Petrol in a Diesel Car in Hornsey: How Worried Should You Be?
Probably less than you are now — provided nobody has started the car. "Have I ruined it?" is the first thing everyone around Hornsey asks, and the honest answer is generally no, because petrol resting in a diesel tank hurts nothing until it's dragged through your fuel system — by ignition priming, by your starter, or by being driven. To keep the car like that, ring Petrol in Diesel then leave your engine alone. Further down, you will find what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to the motor
Diesel does two tasks on its way through an engine. It ignites, and before it burns it protects. What keeps the surfaces inside the high-pressure fuel pump and your injectors from wearing against each other is the diesel passing through them — they are designed to very fine clearances.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump on that mixture wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the rattling.
Combined, those leave the shape of the trouble clear. The harm is done by movement, not by contact. A tank with petrol in it is a fuel problem. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to the injectors downstream.
Hornsey, petrol in a diesel: four cases, from mild to significant
Filled up, and never started: no case is better. On a forecourt, and really only there, the petrol is still confined to the tank — because everywhere else the vehicle was driven to reach it. The task is draining and cleaning on the spot.
Started for a moment, or only the ignition on. Petrol has come out of your tank and got to your filter and your lines, since the system has been bled. Usually nothing more than clearing, rinsing and seeing to the fuel filter, and so still simple.
Your pump now spent a few miles on diluted fuel — that's what driving the vehicle does. How hard your car was driven matters as much as how far, and the work takes in your tank, your lines, the filter and fresh fuel through the whole circuit. Short trips, like the school run to St Mary's CofE Primary School, are one matter. Any mileage on the M1, under 5 miles from Hornsey, means the motor working hard throughout, and a run to London, under 10 miles away, is a very different task too.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. That is the engine telling you its fuel has stopped behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Myddelton Road. A car pulled over soon very rarely has lasting damage, because the fuel drain and the flush-through, which still come first, deal with it.
What Hornsey people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed when you top up — the tank just holds more of the same mixture. The idea behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer parts: that is how a current diesel moves its fuel, so the protection counts more, not less.
This is the one that catches people. Myth: "If it starts and drives, there's no damage done." A petrol engine fed diesel normally will not run, so the motorist stops and the harm stops with them. While your pump wears, a diesel fed petrol normally starts, ticks over and drives away as though nothing has happened. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated workaround for a different fault. What petrol has diluted stays thinned, and that petrol stays inside that tank anyway.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol sits in the fuel filter and lines, waiting to go straight back through the pump at the next start. Draining petrol into a can at the kerbside is also truly dangerous.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the error runs one way.
Routine and your car getting out of step is when it occurs. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps arranged differently. A hurried fill en route to the nearest station with a train to catch. A new-to-you diesel Peugeot 308, its first fuelling, and a motorist used to petrol: precisely when it takes place. The hand does what it has always done once you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel at your next fill-up in Hornsey
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Read the pump's label; the colour is only a clue.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: many motors print the fuel there.
- Label the key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for motors without one. They are a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you realise. Less petrol in that tank makes a weaker mixture. It does not change what to do next, which is still not to fire it up.
Petrol already in a diesel around Hornsey? Start here
The order of things is short, then. Starting it is out, and so is switching on your ignition. If you're still on the forecourt — Texaco or anywhere else — ask the attendants to help you roll the car away from the pump. Next, 0333 366 0103. We'll ask what got in, about how much, and if it has been run.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and read its own Hornsey page.
Why one petrol in a diesel task around Hornsey costs more than another
A fair single price doesn't exist here: four scenarios, four separate tasks. What shifts your cost is chiefly which of them you are in. Two things follow that: the petrol that got in as a proportion of what the tank holds, then the spot the vehicle is in and whether our van can reach it safely.
Three queries come first, before quoting, rather than after — what was put in, how much, has it run — and that is the reason. Their replies are what change a range into one firm number.
About Hornsey itself
Hornsey is a locality in north London, situated near the River Moselle and close to the outskirts of the capital city. Hornsey sits at a relatively low elevation of around 30 metres, with its riverside setting influencing the local environment. Hornsey is characterised by a high proportion of flat dwellings, reflecting its urban location. Hornsey is bordered by other local areas, including Hornsey Vale, Turnpike Lane, and Crouch End.
Fuel drain cover across Greater London, Hornsey included
Hornsey Vale, Turnpike Lane and Crouch End are among the locations around Hornsey that the same teams work, answering petrol in diesel call-outs across Hornsey's N postcode area. Our technicians drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Hornsey: still at the pump?
The best position there is, then — that is where you are. Keep it off. Call.