Shelone: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you probably feel. "Have I wrecked it?" is the first question everyone in Shelone asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing till it's dragged through your fuel system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to ring, with the motor kept off, and so it stays that way. The rest of this page sets out what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey round a motor. It lubricates first, and only then does it burn. Built to extremely fine clearances, the injectors and the pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Petrol handles the first job poorly and the second not at all. A pump working on a petrol blend is wearing itself out, because petrol is runnier than diesel and strips out the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that's where any rattling starts.
Together, those leave the shape of the trouble plain. Contact does not do the harm — movement does. Where the petrol is only in the tank, it is a problem of fuel, nothing more. Once the pump has been running on that petrol, a mechanical problem has started: whatever is shed by a pump that is wearing travels downstream to the injectors with the fuel.
How bad is petrol in a diesel? Four scenarios we see in Shelone
The best case there can be: filled up, never started. On a forecourt, and truly only there, the petrol is still confined to that tank — because anywhere else your car was driven to reach it. The job is emptying and purging on the spot.
A moment's running, or just your ignition on. Once primed, the system has drawn petrol from the tank up to the fuel filter and the fuel lines. That is generally still a straightforward task — a drain, a flush, and the filter seen to.
Driven a couple of miles. Now the pump has spent these miles labouring on thinned fuel. Miles is only half of it; how hard it was driven counts just as much. Either way the work includes that tank, your lines, your filter and clean fuel through the entire circuit. Short trips, like the school run to the local primary school, are one thing. Very different again: a run to Swansea, under 10 miles away, or any miles on the M4, under a mile from Shelone, where the motor never stopped working hard.
Driven on till it complained — clattering, smoke, a lumpy idle, a soft throttle. That's your engine telling you its fuel has stopped acting like diesel. Pull up wherever you are — the verge on Margaret's Close, a lay-by, a side street — then leave the vehicle there. Lasting damage is very unusual if a car is pulled over early, and the fuel drain and flush that still come first deal with it.
What Shelone motorists get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mix. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice presumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through smaller parts: that's how a current diesel handles its fuel, so the lubrication counts more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there is no harm done." Feed diesel to a petrol motor and it usually won't run, so the motorist stops — and the harm stops with them. A diesel fed petrol normally starts, ticks over and drives away as though nothing has happened, whilst the pump wears. Running is not the same as fine.
An outdated fix for a different issue is behind this one. Myth: "Add some two-stroke oil and drive it home." It does not put back what petrol has weakened, and the petrol is still inside the tank later.
Once the engine has been run, part of the petrol sits in your filter and your lines, not the tank — and the next start pulls it right back through your pump. So the myth "drain your tank yourself and you're sorted" does not stand up. It is also truly hazardous to drain petrol into a can at the roadside.
How does petrol in a diesel take place?
It's rarely carelessness, and no one does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol car. That's how the forecourt makes it easy.
The moment routine stops matching your car is the moment it occurs. Any vehicle that's new to you — hired, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A hurried fill on the way to Briton Ferry with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Passat in front of you on the forecourt for its first tank — that's when. With rain, a call arriving, or children to deal with, the hand simply does what it has always done.
How to avoid petrol in a diesel on your next fill-up in Shelone
- The label is what matters, so read the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Inspect your filler flap. Plenty of cars state the fuel type inside the flap or on the cap. Look at it on the first fill in a car you don't know.
- One of each in the household? Label the key to the diesel — a coloured fob, a sticker — because intending to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It sounds silly. It works.
- While 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 come with a filler designed to reject a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop reading the pump.
- Stop as soon as you notice. Less petrol inside that tank makes a thinner mixture. It doesn't change what to do next, which is still not to crank it.
Already put petrol in a diesel in Shelone?
The order of things is brief, then. Do not switch your ignition on, and do not crank it. If you're still on the forecourt — Texaco or anywhere else — ask the staff to help you push it clear of the pump. Call 0333 366 0103 next, with three facts — the fuel, the rough amount, and whether it's run.
Corrosion and deposits are the problem with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and see its own Shelone page.
Shelone petrol in a diesel tasks: why one costs more than another
Four separate tasks lie behind the four situations above — which is why there is no fair single quote. The scenario itself does most of the work of moving the cost. Two things follow that: the petrol that went in as a share of what your tank holds, then the place your car is in and whether a technician can reach it safely.
Before any quote, not after, we ask three questions: the fuel that was put in, its quantity, and if it has run. That's why. The replies turn a range into a straight figure.
About Shelone and its setting
Shelone is a coastal suburban area in Neath Port Talbot, situated near the city of Swansea. Shelone sits at a low elevation of around 15 metres, looking out towards the sea. Shelone is characterized by its predominantly terraced housing stock, typical of many Welsh coastal towns. Shelone is close to nearby places such as Warren Hill and Giants Grave, and is within easy reach of Briton Ferry.
Fuel drain cover across Neath Port Talbot, Shelone included
Warren Hill, Giants Grave and Briton Ferry are among the places near Shelone that the same vans work, answering petrol in diesel jobs across Shelone's SA postcode area. The vehicle doesn't need to come to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Shelone: still at the pump?
The best position there is, then — that's where you are. Call, and keep it switched off.