Should You Worry? Petrol in a Diesel Car in The Chart
Less than you probably are, provided it hasn't been started. "Have I wrecked it?" is the first thing everyone in The Chart asks, and the truthful answer is usually no, since petrol left in a diesel tank hurts nothing until it's dragged through the system — by ignition priming, by the starter, or by being driven. Petrol in Diesel is who to phone, with your engine kept off, so it remains that way. What petrol actually does to a diesel, how to judge how far it's gone, and how to keep it from happening a second time: that's the rest of this page.
Inside your engine: what petrol in a diesel really does
Passing through an engine, diesel does two jobs at the same time. It lubricates to begin with, and after that does it burn. The high-pressure pump and the injectors are built to extremely fine tolerances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Petrol does 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 that mixture to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the knocking.
Seen together, they show the shape the trouble has. The damage is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
Petrol in a diesel around The Chart: how serious is it? Four situations
Fuelled up, never started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol held in the tank alone, it is emptied and rinsed right where it stands, and nothing more is needed.
A moment's running, or merely the ignition on. Once primed, the system has pulled petrol out of the tank as far as the filter and the fuel lines. Normally little more than emptying, rinsing and seeing to the filter, and so still easy.
Driven a couple of miles. Now your pump has spent those miles running on weakened fuel. Distance is only half of that; how hard it was driven counts equally. Either way this work runs to the tank, the lines, the fuel filter and clean fuel through the whole system. A school run to Limpsfield CofE Infant School is one thing. A run as far as Westminster, under 25 miles away, is a very different task. So is any miles on the M25, under 3 miles from The Chart, where the motor has been labouring hard throughout.
Driven till it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. The fuel is not acting like diesel any more, and your motor is telling you. Pull up where you are — on the verge on Mill Lane, at the kerb, down a side road — and don't move it again. Lasting damage is very uncommon if a car is stopped soon, and the fuel drain and flush-through that still go first sort it out.
Petrol in a diesel stories The Chart motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Topping up removes nothing; it gives you a bigger tank of the same mixture. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: a current diesel copes with a bit of petrol. Rather, the reverse. A newer diesel sends its fuel through more precise components at higher pressure, which makes the protection count more, not less.
"It starts, it drives, so there is no harm" — the myth that catches most motorists than any other. The driver of a petrol motor fed diesel usually has no choice but to stop, because it will not run, and the harm stops there. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, whilst your 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 issue. What petrol has thinned remains diluted, and the petrol remains inside that tank anyway.
Myth: "Drain that tank yourself and you are sorted." Once the motor has been run, some of the petrol is no longer in your tank: it's in the filter and the lines, and it goes straight back through the pump at your next start. Also, a can of petrol drained at the kerbside is genuinely hazardous.
Why petrol in a diesel occurs at all
A careless moment is seldom the cause, and no one means to do it. A diesel nozzle mostly won't go into a petrol motor, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and just in that direction.
When habit and the vehicle stop matching, it occurs. Any vehicle that is new to you — hired, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Racing for a train at Hurst Green and fuelling up en route. Exactly the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Tiguan for the first time. Your hand does what it has always done when you add rain, a phone call or a back seat full of kids.
Next time you fill up in The Chart: preventing petrol in a diesel
- The label is what matters, and so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- Many motors state the fuel inside the filler flap or on the cap, and so check there on your first fill in any vehicle you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a home with one of each.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- Mistakes like this are simple to make while your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop reading the pump.
- The moment you notice, stop: less petrol inside that tank means a weaker mix. What to do next doesn't change, though — still do not crank it.
The Chart: already put petrol in a diesel?
In that case, there's just a short order of things. Leave it unstarted, with your ignition switched off as well. The attendants on the forecourt — whether at BP itself or wherever you filled up — will usually help push it away from the pump if you ask. Ring 0333 366 0103 next, with three answers — the fuel, the rough quantity, and if it's run.
If it was AdBlue instead of petrol, say so. That is a different fault — corrosion and deposits rather than lost lubrication — and it has its own page for The Chart.
Why one petrol in a diesel job around The Chart costs more than another
The four scenarios above are four separate tasks, so no single price for this would be honest. Chiefly, your cost moves with which one you're in. Where the vehicle is counts too, and whether our van can safely reach it, after the proportion of petrol to what the tank holds.
Three questions come first, before quoting, rather than after — what was put in, how much, has it run — and that is the reason. A range turns into a straight figure once the replies are in.
About The Chart and where it is
The Chart is a small village in Surrey, situated inland at an elevation of around 175 metres. The Chart lies within the South East region of England, approximately 19 miles from London, and is characterized by semi-detached housing. The Chart is near other local places such as Limpsfield Chart and Limpsfield Common, and has a population of around 520 residents.
Fuel drain cover across Surrey, The Chart included
The Chart sits in the RH postcode area, and our vans that answer petrol in diesel calls there work the spots near it as well — Limpsfield Chart, Limpsfield Common and Goodley Stock among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations we work, and the vehicle does not need to come to us.
The Chart: still at the petrol pump?
Nothing beats it: that's where you now are. Keep it off. Call.