How Worried Should You Be? Petrol in a Diesel Car in Tyburn
Not started? Then less anxious than you likely are. Till the ignition primes the pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which makes the honest reply to that first Tyburn query — "have I wrecked it?" — normally no. Leave your engine off then call Petrol in Diesel — that is how you keep it like that. The rest of this page explains what petrol really does to a diesel, how to tell 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 happens
Passing through an engine, diesel does two jobs at once. Lubricating comes before burning; it does both. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing down against one another is the diesel passing through them — they're built to very fine gaps.
Petrol handles the first job poorly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump on the mixture to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the clattering.
The shape of the issue is plain when you put those together. It's movement that causes the harm, not contact. Where that petrol is only inside your tank, it is a fault of fuel, nothing more. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with your fuel to the fuel injectors further on.
Tyburn, petrol in a diesel: four cases, from mild to major
Filled but not once started — as good as it gets. Only that tank has petrol in it, so the job is draining the tank and flushing the fuel system where the vehicle sits. This situation can only really happen on a forecourt: anywhere else, the car got there by being driven.
Started for a second, or just the ignition on. Once primed, your system has drawn petrol from your tank up to your filter and the fuel lines. Normally little more than clearing, purging and seeing to your filter, so still easy.
Driven a couple of miles. Now your pump has spent these miles running on diluted fuel. The work is the tank, the lines, the filter and clean fuel through the entire system, and how hard your car was driven matters as much as how far. On the school run to Gunter Primary School, the miles is small. A run as far as Birmingham, under 10 miles away, is a very different task. So is any miles on the M6, under 3 miles from Tyburn, where your engine has been running hard the whole time.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the motor reporting fuel that no longer behaves like diesel. Whether it is the verge on Elmfield Avenue, a lay-by or a side road, stop where you are then leave it. A vehicle pulled over early very seldom has permanent damage, as the drain and the flush-through, which still go first, sort it out.
Petrol in a diesel myths Tyburn people hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance presumes.
If anything, the opposite is true. Myth: "A newer diesel can cope with a bit of petrol." Smaller components and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication matter more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel normally stops, because it will not run, and the harm stops there. Feed petrol to a diesel and it generally starts, idles and pulls away like nothing has happened — all while its pump is wearing. Being able to run is not proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct issue. What petrol has thinned remains thinned, and that petrol remains in that tank anyway.
The next start sends petrol back round the pump out of the lines and the filter, where some of it ends up once the engine has run. That's why draining your tank yourself doesn't leave you sorted — a myth. Also, a can of petrol drained by the roadside is genuinely hazardous.
Why petrol in a diesel occurs at all
It is seldom carelessness, and no one does it on purpose. A diesel nozzle generally will not fit a petrol vehicle, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in one direction.
The moment habit stops matching the vehicle is the moment it occurs. Hire cars, courtesy cars, and motors that are new to you. Two vehicles on one driveway, one petrol, one diesel. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Chester Road. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
How to avoid petrol in a diesel at your next fill-up in Tyburn
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is just a hint.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — inside it, or on the cap, plenty of motors state which fuel to use.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, for a house with one of each.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It seems silly. It works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available for the remainder. Count it as a safety net, then keep checking the petrol pump.
- Noticing it halfway? Stop there and then. A thinner mixture follows from less petrol inside your tank, but the next step remains the same: do not crank it.
Petrol already in a diesel around Tyburn? Start here
The order of things is short, then. Never start the vehicle, and do not turn the ignition on. Still on the forecourt, at Shell or anywhere else? Ask the attendants to help you roll the vehicle clear of the pump. What was put in, roughly how much, and whether it's run: tell us those when you ring 0333 366 0103.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and see its own Tyburn page.
One petrol in a diesel task around Tyburn costs more than another. Why?
A fair single price doesn't exist here: four scenarios, four separate jobs. The situation itself does most of the work of moving the cost. The proportion counts next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for a technician.
That is why we ask three queries before costing instead of after: what was put in, how much, and if it has run. Those replies change a range into a straight figure.
About Tyburn and its setting
Tyburn is a suburban area in the West Midlands, situated near the River Tame and close to the city of Birmingham. Tyburn has a mix of housing types, but semi-detached homes are the most common, and its population is around 4136 people. Tyburn is located near other suburban areas such as Pype Hayes and Castle Vale, and is connected to the city centre by Chester Road. Tyburn sits at an elevation of 104 metres above sea level, in a gently sloping riverside setting.
Fuel drain cover across West Midlands, Tyburn included
Pype Hayes, Castle Vale and Chester Road are among the spots around Tyburn that the same teams work, answering petrol in diesel call-outs across Tyburn's B postcode area. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
In Tyburn and still at the pump?
Then you are in the best position there is. Keep it off. Call.