Vale of Health: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, provided it has not been started. Everyone around Vale of Health starts with "have I ruined it?", and the fair answer is usually no: petrol left inside your tank of a diesel stays harmless until priming, cranking or driving draws it into the system. To leave it like that, call Petrol in Diesel then leave your engine alone. Keep reading for three things: the effect petrol has inside a diesel motor, the clues of how far it has spread, and the way to make sure you never do it again.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel does two jobs. Before it combusts, it protects — and then it combusts. What keeps the surfaces inside the high-pressure pump and your injectors from wearing down against one another is your diesel passing through them — they're designed to very fine tolerances.
Badly at the first, not at all at the second: that's petrol. The rattling comes from petrol being made not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the fuel system depends on, and any pump running on that mixture is wearing itself.
Put those together and the shape of the trouble is clear. Contact doesn't do the damage — circulation does. All a tank with petrol in it amounts to is a fuel fault. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors further on.
Petrol in a diesel in Vale of Health: how serious is it? Four situations
Filled up, and never started: nothing beats it. At a forecourt, and really only there, the petrol is still confined to that tank — because everywhere else the car was driven to reach it. The task is emptying and flushing on the spot.
Ignition on, or started for a moment. Once primed, the fuel system has pulled petrol out of that tank as far as the fuel filter and the lines. Usually nothing more than emptying, purging and sorting the fuel filter, and so still easy.
Your pump now worked a few miles on diluted fuel — that is what driving it meant. The work is the tank, the lines, the filter and fresh fuel through the entire circuit, and how hard the car was driven matters as much as how far. Driving the children to Christ Church Primary School, Hampstead is one sort of trip. Very different a second time: a trip to Westminster, under 5 miles away, or some distance on the M1, under 3 miles from Vale of Health, where the motor never stopped working hard.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The motor is telling you the fuel is no longer behaving like diesel. Whether it's the verge on East Heath Road, a lay-by or a side street, stop there then leave it. The fuel drain and flush still come first, and they take care of it: if a car is pulled over soon, lasting damage is very rare.
Vale of Health people and the petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Topping up removes nothing; it gives you a bigger tank of the same mix. The assumption behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer parts: that's how a newer diesel moves its fuel, so the lubrication matters for more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Any petrol engine fed diesel normally will not run, and so the motorist stops and the harm stops with them. Feed petrol to a diesel and it normally starts, idles and pulls away like nothing happened — all the while its pump is wearing. A running engine does not mean 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 diluted remains weakened, and that petrol remains in your tank regardless.
If your engine has been run, part of the petrol sits in the fuel filter and the fuel lines, not that tank — and your next start sends it straight back through the pump. So the myth "drain the tank yourself and you are sorted" does not stand up. Also, a can of petrol filled at the roadside is truly hazardous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol vehicle at all. So the error runs one way.
It takes place when routine and the car stop matching. A car that is new to you — a hire car, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. A rushed fill en route to Hampstead Heath with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it happens. Add rain, a phone call or a back seat full of kids, and the hand does what it has always done.
How to prevent petrol in a diesel on your next fill-up in Vale of Health
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what matters.
- Plenty of vehicles state the fuel inside your filler flap or on the cap, and so check there on your first fill in any motor you do not know.
- One of each in the house? Mark your key to your diesel — a bright fob, a sticker — because intending to remember isn't enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" aloud. Silly, yes, but it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Noticing it mid-fill? Stop there and then. A thinner blend follows from less petrol inside that tank, but the next stage stays the same: don't start it.
Vale of Health: already put petrol in a diesel?
Short and simple, then, is the order of things. Do not fire it up, and do not switch the ignition on. If you're still on the forecourt — BP or anywhere else — ask the attendants to help you push the vehicle clear of the pump. Call 0333 366 0103 next, with three answers — your fuel, the approximate quantity, and if it's run.
If it was AdBlue rather than petrol, say so. That is a separate problem — corrosion and deposits instead of lost protection — and it has its own page for Vale of Health.
One petrol in a diesel job around Vale of Health costs more than another. Why?
Four different tasks lie behind the four situations above — which is why there's no honest single price. What moves your cost is mostly which of them you are in. Where your car is counts too, and whether a van can safely get to it, after the proportion of petrol to what your tank takes.
Ahead of any quote, not after, come three queries: the fuel that got in, its amount, and whether it has run. That is why. Given those answers, there is a straight figure rather than a range.
About Vale of Health, for a moment
Vale of Health is a suburban area in north London, situated near Hampstead and Frognal, with a mix of residential flats and local amenities. Vale of Health sits at an elevation of around 136 metres, overlooking the surrounding urban landscape. Vale of Health is close to central London, being approximately 4.3 miles from the city centre and 4.7 miles from Westminster. Vale of Health has a population of around 5992 people, predominantly residing in flats.
Vale of Health and Greater London: where our fuel drain cover runs
Our vans answering petrol in diesel jobs around Vale of Health, in the NW postcode area, also work the locations near it, Hampstead, Frognal and North End among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we drain, and the vehicle does not need to come to us.
Vale of Health: still at the pump?
The best place there is, then — that is where you are. Ring, and leave it turned off.