How Worried Should You Be? Petrol in a Diesel Car in Gigg
Unstarted? Then less anxious than you probably feel. Petrol resting in a diesel tank does nothing to the motor until something draws it through the system — your ignition priming your pump, your starter, or driving itself. So the fair answer to the first query everyone in Gigg asks, "have I ruined it?", is usually no. Leave the engine off and ring Petrol in Diesel — that is how you keep it like that. The rest of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you a second time.
Your engine and petrol in a diesel: what happens
Passing through an engine, diesel does two jobs at the same time. It ignites, and before it combusts it lubricates. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing down against one another is your diesel flowing through them — they're built to very fine clearances.
Petrol does the first job poorly and the second not at all. The rattling comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system rests on, and any pump running on that mixture is wearing itself.
Taken together, they show what shape the issue has. The damage is done by movement, not by contact. Where that petrol is only in the tank, it is a fault of fuel, nothing more. After your pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that's grinding is carried onward to the injectors with your fuel.
How serious is petrol in a diesel? Four situations our engineers see in Gigg
Fuelled but not once started — as good as it gets. Only the tank has petrol in it, and so the task is draining your tank and purging the fuel system where the car stands. This scenario can only truly happen at a forecourt: anywhere else, the car got there by being driven.
Your ignition switched on, or a short start. The fuel system has been bled, so petrol has left your tank and reached your filter and the lines. Drain, flush, see to your filter: still normally straightforward.
Your pump has worked a couple of miles on weakened fuel — that is what driving it meant. The work is your tank, the fuel lines, the fuel filter and fresh fuel through the entire circuit, and how hard the car was driven matters as much as how far. The school run to St Luke's CofE Primary School is one thing. Getting as far as Salford, under 10 miles away, makes a very different job — as does any miles on the M66, under a mile from Gigg, with the motor running hard all the way.
Driven on until it complained — rattling, smoke, an uneven idle, a dead throttle. The engine is telling you the fuel is no longer acting like diesel. Stop where you are — on the verge on Redmere Drive, at the kerb, down a side road — and do not move it. The fuel drain and flush still go first, and they sort it out: when a car is pulled over quickly, permanent damage is very rare.
What Gigg motorists get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. A bigger tank of the same mixture is all you get, since topping up removes nothing. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the opposite holds. Myth: "A modern diesel can cope with a bit of petrol." Protection matters more on newer diesels, not less, because their fuel runs through finer parts at higher pressure.
"It starts, it drives, so no harm done" — the myth that catches more drivers than any other. Any petrol engine fed diesel generally will not run, and so the motorist stops and the harm stops with them. Feed petrol to a diesel and it generally fires up, idles and drives away like nothing has happened — all the while its pump is wearing. Being able to run isn't proof of being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, supposed for another fault. None of what petrol diluted is put back by it — and afterwards, that tank still holds the petrol.
Myth: "Drain that tank yourself and you are sorted." Once the motor has been run, some of the petrol is no longer in your tank: it's in your filter and the lines, and it goes straight back through the pump at the next start. And, a can of petrol filled by the kerbside is truly hazardous.
How it happens: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol car at all. The forecourt makes it simple, and the slip runs one way.
When habit and the car stop matching, it takes place. Courtesy car, hire car, or a vehicle that is new. Two motors on one driveway, one petrol, one diesel. A familiar forecourt with the pumps in a different order. Filling up in a rush en route to Castleton, with a train to catch. Precisely the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Throw in a back seat full of kids, a phone call or rain, and habit wins.
Next time you fill up in Gigg: preventing petrol in a diesel
- Green for unleaded and black for diesel is usual in the UK — but not on every forecourt. Trust the label on the petrol pump, not the colour.
- Check the filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on the first fill in any car you don't know.
- Label your key. In a home 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 fuel a hired or new vehicle, say "diesel" out loud. Daft, perhaps, yet 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 are available for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Noticing it halfway? Stop at once. A thinner mix follows from less petrol inside the tank, but the next step remains the same: don't fire it up.
Petrol already in a diesel around Gigg? Begin here
Then the order of things is brief. Starting it is out, and so is turning on the ignition. Yet at the forecourt, at Asda or anywhere else? Ask the staff to help you roll the vehicle away from the pump. Then ring 0333 366 0103 and tell us what went in, about how much, and if it has run.
Say so if it was AdBlue rather than petrol: it is a separate problem, with its own page for Gigg, since AdBlue brings corrosion and deposits instead of lost lubrication.
Gigg petrol in a diesel jobs: why one costs more than another
The four scenarios above are four different jobs, so no single price for this would be honest. The situation itself does most of the work of moving the cost. Next it is the share — how much petrol was put in against how much that tank holds — and after that where the vehicle is and whether our van can get to it safely.
Three questions come first, before quoting, rather than after — what got in, how much, has it run — and this is the reason. Given the replies, there is a straight figure rather than a range.
About Gigg, briefly
Gigg is a suburban area in Greater Manchester, situated on the riverside at an elevation of 72 metres. Gigg lies approximately 7 miles from Salford and is surrounded by nearby places such as Fishpool, Pimhole, and Fletcher Fold. Gigg has a population of around 4291 people and predominantly consists of semi-detached housing. Gigg is located in the North West region of England, about 169 miles from London.
Gigg and Greater Manchester: where our fuel drain cover reaches
Gigg waits in the BL postcode area, and the vans that answer petrol in diesel calls there work the places near it as well — Fishpool, Pimhole and Fletcher Fold among them. We drain wherever your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the petrol pump in Gigg?
Nothing beats it: that's where you now are. Turned off it remains; then call.