How Worried Should You Be? Petrol in a Diesel Car in Astrop
Less than you probably are, provided it hasn't been started. Petrol sitting in a diesel tank does nothing to the motor until something draws it through the system — your ignition priming your pump, the starter, or driving itself. So the fair answer to the first query everyone around Astrop asks, "have I ruined it?", is generally no. Petrol in Diesel is who to phone, with your motor kept off, and so it remains that way. Further down, this page sets out what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel really does
Diesel has two tasks on its way through a motor. Lubricating comes before burning; it does both. What keeps the surfaces inside the high-pressure fuel pump and your injectors from wearing down against each other is the diesel passing through them — they are built to extremely fine clearances.
The second job petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump running on that mixture to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the knocking.
The shape of the problem is clear once you put those together. Contact doesn't do the harm — circulation does. Where the petrol is only in the tank, it's a problem of fuel, nothing more. 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 your injectors further on.
How serious is petrol in a diesel? Four scenarios our engineers see in Astrop
Fuelled up, not once started. The best case there is. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With that petrol held inside that tank alone, it is drained and rinsed right where it stands, and nothing more is needed.
The ignition switched on, or a brief start. Petrol has left your tank and got to the fuel filter and the fuel lines, because the system has been primed. Still usually simple: drain, flush, and your filter dealt with.
Those few miles driven meant your pump working on fuel thinned by petrol throughout. How hard the car was driven counts as much as how far, and the work covers your tank, your lines, your filter and fresh fuel through the whole system. Driving the children to Kings Sutton Primary Academy is one sort of trip. Getting as far as Oxford, under 25 miles away, makes a very different job — as does any mileage on the M40, under a mile from Astrop, with your engine working hard all the way.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven until it complained. That's the motor telling you its fuel no longer is acting like diesel. Stop wherever you are — the verge on Upper Astrop Road, a lay-by, a side street — then leave the vehicle there. A vehicle pulled over soon very seldom has long-term damage, because the fuel drain and the flush-through, which still come first, sort it out.
Petrol in a diesel stories Astrop people hear
Myth: topping up to full with diesel makes it fine. It doesn't. Topping up removes nothing; it gives you a fuller tank of the same mix. That advice presumes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: a current diesel copes with a bit of petrol. If anything, the reverse. Smaller components and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
"It starts, it drives, so there is no harm" — the myth that trips up more drivers than any other. Feed diesel to a petrol engine and it generally won't run, and so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it usually fires up, idles and drives away like nothing has happened — all the while its pump is wearing. Being able to run isn't proof of being fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated fix for a separate issue. That petrol is still inside the tank after that, and whatever it has weakened isn't put back.
If the motor has been run, part of the petrol sits in the filter and your lines, not the tank — and your next start sends it straight back through the pump. So the myth "drain that tank yourself and you are sorted" does not hold. Besides, petrol emptied into a can by the road is truly risky.
How it happens: petrol in a diesel
Nobody does it on purpose, and it's rarely carelessness. A diesel nozzle mostly won't 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 straightforward, and just in one direction.
It occurs when routine and the vehicle 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 forecourt you know, only with its pumps laid out differently. Fuelling up in a hurry on the way to Kings Sutton, with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Passat in front of you at 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.
How to avoid petrol in a diesel at your next fill-up around Astrop
- The label is what matters, and so read the petrol pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- The first fill in a strange motor is the time to check the filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key if a household has one of each. So label it.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, yet it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to reject a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a safety net, and keep checking the pump.
- Spotting it mid-fill? Stop there and then. A weaker blend results from less petrol inside your tank, yet your next stage remains the same: do not start the vehicle.
Put petrol in a diesel in Astrop already?
Then the order of things is short. Don't switch your ignition on, and do not start it. Ask the attendants to help you roll it clear of the pump if you are still at the forecourt, whether that's Esso or somewhere else. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and if it's run.
Corrosion and deposits are the issue with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and read its own Astrop page.
Astrop petrol in a diesel tasks: why one costs more than another
There's no fair single quote for this, because the four scenarios above are four different tasks. Which of them you are in is chiefly what moves your cost. The ratio matters next, meaning how much of your tank is petrol, and then the position of the vehicle and whether getting to it is safe for a van.
Before any quote, not after, come three queries: your fuel that went in, the amount, and whether it has run. That's why. A range turns into a straight figure once the replies are in.
About Astrop, for a moment
Astrop is a suburban area in Northamptonshire, situated inland at an elevation of around 110 metres, with semi-detached housing being the predominant type. Astrop lies approximately 18.7 miles from Oxford and 60.3 miles from London, placing it within commuting distance of both cities. Astrop is surrounded by nearby places such as Kings Sutton, Upper Astrop, and Walton Grounds, and has a population of around 1815 residents. Astrop forms a small but distinct community within the wider region.
Astrop and Northamptonshire: where our fuel drain cover reaches
Petrol in diesel call-outs around Astrop — part of the OX postcode area — go to vans that also cover the spots round it, Kings Sutton, Upper Astrop and Walton Grounds among them. The car doesn't need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Astrop?
Then, you could not be in a better position. Keep it turned off, and ring.