How Worried Should You Be? Petrol in a Diesel Car in Hill
Unstarted? Then less worried than you probably are. Petrol resting in a diesel tank does nothing to your engine till something pulls it through the fuel system — the ignition priming the pump, your starter, or the drive itself. So the honest answer to the first query everyone around Hill asks, "have I ruined it?", is normally no. Keep it like that: leave your motor off then call Petrol in Diesel. Below, this page sets out what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel really does
Passing through a motor, diesel does two things at the same time. It burns, and before it burns it lubricates. Built to extremely fine tolerances, the fuel injectors and the pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Of those two jobs, petrol handles the first badly and the second not at all. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump running on the blend wearing itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the rattling.
Together, those make the shape of the issue plain. The harm is done by circulation, not by contact. A tank with petrol in it is a fuel problem. Whatever a worn pump sheds goes on, carried by your fuel, into the injectors downstream, which is why a pump that has been working on that petrol is where a mechanical fault begins.
Four scenarios we see around Hill: how serious is petrol in a diesel?
Filled up, and never started: nothing beats it. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in the tank alone, it is emptied and flushed right where it stands, and nothing more is needed.
Ignition on, or started for a second. Once primed, the system has drawn petrol from your tank up to your filter and the lines. Usually little more than clearing, cleaning and seeing to your filter, so still easy.
The pump now worked a few miles on weakened fuel — that's what driving the car meant. How hard your car 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. Short trips, such as the school run to Holmfirth Junior Infant and Nursery School, are one matter. Very different a second time: a run to Wakefield, under 15 miles away, or some miles on the M62, under 10 miles from Hill, where the engine kept running hard.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and your engine is saying so. Pull up where you are — on the verge on Hill, at the kerb, down a side road — and don't move it. Lasting damage is very uncommon when a car is pulled over early, and the drain and flush that still come first sort it out.
Hill motorists and that petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." Lubrication counts more on newer diesels, not less, since their fuel runs through smaller parts at higher pressure.
This is the one that fools drivers. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol motor and it generally will not run, so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and pulls away as if nothing has happened — all the while its pump wears. Being able to run isn't 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 problem. The petrol is still in your tank after that, and what it has diluted is not put back.
Once your engine has been run, part of that petrol is in your filter and the fuel lines, not that tank — and the next start pulls it straight back through your pump. So the myth "drain the tank yourself and you're sorted" doesn't hold. Also, a can of petrol drained by the roadside is truly hazardous.
Petrol in a diesel: how does it occur?
No one does it on purpose, and it's seldom carelessness. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol motor. That is how the forecourt makes it easy.
The moment routine stops matching your car is the moment it occurs. Courtesy car, hire car, or a motor that's new. Two vehicles on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Fuelling up in a rush en route to Brockholes, with a train to catch. Precisely the moment it happens: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. With rain, a call coming in, or a car full of children to deal with, the hand just does what it always has.
Preventing petrol in a diesel next time you fill up in Hill
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Read the pump's label; the colour is only a hint.
- Many vehicles state the fuel inside your filler flap or on the cap, and so check there on the first fill in a motor you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key if a household has one of each. So label it.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It seems daft and it does the trick.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the petrol pump.
- Noticing it mid-fill? Stop there and then. A thinner blend follows from less petrol in the tank, yet your next stage remains the same: don't fire it up.
Already put petrol in a diesel in Hill?
Short and simple, then, is the order of things. Do not turn the ignition on, and don't fire it up. Yet at the forecourt, at Murco or anywhere else? Ask the staff to help you roll it clear of the petrol pump. What went in, roughly how much, and whether it's run: tell us that when you phone 0333 366 0103.
If it was AdBlue instead of petrol, say so. That's a different issue — corrosion and deposits rather than lost protection — and it has its own page for Hill.
What makes one Hill petrol in a diesel task cost more than the next
Four separate jobs lie behind the four scenarios above — which is why there's no honest single quote. What shifts the cost is mostly which of them you are in. Two things follow that: the petrol that was put in as a share of what that tank holds, then the spot the vehicle is in and whether a technician can get to it safely.
Ahead of any quote, not after, we ask three queries: the fuel that went in, the volume, and if it has run. That's why. A range turns into a straight figure when those answers are in.
About Hill and its setting
Hill is a suburban area in West Yorkshire, situated on the riverside with a mix of terraced housing. Hill sits at an elevation of 219 metres, overlooking the surrounding landscape. Hill is located near other local places such as Under Hill, Holmfirth, and New Town, and is approximately 14 miles from Wakefield. Hill has a population of around 1873 residents.
Fuel drain cover across West Yorkshire, Hill included
Petrol in diesel jobs around Hill — part of the HD postcode area — go to vans that likewise cover the spots round it, Under Hill, Holmfirth and New Town among them. No need to bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places we drain.
At the pump around Hill, right now?
No position is better: that is where you now are. Call, and leave it turned off.