Alton: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely feel. Till your ignition primes the pump, the starter turns, or your vehicle is driven, petrol in a diesel tank simply rests there and does nothing. Which means the truthful reply to the first Alton query — "have I wrecked it?" — normally no. Leave the motor off then ring Petrol in Diesel — that is how you keep it like that. What petrol actually does to a diesel, how to gauge how far it's travelled, and how to keep it from happening a second time: that's the remainder of this page.
Inside your engine: what petrol in a diesel does
Diesel has two jobs on its way through a motor. It protects to begin with, and after that does it burn. What keeps the surfaces inside your high-pressure pump and the fuel injectors from wearing down against each other is the diesel flowing through them — they are made to extremely fine gaps.
The second job petrol doesn't do at all, and the first it does badly. A pump running on a petrol blend is wearing itself out, since 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 opposite of what a diesel needs from its fuel — and that's where any rattling comes.
The shape of the issue is clear when you put those together. It is movement that does the harm, not contact. Where that petrol is only in the tank, it's a fault of fuel, nothing more. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has been working on that petrol is where a mechanical fault starts.
How bad is petrol in a diesel? Four situations our technicians see in Alton
Fuelled but never started — the best it gets. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held in that tank alone, it is cleared and flushed right where it stands, and nothing more is needed.
Started for a second, or just your ignition on. The fuel system has been bled, and so petrol has left that tank and reached your filter and the lines. Drain, flush, see to your filter: still normally easy.
Those few miles on the road were the pump running on fuel weakened by petrol the whole way. Tank, lines, filter, then fresh fuel run through the entire circuit: that's the work, and the way your car was driven counts as much as the distance. Short trips, like the school run to St Peter's CofE Academy Alton, are one thing. A run as far as Stoke-on-Trent, under 15 miles away, is a very different job. So is any miles on the M6, under 15 miles from Alton, where your engine has been working hard throughout.
Driven till it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. That's your engine telling you its fuel no longer is behaving like diesel. Stop where you are — on the verge on Smithy Bank, at the kerb, down a side road — and do not move it again. What comes first is still the fuel drain and flush-through, and that deals with it, with lasting damage very rare when a vehicle is pulled over quickly.
What Alton people get told about petrol in a diesel — and the stories 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're left with a bigger tank, still the same mixture. Percentage is not how a diesel fuel system copes with petrol, whatever that advice presumes.
Not so: a current diesel copes with a bit of petrol. Rather, the opposite. At higher pressure, through more precise parts: that is how a current diesel moves its fuel, so the protection matters for more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools motorists. Diesel in a petrol motor usually means a motor that will not run: the driver stops, and so does the damage. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, while your pump grinds. Fine and running aren't the same at all.
An outdated workaround for a distinct issue is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." What petrol has thinned remains weakened, and that petrol stays in your tank regardless.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol lies in your filter and lines, ready to go right back through the pump at the next start. Besides, petrol drained into a can by the road is truly hazardous.
Why petrol in a diesel occurs at all
No one does it on purpose, and it's seldom carelessness. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it simple, and the error runs one way.
When habit and the vehicle stop matching, it takes place. Courtesy car, hire car, or a car that's brand new. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. A hurried fill on the way to Uttoxeter with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
How to avoid petrol in a diesel at your next fill-up around Alton
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- Check your filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in a car you don't know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, in a house with one of each.
- It seems silly and it works: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- While you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Noticing it mid-fill? Stop at once. A thinner mix follows from less petrol in your tank, but the next stage remains the same: do not start the car.
Put petrol in a diesel in Alton already?
The order of things is brief, then. Don't fire it up, and do not turn your ignition on. Still at the forecourt, at the nearest petrol station or anywhere else? Ask the attendants to help you push the vehicle clear of the petrol pump. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
Corrosion and deposits form the issue with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and read its own Alton page.
One petrol in a diesel job around Alton costs more than another. Why?
An honest single price does not exist here: four situations, four separate tasks. Mostly, the cost shifts with which situation you are in. Next it's the proportion — how much petrol got in against how much that tank takes — and then where the car is and whether a technician can reach it safely.
Ahead of any quote, not after, we ask three queries: your fuel that was put in, its quantity, and whether it's run. That is why. Those replies are what change a range into one firm number.
About Alton itself
Alton is a village in Staffordshire, situated on the riverside in the West Midlands region. Alton sits at an elevation of 149 metres, with detached housing being the predominant type of accommodation. Alton is located near several other small settlements, including Tithebarn, Rakes Dale, and Hansley Cross, and is approximately 12 miles from Stoke-on-Trent. Alton has a population of around 980 residents.
Across Staffordshire and in Alton: fuel drain cover
Our vans answering petrol in diesel call-outs in Alton, in the ST postcode area, also work the places around it, Tithebarn, Rakes Dale and Hansley Cross included. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots we work, and the car doesn't need to come to us.
Still at the pump in Alton?
The best place there is, then — that's where you are. Switched off it remains; then phone.