How Worried Should You Be? Petrol in a Diesel Car in Pennyland
Far less than you likely are, if it hasn't been started. Till your ignition primes the pump, your starter turns, or the vehicle is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the truthful reply to that first Pennyland question — "have I wrecked it?" — normally no. Leave the engine off then call Petrol in Diesel — that keeps it like that. What petrol really does to a diesel, how to judge how far it's travelled, and how to keep it from happening a second time: that is the rest of this page.
What petrol in a diesel does to your engine
Two tasks fall to diesel on its journey through a motor. Lubricating comes before burning; it does both. Extremely fine tolerances go into the fuel injectors and the high-pressure pump, and just your diesel flowing through stops their surfaces grinding together.
Of those two jobs, petrol handles the first poorly and the second never. It is thinner than diesel and removes the protection the fuel system rests on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from.
Combined, those make the shape of the trouble plain. Not contact but movement is what does the harm. All a tank with petrol in it amounts to is a fuel problem. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors beyond it.
How serious is petrol in a diesel? Four scenarios our engineers see in Pennyland
Fuelled, and never started: no case is better. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol kept inside that tank alone, it's emptied and cleaned on the spot, and nothing more is needed.
A brief spell of running, or merely your ignition on. The fuel system has been bled, so petrol has left the tank and reached the filter and your lines. Drain, flush, see to your filter: still usually straightforward.
Those few miles on the road were your pump labouring on fuel thinned by petrol throughout. How hard the vehicle was driven counts as much as how far, and the work covers your tank, your lines, the fuel filter and clean fuel through the whole system. The school run to Brooksward School is one matter. A run as far as Milton Keynes, under 3 miles away, is a very different task. So is any miles on the M1, under 3 miles from Pennyland, where your engine has been running hard throughout.
Driven on until it complained — knocking, smoke, a lumpy idle, a dead throttle. The motor is telling you your fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Colesbourne Drive, a lay-by, a side street — then leave the car there. The fuel drain and flush still go first, and they take care of it: if a car is stopped early, long-term damage is very unusual.
Stories Pennyland drivers hear about petrol in a diesel
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 are left with a fuller tank, still the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that guidance presumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the opposite. A newer diesel runs its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
"It starts, it drives, so no harm done" — the myth that catches most motorists than any other. Feed diesel to a petrol engine and it normally won't run, and so the motorist stops — and the harm stops with them. While the pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Being able to run isn't the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct problem. The petrol is still in the tank after that, and what it has diluted is not put back.
Myth: "Drain your tank yourself and you're sorted." Once your engine has run, some of that petrol is no longer inside the tank: it is in your filter and the fuel lines, and it goes right back through your pump at the next start. On top of that, petrol cleared into a can by the road is truly hazardous.
How it happens: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. A diesel nozzle generally won't fit a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake simple, and only in one direction.
The moment routine stops matching the vehicle is the moment it happens. Courtesy car, hire car, or a car that's brand new. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps arranged differently. A train to catch, and a rushed fill en route to Milton Keynes Central. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: precisely when it takes place. With rain, a call coming in, or a car full of children to deal with, your hand just does what it always has.
Avoiding petrol in a diesel next time you fill up around Pennyland
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the pump's label; the colour is only a clue.
- Many vehicles state the fuel inside your filler flap or on the cap, so check there on your first fill in a vehicle you do not know.
- One of each in the house? Mark your key to the diesel — a bright fob, a sticker — since meaning to remember is not enough.
- "Diesel", aloud, before you lift the nozzle — every time a new or hired car gets its first tank. It seems silly. It works.
- Mistakes like this are simple to make whilst your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for the remainder. Count it as a backstop, then keep reading the petrol pump.
- The moment you notice, stop: less petrol in the tank makes a thinner mix. What to do next doesn't change, though — still don't start the car.
Pennyland: already put petrol in a diesel?
Short and simple, then, is the order of things. Do not turn your ignition on, and do not crank it. Still at the forecourt, at Esso or anywhere else? Ask the staff to help you roll it away from the petrol pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
If it was AdBlue rather than petrol, say so. That is a different issue — corrosion and deposits and not lost lubrication — and it has its own page for Pennyland.
Why one petrol in a diesel job around Pennyland costs more than another
There's no fair single quote for this, since the four situations above are four separate jobs. Which of them you're in is mostly what shifts the cost. Where the vehicle is counts too, and whether our van can safely reach it, after the proportion of petrol to what the tank takes.
What got in, how much, and if it has run — three queries our technicians ask before quoting, not after, for exactly that reason. Those replies are what turn a range into one firm number.
About Pennyland itself
Pennyland is a suburban area located on the outskirts of Milton Keynes in Buckinghamshire, situated near the riverside at an elevation of 79 metres. Pennyland sits close to several nearby parks, including Downhead Park and Bolbeck Park, and is characterized by its predominantly detached housing stock. Pennyland is also near Downs Barn, and its residents are approximately 46 miles from London. Pennyland has a population of around 6103 people.
Fuel drain cover across Buckinghamshire, Pennyland included
Pennyland sits in the MK postcode area, and our teams that answer petrol in diesel calls there work the places near it as well — Downhead Park, Downs Barn and Bolbeck Park among them. No need to bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
At the pump around Pennyland, right now?
In that case, you could not be in a better position. Keep the car switched off, and ring.