Acrefair: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — as long as no one has started it. Until the ignition primes the pump, your starter turns, or the car is driven, petrol in a diesel tank just waits there and does nothing. Which means the truthful reply to that first Acrefair question — "have I wrecked it?" — usually no. To leave the car that way, call Petrol in Diesel and leave the motor alone. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and ways to make sure you never repeat it.
Inside the motor: what petrol in a diesel does
Diesel has two tasks on its way through a motor. Before it combusts, it protects — then it burns. Very fine clearances are built into the injectors and your high-pressure pump, and only your diesel flowing through stops their surfaces grinding together.
Petrol does the first job poorly and the second not at all. It's runnier than diesel and strips away the protection the fuel system hinges on, so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the clattering comes from.
Put these together and the shape of the trouble is plain. The damage is done by movement, not by contact. Petrol in a tank is a fuel fault. 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 your fuel to your injectors further on.
How serious is petrol in a diesel? Four situations we see in Acrefair
Fuelled, and not started: no case is better. At a forecourt, and really only there, the petrol is still confined to your tank — since everywhere else the car was driven to reach it. The job is emptying and flushing on the spot.
Started for a second, or only your ignition on. With your system primed, the lines and filter now contain petrol that came from that tank. Drain, flush, deal with your filter: still usually simple.
A couple of miles driven, and the pump has spent every one of them labouring on thinned fuel. How hard the vehicle was driven matters as much as how far, and this work takes in your tank, the fuel lines, the fuel filter and clean fuel through the whole system. Short trips, like the school run to Weston Rhyn Primary School, are one thing. Getting as far as Wrexham, under 10 miles away, makes a very different task — as does any miles on the M53, under 25 miles from Acrefair, with the engine working hard all the way.
Driven till it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your engine signalling fuel that no longer runs like diesel. Stop where you are — on the verge on Tref Y Nant Park, at the kerb, down a side road — and don't move it again. What comes first is still the fuel drain and flush, and that sorts it out, with permanent damage very rare if a vehicle is pulled over soon.
Acrefair motorists and that petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a fuller tank of the same mix. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A current diesel runs its fuel through finer parts at higher pressure, which makes the lubrication count more, not less.
"It starts, it drives, so there is no harm" — the myth that trips up most people than any other. A petrol engine fed diesel generally will not run, and so the driver stops and the damage stops with them. Feed petrol to a diesel and it generally starts, ticks over and pulls away as if nothing happened — all the while its pump is wearing. A running engine does not mean fine.
An old fix for a different fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." That petrol is still in that tank after that, and what it has weakened isn't put back.
Myth: "Drain your tank yourself and you are sorted." After your engine has run, some of the petrol is no longer in your tank: it is in the filter and the lines, and it goes straight back through the pump at your next start. It's also truly hazardous to drain petrol into a can by the roadside.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Seldom, if ever. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol vehicle. That is how the forecourt makes it simple.
When routine and the car stop matching, it happens. Courtesy car, hire car, or a vehicle that is brand new. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Fuelling up in a rush on the way to Ruabon, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it occurs. Add a back seat full of kids, a phone call or rain, and habit takes over.
How to avoid petrol in a diesel on your next fill-up in Acrefair
- The label is what matters, and so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Check the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in any motor you don't know.
- Mark your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud 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, and so put the phone away and keep your mind on the pump.
- Some diesels have a filler designed to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- Stop the moment you realise. Less petrol inside your tank means a weaker blend. It doesn't change what to do next, which is still not to start the vehicle.
Put petrol in a diesel around Acrefair already?
The order of things is brief, then. Leave it unstarted, with the ignition off as well. If you are still at the forecourt — Shell or anywhere else — ask the attendants to help you roll the car away from the petrol pump. What got in, roughly how much, and if it has run: tell us that when you ring 0333 366 0103.
Corrosion and deposits form the issue with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Acrefair page.
Why one petrol in a diesel job around Acrefair costs more than another
Four different tasks lie behind the four situations above — which is why there is no honest single quote. What shifts your cost is mostly which of them you are in. Next it is the ratio — how much petrol was put in against how much that tank takes — and after that where the car is and whether our van can get to it safely.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. Those answers change a range into a straight figure.
About Acrefair
Acrefair is a village situated on the banks of a river in Wrexham county, with a mix of semi-detached housing and other residential properties. Acrefair sits at an elevation of 113 metres, close to the nearby settlements of Aber-nant, Pont Cysyllte, and Trevor. Acrefair is located near the city of Wrexham, approximately 5.9 miles away, and is part of the wider Welsh countryside. Acrefair has a population of around 918 people, living in a variety of housing types, predominantly semi-detached homes.
Fuel drain cover around Acrefair and across Wrexham
Petrol in diesel call-outs in Acrefair — part of the LL postcode area — go to vans that also cover the spots around it, Aber-nant, Pont Cysyllte and Trevor included. We drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Acrefair: still at the pump?
No position is better: that's where you are. Turned off it stays; then call.