How Worried Should You Be? Petrol in a Diesel Car in Highgate
Likely less than you are now — as long as nobody has started the vehicle. Petrol resting in a diesel tank does nothing to the motor until something draws it through the system — your ignition priming your pump, your starter, or driving on its own. So the honest answer to the first question everyone in Highgate asks, "have I ruined it?", is generally no. Keep it that way: leave the motor off then phone Petrol in Diesel. Below, this page sets out what petrol actually does inside a diesel, how far it might have gone, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel has two tasks. Before it ignites, it protects — then it ignites. What stops the surfaces inside the high-pressure fuel pump and the fuel injectors from grinding against one another is the diesel passing through them — they are designed to very fine gaps.
Petrol does the first task badly and the second not at all. It is runnier than diesel and strips away the lubrication your fuel system hinges on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the clattering comes from.
Put these together and the shape of the issue is clear. The harm is done by movement, not by contact. Any tank with petrol in it is a fuel fault. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
How serious is petrol in a diesel? Four situations we see in Highgate
Filled up, not once started. The best case there can be. Just that tank has petrol in it, and so the job is draining your tank and rinsing the fuel system where your car stands. This scenario can only really occur at a forecourt: anywhere else, the car got there by being driven.
A brief spell of running, or just the ignition on. Petrol has left that tank and reached the fuel filter and the lines, since the fuel system has been bled. Still generally simple: drain, flush, and the fuel filter dealt with.
Those few miles driven were your pump labouring on fuel thinned by petrol throughout. Tank, lines, filter, then fresh fuel run through the entire circuit: that is the work, and the way your car was driven matters as much as the miles. On the school run to Hawkhurst Church of England Primary School, the mileage is short. Getting as far as Canterbury, under 50 miles away, makes a very different task — as does any mileage on the M20, under 15 miles from Highgate, with your engine labouring hard all the way.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. What you are hearing is your motor signalling fuel that no longer behaves like diesel. Leave it wherever it stops: a lay-by, a quiet street, the verge on Norris Close. What goes first is still the drain and flush, and that sorts it out, with lasting damage very uncommon when a vehicle is stopped soon.
Myths Highgate people hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A fuller tank of the same mixture is all you get, since topping up takes out nothing. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice presumes.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. A current diesel runs its fuel through finer parts at higher pressure, which makes the protection count more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more drivers than any other. Diesel in a petrol motor generally leaves a motor that won't run: the driver stops, and so does the damage. Feed petrol to a diesel and it normally fires up, ticks over and drives away as if nothing has happened — all the while its pump wears. Running does not mean fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another problem. What petrol has weakened stays thinned, and that petrol stays inside that tank regardless.
Myth: "Drain that tank yourself and you are sorted." After the motor has been run, some of the petrol is no longer in that tank: it is in your filter and your lines, and it goes straight back through the pump on your next start. It's also really hazardous to drain petrol into a can at the roadside.
How it happens: petrol in a diesel
Carelessness is seldom the cause, and no one means to do it. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol motor. That is how the forecourt makes it straightforward.
It happens when routine and the car stop matching. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the driveway of the same household. A familiar forecourt with the pumps in a different order. Racing for a train outside Etchingham and fuelling up en route. Years of petrol vehicles behind you, a diesel Renault Clio in front of you at the forecourt for its first tank — that is when. Your hand does what it has always done when you add rain, a phone call or a back seat full of children.
Next time you fill up around Highgate: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Trust the label on the pump, not the colour.
- The first fill in an unfamiliar motor is the time to check your filler flap — on it, or on the cap, plenty of vehicles state which fuel to use.
- Mark 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 meaning to remember.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Silly, yes, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, and so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, then keep checking the pump.
- Stop the moment you realise. Less petrol inside the tank means a weaker mixture. It does not change what to do next, which is still not to crank it.
Put petrol in a diesel around Highgate already?
Then the order of things is short. Don't switch the ignition on, and do not fire it up. Ask the attendants to help you push it clear of the petrol pump if you're still on the forecourt, whether that's BP or somewhere else. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it's a separate fault, with its own page for Highgate, because AdBlue brings corrosion and deposits instead of lost protection.
Highgate petrol in a diesel tasks: why one costs more than another
A fair single quote doesn't exist here: four situations, four separate tasks. The situation itself does most of the work of moving your cost. Next it's the proportion — how much petrol got in against how much that tank holds — and after that where the car is and whether our van can get to it safely.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and this is the reason. Given the replies, you get a straight figure rather than a range.
About Highgate and where it is
Highgate is a suburban area in Kent, situated lakeside with an elevation of around 75 metres. Highgate lies near several smaller communities, including Hawkhurst, Beals Green, and Pipsden, and is approximately 29 miles from Canterbury. Highgate has a population of around 2737 people and is characterised by semi-detached housing. Highgate is also within commuting distance of London, being about 42 miles from the city.
Highgate and Kent: where our fuel drain cover runs
Hawkhurst, Beals Green and Pipsden are among the spots near Highgate that the same teams work, answering petrol in diesel calls across Highgate's TN postcode area. No need to bring your car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places where we work.
At the pump around Highgate, still?
Then you're in the best position there is. Leave it turned off, then ring.