How Worried Should You Be? Petrol in a Diesel Car in Pennymoor
Not started? Then less worried than you probably are. "Have I ruined it?" is the first question anyone in Pennymoor asks, and the honest answer is normally no, because petrol left in a diesel tank harms nothing till it is drawn through your fuel system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to phone, with the engine kept off, and so it remains that way. The rest of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what goes on
Diesel does two tasks on its way through an engine. Lubricating comes before burning; it does both. Very fine tolerances are built into the fuel injectors and the high-pressure fuel pump, and just your diesel running through keeps their surfaces from grinding together.
The second job petrol does not do at all, and the first it does badly. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on that mixture wearing itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the rattling.
Seen together, they show what shape the trouble takes. It's movement that causes the damage, not contact. Any tank with petrol in it is a fuel issue. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors beyond it.
Four scenarios our technicians see in Pennymoor: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol held in that tank alone, it is cleared and purged right where it stands, and nothing more is needed.
The ignition turned on, or a brief start. Once primed, the system has pulled petrol out of your tank as far as the fuel filter and your lines. Usually nothing more than emptying, purging and seeing to your filter, so still straightforward.
Your pump has worked a few miles on thinned fuel — that's what driving the car does. Miles is only half of that; how hard it was driven counts equally. Either way the work runs to your tank, the fuel lines, the fuel filter and fresh fuel through the entire system. On the school run to Cheriton Fitzpaine Primary School, the distance is small. Any distance on the M5, under 10 miles from Pennymoor, means the engine has worked hard throughout, and a run to Exeter, under 15 miles away, makes a very different task too.
Driven until it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your engine reporting fuel that no longer runs like diesel. Stop where you are — on the verge on North Road, at the kerb, down a side road — and do not move it. Permanent damage is very rare when a car is stopped soon, and the drain and flush-through that still come first deal with it.
Myths Pennymoor motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage is not how a diesel fuel system copes with petrol, whatever that guidance assumes.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." Smaller components and higher pressure are the way a modern diesel runs its fuel, and that makes the protection count more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up most drivers than any other. Any petrol engine fed diesel usually won't run, and so the motorist stops and the harm stops with them. While your pump wears, a diesel fed petrol usually starts, idles and drives away as though nothing has happened. Running isn't the same as fine.
Myth: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another fault. It doesn't put back what petrol has weakened, and the petrol is still in that tank later.
The next start sends petrol back round your pump from the lines and the fuel filter, where some of that ends up once the engine has run. That is why draining the tank yourself doesn't leave you sorted — a myth. On top of that, petrol drained into a can by the road is genuinely dangerous.
How it happens: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it simple.
It takes place when habit and the vehicle stop matching. A vehicle that is new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the driveway. Your ordinary forecourt, its pumps now in a different order. A hurried fill en route to Crediton with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist used to petrol: precisely when it occurs. Add a back seat full of kids, a phone call or rain, and habit takes over.
Avoiding petrol in a diesel next time you fill up around Pennymoor
- The label is what matters, and so read the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Plenty of cars state the fuel type inside the filler flap or on the cap, and so check it on your first fill in any vehicle you do not know.
- Label the 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.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new motor, say "diesel" aloud. Daft, yes, but it does the trick.
- While you're thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Add-on devices exist for motors without one, and some diesels are built with a filler that won't accept a petrol nozzle. Useful — but a safety net only, never a reason to stop checking the label.
- The moment you realise, stop: less petrol inside the tank means a weaker mixture. What to do next does not change, though — still don't start the car.
Already put petrol in a diesel in Pennymoor?
Then the order of things is short. Don't switch the ignition on, and do not fire it up. Ask the staff to help you push it away from the pump if you are still at the forecourt, whether that is the nearest petrol station or anywhere else. What got in, about how much, and whether it has run: tell us those when you call 0333 366 0103.
Corrosion and deposits are the issue with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and see its own Pennymoor page.
What makes one Pennymoor petrol in a diesel job cost more than the next
There's no honest single price for this, because the four situations above are four different tasks. Which of them you are in is chiefly what shifts your cost. The share counts next, meaning how much of the tank is petrol, and then the location of the vehicle and whether getting to it is safe for a technician.
Three queries come first, before quoting, instead of after — what was put in, how much, has it run — and that is the reason. Those replies are what turn a range into one firm number.
About Pennymoor, for a moment
Pennymoor is a small village in inland Devon, situated approximately 12 miles north of Exeter and 157 miles west of London. Pennymoor sits at an elevation of 239 metres, surrounded by rolling countryside and nearby villages such as Cruwys Morchard and Poughill. Pennymoor is characterised by its predominantly detached housing stock, reflecting its rural setting. Pennymoor has a population of around 535 residents, making it a tight-knit community.
Pennymoor and Devon: where our fuel drain cover runs
Pennymoor sits in the EX postcode area, and the vans that answer petrol in diesel calls there work the locations around it as well — Cruwys Morchard, Way Village and Poughill among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
Still at the pump in Pennymoor?
The best position there is, then — that's where you are. Keep it off. Call.