Should You Worry? Petrol in a Diesel Car in St Helena
Less than you probably are, provided it hasn't been started. Everyone around St Helena begins with "have I wrecked it?", and the fair answer is normally no: petrol left in that tank of any diesel remains harmless till priming, cranking or driving pulls it into the system. Petrol in Diesel is who to call, with your engine left off, so it remains that way. What petrol actually does to a diesel, how to gauge how far it's gone, and how to keep it from happening a second time: that's the rest of this page.
Inside the motor: what petrol in a diesel really does
Passing through an engine, diesel is doing two things at the same time. It ignites, and before it burns it lubricates. Made to extremely fine gaps, the injectors and your pump rely on your diesel moving through them to keep their surfaces from wearing against one another.
Badly at the first, not at all at the second: that is petrol. It's runnier than diesel and strips away the lubrication the fuel system hinges on, 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 is where the rattling comes from.
Seen together, they make clear the shape the issue takes. The harm is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
How bad is petrol in a diesel? Four situations our engineers see around St Helena
Fuelled up, not once started. The best case there is. At a forecourt, and genuinely only there, that petrol is still limited to your tank — since anywhere else the car was driven to get to it. The job is emptying and flushing on the spot.
A moment's running, or just your ignition on. Once primed, your system has pulled petrol from that tank as far as the fuel filter and the fuel lines. Drain, flush, deal with your filter: still usually simple.
A few miles driven, and your pump has spent every one of them running on thinned fuel. Tank, lines, filter, then clean fuel put through the entire circuit: that's the work, and the way the vehicle was driven counts as much as the mileage. The school run to Birchwood Primary School is one matter. Very different again: a trip to Lichfield, under 15 miles away, or some mileage on the M42, under 3 miles from St Helena, where your engine never stopped working hard.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. The engine is telling you your fuel is no longer acting like diesel. Whether it is the verge on Park Road, a lay-by or a side street, stop there then leave it. What goes first is still the fuel drain and flush, and that deals with it, with long-term damage very rare when a vehicle is pulled over soon.
Petrol in a diesel stories St Helena drivers hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — your tank simply holds more of the same mixture. The assumption behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer components: that is how a newer diesel moves its fuel, and so the protection counts for more, not less.
One myth that catches people out: if it starts and drives, it must be unharmed. Any petrol motor fed diesel usually won't run, and so the motorist stops and the harm stops with them. Feed petrol to a diesel and it generally fires up, idles and pulls away like nothing has happened — all while its pump wears. Running isn't the same as fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a distinct issue. The petrol is still in the tank after that, and whatever it has weakened is not put back.
The next start sends petrol back round the pump out of the fuel lines and the filter, where some of that ends up after the motor has been run. That is why draining your tank yourself doesn't leave you sorted — a myth. Draining petrol into a can by the kerbside is also really hazardous.
How does petrol in a diesel happen?
It's rarely carelessness, and no one does it on purpose. One way only, since of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol motor. That is how the forecourt makes it straightforward.
When habit and your car stop matching, it takes place. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. A rushed fill en route to Polesworth with a train to catch. Exactly the moment it takes place: after years of driving petrol, a driver fills a diesel Renault Clio for the first time. With rain, a call coming in, or children to deal with, the hand just does what it always has.
Preventing petrol in a diesel next time you fill up in St Helena
- The label is what counts, so read the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- The first fill in a new vehicle is the time to check your filler flap — on it, or on the cap, plenty of motors state which fuel they take.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, for a household with one of each.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car needs its first tank. It seems silly. It works.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck your phone away and keep your mind on the petrol pump.
- Some diesels come with a filler designed to block a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Stop the moment you realise. Less petrol inside your tank means a thinner mix. It doesn't change what to do next, which is still not to crank it.
St Helena: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. If you're still at the forecourt — Polesworth Garage or anywhere else — ask the staff to help you roll the vehicle clear of the petrol pump. What went in, about how much, and if it has run: tell us those when you call 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own St Helena page.
What makes one St Helena petrol in a diesel task cost more than the next
The four scenarios above are four different tasks, so no single price for this would be honest. The scenario itself does most of the work of moving the cost. Two things follow that: the petrol that went in as a proportion of what your tank holds, then the place your car is in and whether a technician can reach it safely.
That is why our technicians ask three queries before quoting rather than after: what got in, how much, and whether it's run. Those replies change a range into a straight figure.
About St Helena
St Helena is a locality in Warwickshire, situated on the riverside at an elevation of 78 metres, with semi-detached housing being the predominant type of accommodation. St Helena lies near the cities of Lichfield and Tamworth, and is close to the villages of Polesworth, Dordon, and Birchmoor. St Helena is around 10 miles from Lichfield and approximately 99 miles northwest of London. St Helena has a population of around 1543 residents.
St Helena and Warwickshire: where our fuel drain cover reaches
Polesworth, Dordon and Birchmoor are among the locations near St Helena that the same vans work, answering petrol in diesel calls across St Helena's B postcode area. The car does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump in St Helena?
Then you're in the best place there is. Turned off it remains; then call.