Should You Worry? Petrol in a Diesel Car in Filham
Probably less than you already are — as long as nobody has started the car. Everyone in Filham begins with "have I ruined it?", and the fair answer is generally no: petrol resting in that tank of a diesel remains harmless till priming, cranking or driving draws it into the system. Keep it that way: leave the motor off then call Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it's travelled, and how to keep it from happening again: that's the rest of this page.
Your engine and petrol in a diesel: what happens
Diesel does two tasks on its way through an engine. Before it combusts, it lubricates — then it burns. Extremely fine tolerances are built into your injectors and your high-pressure pump, and only your diesel flowing through stops those surfaces grinding together.
Petrol handles the first job poorly and the second not at all. It's thinner than diesel and takes away the protection the system hinges on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the rattling comes from.
The shape of the trouble is clear when you put those together. Contact doesn't do the harm — circulation does. Petrol in the tank is a fuel fault. Whatever a worn pump sheds goes on, borne by the fuel, into your injectors further along, which is why a pump that has been working on that petrol is where a mechanical fault starts.
Four scenarios our technicians see in Filham: how serious is petrol in a diesel?
Fuelled, and not started: no case is better. Being on a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held in that tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
Started for a second, or just your ignition on. With your system primed, the lines and filter already hold petrol that came from the tank. Drain, flush, see to the fuel filter: still normally straightforward.
Your pump now spent a few miles on thinned fuel — that's what driving the car does. How hard your car was driven matters as much as how far, and the work covers your tank, the lines, the filter and fresh fuel through the whole system. A school run to Stowford School is one thing. A run as far as Plymouth, under 15 miles away, is a very different task. So is any miles on the M5, under 50 miles from Filham, where the motor has been labouring hard the whole time.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. What you are hearing is the engine reporting fuel that no longer runs like diesel. Pull up on the spot — on the verge on Leyland Drive, at the kerb, down a side road — and don't move it. What goes first is still the drain and flush-through, and that sorts it out, with long-term damage very unusual if a car is pulled over early.
Myths Filham people hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mix is all you get, since topping up takes out nothing. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice supposes.
Myth: a current diesel copes with a bit of petrol. If anything, the opposite. A newer diesel sends its fuel through finer parts at higher pressure, which makes the lubrication count more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. A petrol engine fed diesel generally won't run, so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile your pump grinds. Fine and running aren't the same at all.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different fault. None of what petrol diluted is put back by it — and later, the tank still holds that petrol.
If the motor has been run, part of the petrol sits in your filter and the lines, not your tank — and your next start pulls it right back through the pump. So the myth "drain your tank yourself and you are sorted" does not hold. And, a can of petrol filled at the kerbside is genuinely risky.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol vehicle. That is how the forecourt makes it easy.
Routine and the car getting out of step is how it happens. A vehicle that's new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. Filling up in a hurry en route to Ivybridge, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it occurs. Add a back seat full of kids, a phone call or rain, and habit takes over.
Filham people: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is only a clue.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — inside it, or on the cap, many vehicles state which fuel to use.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a home with one of each.
- Before the nozzle comes off the pump the first time you fill a hired or new vehicle, say "diesel" out loud. Daft, yes, yet it works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the petrol pump.
- Less petrol makes a weaker mixture, so stop as soon as you realise — while remembering that the next stage is unchanged. It is still not to start the car.
Put petrol in a diesel in Filham already?
Then, there is only a short order of things. Do not start the car, and do not turn your ignition on. The staff at the forecourt — whether at BP itself or wherever you filled up — will normally help push it clear of the petrol pump if you ask. Next, 0333 366 0103. We'll ask what went in, about how much, and if it has been run.
Corrosion and deposits form the problem with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and see its own Filham page.
Why one petrol in a diesel job in Filham costs more than another
There's no honest single quote for this, since the four situations above are four separate tasks. Which of them you're in is mostly what moves your cost. Beyond that it's the ratio — how much petrol was put in against how much the tank holds — and then where your car is and whether a technician can reach it safely.
Before any quote, not after, come three queries: your fuel that was put in, the volume, and if it has run. That is why. The answers turn a range into a straight figure.
About Filham and where it is
Filham is a small hamlet in Devon, situated inland at an elevation of around 65 metres, approximately 10 miles north of Plymouth. Filham lies near the villages of Godwell and Ivybridge, and is part of a network of rural settlements in the South West region. Filham has a population of around 948 people, predominantly living in semi-detached housing. Filham is located about 181 miles west of London, making it a relatively remote community in southern England.
Fuel drain cover in Filham and across Devon
Godwell, Penquit and Ivybridge are among the spots near Filham that the same teams work, answering petrol in diesel calls across Filham's PL postcode area. Our technicians drain wherever your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Filham: still at the petrol pump?
Nothing beats it: that's where you now are. Keep it off. Phone.