How Worried to Be
Provided it has not been started, worry less than you probably are. Till the ignition primes your pump, the starter turns, or your vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which makes the truthful reply to the first Fernhurst question — "have I ruined it?" — usually no. Leave the engine off then call Petrol in Diesel — that is how you keep it that way. Further down, you will find what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what happens
Passing through an engine, diesel does two jobs at once. It protects first, and after that does it burn. Extremely fine clearances go into the injectors and your high-pressure pump, and just your diesel flowing through keeps those surfaces from grinding together.
Petrol does the first task badly and the second not at all. The clattering comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system depends on, and any pump working on such a mix is wearing itself.
Taken together, they make clear the shape the problem takes. The harm is done by movement, not by contact. Where that petrol is only in the tank, it is a problem of fuel, nothing more. Once your pump has been running on that petrol, a mechanical issue has started: whatever is shed by a pump that's wearing is carried onward to your injectors with the fuel.
Four situations we see in Fernhurst: how serious is petrol in a diesel?
Fuelled up, never started. The best case there is. On a forecourt, and genuinely only there, the petrol is still confined to that tank — since anywhere else the vehicle was driven to reach it. The task is emptying and rinsing on the spot.
Ignition on, or started for a second. Petrol has come out of your tank and got to the filter and the lines, since the system has been primed. Drain, flush, deal with your filter: still usually easy.
A couple of miles driven, and the pump has spent each of them running on diluted fuel. Distance is only half of that; how hard it was driven counts equally. Either way the work includes the tank, the lines, the fuel filter and clean fuel through the whole system. A school run to Fernhurst Primary School is one matter. Any mileage on the Waterlooville Bypass, under 15 miles from Fernhurst, means the motor has worked hard throughout, and a run to Chichester, under 15 miles away, is a very different task as well.
Driven on till it complained — knocking, smoke, a lumpy idle, a dead throttle. The engine is telling you your fuel is no longer acting like diesel. Pull up wherever you are — the verge on Vann Road, a lay-by, a side street — and leave it where it is. Permanent damage is very unusual when a car is stopped quickly, and the drain and flush that still come first deal with it.
Fernhurst people and the petrol in a diesel myths they hear
False: topping up to full with diesel makes it fine. It does not. Topping up removes nothing; it gives you a fuller tank of the same mix. That advice supposes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. A newer diesel runs its fuel through more precise parts at higher pressure, which makes the lubrication matter more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it generally won't run, and so the motorist stops — and the damage stops with them. Whilst the pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive it home." It is an outdated fix for a separate problem. What petrol has diluted remains diluted, and that petrol stays inside that tank anyway.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol lies in the filter and lines, ready to go right back through your pump at your next start. On top of that, petrol drained into a can by the road is genuinely risky.
How does petrol in a diesel happen?
No one does it on purpose, and it's rarely carelessness. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol car at all. The forecourt makes it easy, and the error runs one way.
Routine and the vehicle getting out of step is how it occurs. A vehicle that's new to you — hired, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. Fuelling up in a rush on the way to Haslemere, with a train to catch. A new-to-you diesel Volkswagen Tiguan, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. Add a back seat full of children, a phone call or rain, and the hand wins.
Preventing petrol in a diesel next time you fill up around Fernhurst
- A green handle for unleaded and black for diesel is normal in the UK — yet not on each forecourt. Trust the label on the petrol pump, not the colour.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of vehicles state the fuel there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, in a house with one of each.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Whilst you're 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 come with a filler designed to block a petrol nozzle, and add-on devices exist for the remainder. Treat it as a backstop, and keep reading the petrol pump.
- Less petrol means a weaker mix, and so stop as soon as you realise — though remembering that your next stage is unchanged. It is still not to start the car.
Already put petrol in a diesel in Fernhurst?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. Still on the forecourt, at Arnolds Garage or anywhere else? Ask the staff to help you push the car clear of the pump. What was put in, about how much, and if it's run: tell us that when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a different problem — corrosion and deposits instead of lost lubrication — and it has its own page for Fernhurst.
Why one petrol in a diesel task in Fernhurst costs more than another
The four situations above are four different tasks, so no single quote for this would be honest. The situation itself does most of the work of moving the cost. Two things follow that: the petrol that was put in as a share of what that tank holds, then the place the car is in and whether a van can get to it safely.
Three queries come first, before quoting, rather than after — what was put in, how much, has it run — and this is the reason. Those replies turn a range into a straight figure.
About Fernhurst
Fernhurst is a village in West Sussex, situated inland at an elevation of around 90 metres, with detached housing being the predominant type of accommodation. Fernhurst lies approximately 14.9 miles north of Chichester and 40.8 miles south-west of London, near to Hatch Farm Hill and Kingsley Green. Fernhurst has a population of around 1830 residents, and its location in the South East region makes it a popular choice for those seeking a rural lifestyle. Fernhurst is surrounded by scenic countryside, including the nearby Marley Heights.
Across West Sussex and around Fernhurst: fuel drain cover
Our vans answering petrol in diesel jobs around Fernhurst, in the GU postcode area, also work the spots around it, Hatch Farm Hill, Kingsley Green and Marley Heights included. Our technicians drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Fernhurst and still at the petrol pump?
No position is better: that's where you now are. Phone, and keep it turned off.