Petrol in a Diesel Car in Hare Street: How Worried Should You Be?
Not started? Then less worried than you likely feel. Petrol resting in a diesel tank does nothing to the engine till something draws it through the fuel system — your ignition priming your pump, the starter, or driving on its own. So the honest answer to the first question anyone around Hare Street asks, "have I wrecked it?", is generally no. Keep it that way: leave the engine off then ring Petrol in Diesel. The remainder of this page sets out what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
Inside the engine: what petrol in a diesel really does
On its way through a motor, diesel does two jobs. Before it combusts, it protects — then it burns. What keeps the surfaces inside your high-pressure pump and your injectors from grinding against one another is the diesel passing through them — they are designed to extremely fine clearances.
The second task petrol doesn't do at all, and the first it does badly. It is thinner than diesel and removes the lubrication the system hinges on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the issue is clear when you put those together. The damage is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel fault. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors further on.
Four situations we see in Hare Street: how serious is petrol in a diesel?
Fuelled but not once started — as good as it gets. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol held in your tank alone, it's drained and flushed right where it stands, and nothing more is needed.
The ignition switched on, or a short start. Your system has been primed, so petrol has left the tank and reached the filter and the fuel lines. Usually nothing more than draining, flushing and seeing to the fuel filter, and so still simple.
A couple of miles driven, and your pump has spent every one of them working on thinned fuel. The work is that tank, the lines, the fuel filter and clean fuel through the entire circuit, and how hard the car was driven counts as much as how far. On the school run to Hare Street Community Primary School and Nursery, the distance is short. Driving as far as Chelmsford, under 25 miles away, makes a very different task — as does any mileage on the M11, under 3 miles from Hare Street, with your engine working hard all the way.
Clattering, an uneven idle, smoke, a throttle gone soft: driven until it complained. That's the engine telling you its fuel no longer is acting like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Helions Road. What goes first is still the drain and flush, and that deals with it, with long-term damage very unusual if a car is pulled over soon.
Petrol in a diesel myths Hare Street drivers hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage isn't how a diesel fuel system copes with petrol, however much that advice assumes.
Not so: a newer diesel copes with a bit of petrol. If anything, the reverse. Lubrication matters more on modern diesels, not less, since their fuel passes through finer parts at higher pressure.
"It starts, it drives, and so no harm done" — the myth that trips up more motorists than any other. Diesel in a petrol motor generally means a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally starts, ticks over and pulls away as if nothing happened — all while its pump is wearing. Running isn't the same as fine.
An outdated workaround for a separate problem is behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol weakened is put back by it — and later, that tank still contains the petrol.
Myth: "Drain your tank yourself and you're sorted." After the motor has been run, some of the petrol is no longer in that tank: it is in the filter and your lines, and it goes right back through the pump at the next start. Draining petrol into a can by the kerbside is also truly hazardous.
How does petrol in a diesel occur?
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle mostly will not fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in one direction.
The moment habit stops matching your car is the moment it takes place. Any motor that's new to you — hired, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. A hurried fill en route to Harlow Town with a train to catch. Years of petrol vehicles behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that's when. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
Preventing petrol in a diesel next time you fill up around Hare Street
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is just a clue.
- In a motor you don't know, look inside the flap over your filler or at the cap before the first fill: many vehicles state the fuel there.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, in a house with one of each.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds daft. It works.
- Whilst you are 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 designed to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol inside your tank means a thinner mixture. It does not change what to do next, which is still not to fire it up.
Hare Street: already put petrol in a diesel?
Then the order of things is short. Leave it unstarted, with your ignition off too. If you are still on the forecourt — Esso or anywhere else — ask the attendants to help you push it away from the petrol pump. Call 0333 366 0103 next, with three facts — the fuel, the approximate volume, and whether it has run.
If it was AdBlue instead of petrol, say so. That's a different issue — corrosion and deposits instead of lost lubrication — and it has its own page for Hare Street.
What makes one Hare Street petrol in a diesel task cost more than the next
Four separate jobs lie behind the four scenarios above — which is why there's no honest single quote. What moves your cost is mostly which of them you are in. Two things follow that: the petrol that went in as a share of what that tank takes, then the place your car is in and whether our van can reach it safely.
That is why our engineers ask three questions before quoting rather than after: what went in, how much, and if it has run. Those answers are what change a range into one firm number.
About Hare Street itself
Hare Street is a suburban area in Essex, situated on the riverside with an elevation of around 65 metres. Hare Street lies approximately 20 miles from London and is close to the nearby cities of Chelmsford and Harlow. Hare Street has a mix of housing types, but is predominantly characterised by terraced homes. Hare Street is near other local areas such as The High and Little Parndon.
Fuel drain cover around Hare Street and across Essex
The vans answering petrol in diesel call-outs in Hare Street, in the CM postcode area, also work the spots around it, The High, Little Parndon and Harlow among them. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our engineers drain, and the car doesn't need to move to us.
At the petrol pump in Hare Street, right now?
The best position there is, then — that is where you are. Keep it turned off, and ring.