Horsley Hill: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you likely feel. Until the ignition primes your pump, your starter turns, or the vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which means the honest reply to the first Horsley Hill question — "have I wrecked it?" — normally no. To keep the vehicle that way, phone Petrol in Diesel then leave your motor switched off. 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.
Petrol in a diesel: what does it do to your engine?
Two jobs fall to diesel on its journey round a motor. It protects to begin with, and after that does it burn. Your high-pressure pump and your injectors are made to extremely fine gaps, and your diesel passing through them is what stops those surfaces from wearing against each other.
Petrol handles the first job poorly and the second not at all. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the protection your fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where the rattling starts.
Together, those leave the shape of the issue plain. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into the fuel injectors further along, which is why a pump that has been working on the petrol is where a mechanical issue starts.
How bad is petrol in a diesel? Four situations our engineers see around Horsley Hill
The best case there can be: filled up, never started. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With that petrol kept inside your tank alone, it is drained and purged right where it stands, and nothing more is needed.
Started for a moment, or just the ignition on. Petrol has come out of that tank and got to your filter and the lines, because the system has been primed. Still generally easy: drain, flush, and the filter sorted.
Driven a couple of miles. Now the pump has spent these miles running on weakened fuel. The work is your tank, the lines, the fuel filter and clean fuel through the entire system, and how hard your car was driven counts as much as how far. The school run to St Gregory's Catholic Primary School, South Shields is one matter. A run as far as Sunderland, under 10 miles away, is a very different task. So is any mileage on the A194(M), under 10 miles from Horsley Hill, where the engine has been running hard throughout.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is your motor signalling fuel that no longer behaves like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Cheviot Road. A vehicle pulled over quickly very rarely has lasting damage, because the drain and the flush-through, which still go first, take care of it.
What Horsley Hill people get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. A diesel fuel system doesn't tolerate petrol by percentage in the way that advice assumes.
Myth: a newer diesel copes with a bit of petrol. Rather, the opposite. At higher pressure, through finer components: that is how a current diesel moves its fuel, and so the protection matters for more, not less.
This is the one that fools people. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol motor and it generally will not run, and so the driver stops — and the harm stops with them. Feed petrol to a diesel and it generally fires up, ticks over and pulls away as if nothing happened — all while its pump is wearing. Being able to run is not proof of being fine.
An outdated workaround for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has diluted, and the petrol is still inside that tank afterwards.
Myth: "Drain the tank yourself and you are sorted." After the motor has run, some of the petrol is no longer in that tank: it's in the filter and your lines, and it goes straight back through the pump on the next start. Draining petrol into a can by the roadside is also genuinely dangerous.
Why petrol in a diesel takes place at all
On purpose? Never. Through carelessness? Seldom, if ever. 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 motor at all. The forecourt makes it easy, and the error runs one way.
When routine and your car stop matching, it takes place. A new vehicle, a hire car or a courtesy car. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A hurried fill en route to East Boldon with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: precisely when it happens. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
How to prevent petrol in a diesel at your next fill-up in Horsley Hill
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- The first fill in a new vehicle is the time to check your filler flap — inside it, or on the cap, plenty of cars state the fuel to use.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, for a home with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new motor, say "diesel" aloud. Daft, perhaps, but it works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels come with a filler built to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- The moment you realise, stop: less petrol inside your tank means a weaker mix. What to do next does not change, though — still don't crank it.
Horsley Hill: already put petrol in a diesel?
Then the order of things is short. Starting it is out, and so is switching on the ignition. Yet on the forecourt, at Gulf or anywhere else? Ask the attendants to help you roll the vehicle clear of the petrol pump. Ring 0333 366 0103 next, with three answers — your fuel, the rough quantity, and if it has run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Horsley Hill page.
What makes one Horsley Hill petrol in a diesel task cost more than the next
An honest single price does not exist here: four scenarios, four separate tasks. What moves your cost is mostly which of them you are in. After that it's the ratio — how much petrol got in against how much your tank holds — and after that where your car is and whether our van can reach it safely.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and this is the reason. Their replies are what turn a range into one firm number.
About Horsley Hill itself
Horsley Hill is a suburban area in Tyne and Wear, situated near the coast and approximately 5.6 miles from Sunderland. Horsley Hill has a relatively low elevation of 29 metres and is characterized by semi-detached housing. Horsley Hill is part of a larger urban landscape that includes nearby places such as Harton, Cauldwell, and Harton Nook.
Horsley Hill and Tyne and Wear: where our fuel drain cover reaches
Horsley Hill rests in the NE postcode area, and our teams that answer petrol in diesel calls there work the spots around it as well — Harton, Cauldwell and Harton Nook among them. A forecourt, a supermarket car park, a lay-by or your own drive are all spots we work, and your vehicle does not need to move to us.
Still at the petrol pump around Horsley Hill?
Nothing beats it: that is where you are. Leave the vehicle switched off, then ring.