How Worried Should You Be? Petrol in a Diesel Car in Farringdon
Provided it has not been started, worry far less than you probably are. Everyone in Farringdon begins with "have I ruined it?", and the fair answer is normally no: petrol left in the tank of any diesel remains harmless until priming, cranking or driving pulls it into the system. Keep it like that: leave your engine off then phone Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it has gone, and how to stop it from happening again: that is the remainder of this page.
The engine and petrol in a diesel: what happens
Diesel does two tasks on its way through an engine. Lubricating comes before burning; it does both. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing against one another is the diesel flowing through them — they're made to extremely fine clearances.
Of these two jobs, petrol handles the first poorly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump running on the blend to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the rattling.
Seen together, they make clear the shape the issue takes. It is circulation that causes the damage, not contact. All a tank with petrol in it amounts to is a fuel problem. After your pump has been working on that petrol, a mechanical issue has started: anything shed by a pump that is wearing is carried downstream to the fuel injectors with the fuel.
How serious is petrol in a diesel? Four scenarios our technicians see around Farringdon
Filled up, and never started: nothing beats it. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held in your tank alone, it's emptied and purged on the spot, and nothing more is needed.
The ignition turned on, or a brief start. Once primed, your system has drawn petrol from your tank up to the filter and the lines. Drain, flush, see to the fuel filter: still usually simple.
Your pump now spent a few miles on weakened fuel — that's what driving it does. Tank, lines, filter, then clean fuel run through the whole circuit: that's the work, and the way the vehicle was driven matters as much as the distance. Short trips, like the school run to St Peter and St Paul Catholic Primary School, are one thing. A run as far as London, under a mile away, is a very different job. So is any mileage on the M1, under 10 miles from Farringdon, where the engine has been labouring hard the whole time.
Driven on till it complained — knocking, smoke, a ragged idle, a soft throttle. What you are hearing is your engine signalling fuel that no longer behaves like diesel. Stop where you are — on the verge on Britton Street, at the kerb, down a side road — and don't move it. What comes first is still the drain and flush, and that sorts it out, with permanent damage very unusual if a car is stopped soon.
Petrol in a diesel stories Farringdon people hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed when you top up — that tank simply carries more of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, however much that advice presumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. A current diesel runs its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
The myth that catches people off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually will not run, and 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, as it usually will; meanwhile your pump grinds. Fine and running are not the same thing.
Myth: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another problem. None of what petrol thinned gets put back by it — and later, that tank still contains the petrol.
Once the motor has been run, part of the petrol sits in the filter and your lines, not that tank — and your next start pulls it straight back through your pump. So the myth "drain your tank yourself and you're sorted" does not stand up. It is also really dangerous to drain petrol into a can at the kerbside.
How it happens: petrol in a diesel
It's seldom carelessness, and nobody does it on purpose. A diesel nozzle mostly will not go into a petrol motor, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and just in that direction.
It happens when habit and your car stop matching. Hire cars, courtesy cars, and motors that are new to you. Two motors on one drive, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. Rushing for a train outside the nearest station and filling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed 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 kids.
Next time you fill up around Farringdon: preventing petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is only a clue.
- Check the filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a motor you don't know.
- Label your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- It sounds daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away then keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop reading the petrol pump.
- Spotting it mid-fill? Stop at once. A thinner mixture follows from less petrol inside that tank, yet your next stage stays the same: don't start it.
Farringdon: already put petrol in a diesel?
Then the order of things is brief. Don't fire it up, and do not turn your ignition on. Ask the attendants to help you push it away from the petrol pump if you are still on the forecourt, whether that is Texaco or anywhere else. Next, 0333 366 0103. We'll ask what was put in, about how much, and if it's been run.
If it was AdBlue and not petrol, say so. That is a separate problem — corrosion and deposits and not lost protection — and it has its own page for Farringdon.
One petrol in a diesel task around Farringdon costs more than another. Why?
Four different jobs lie behind the four situations above — which is why there is no honest single price. Which of them you are in is mostly what shifts the cost. Two things follow that: the petrol that got in as a share of what the tank takes, then the spot your car is in and whether a technician can get to it safely.
That is why our technicians ask three queries before pricing instead of after: what got in, how much, and if it's run. A range turns into a straight figure once the replies are in.
About Farringdon, briefly
Farringdon is a suburban area in central London, situated on the River Thames at an elevation of around 22 metres. Farringdon lies close to the neighbouring areas of Clerkenwell, Barbican, and St Lukes, and is characterized by a high proportion of flat dwellings. Farringdon is also a densely populated area, with a resident population of approximately 15,769 people. Farringdon's riverside location and proximity to the city centre make it a popular residential choice.
Farringdon and Greater London: where our fuel drain cover runs
Our vans answering petrol in diesel call-outs in Farringdon, in the EC1M postcode area, also work the locations near it, Clerkenwell, Barbican and St Lukes among them. You need not bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations where we work.
At the petrol pump around Farringdon, right now?
Then, you could not be in a better position. Turned off it stays; then call.