How Worried Should You Be? Petrol in a Diesel Car in Hurst
Probably less than you are now — provided no one has started it. "Have I ruined it?" is the first question anyone in Hurst asks, and the honest answer is normally no, because petrol resting in a diesel tank harms nothing till it is dragged through your fuel system — by ignition priming, by your starter, or by driving. Petrol in Diesel is who to call, with the engine kept off, so it stays that way. Further down, this page sets out what petrol actually does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
The motor and petrol in a diesel: what happens
Two tasks fall to diesel on its route round a motor. Lubricating comes before burning; it does both. What stops the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing down against each other is your diesel passing through them — they're built to very fine clearances.
Of these two tasks, petrol handles the first poorly and the second never. It is runnier than diesel and strips away the lubrication the system hinges on, so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the rattling comes from.
The shape of the trouble is plain when you put those together. The damage is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
How serious is petrol in a diesel? Four situations our technicians see around Hurst
Filled up, not once started. The best case there can be. Just that tank has petrol in it, and so the job is emptying that tank and cleaning your system where the vehicle sits. This situation can only truly take place on a forecourt: anywhere else, the vehicle got there by being driven.
Ignition on, or started for a moment. The fuel system has been primed, so petrol has left that tank and got to the fuel filter and the lines. That's generally still an easy job — a drain, a flush, and your filter seen to.
Driven a few miles. Now the pump has spent those miles labouring on weakened fuel. Tank, lines, filter, then clean fuel run through the whole circuit: that is the work, and the way the vehicle was driven counts as much as the mileage. The school run to St Nicholas Church of England Primary, Hurst is one thing. Any miles on the M4, under 3 miles from Hurst, means the motor has worked hard throughout, and a run to Oxford, under 50 miles away, makes a very different task too.
Driven on until it complained — clattering, smoke, a ragged idle, a dead throttle. What you are hearing is the motor signalling fuel that no longer acts like diesel. Stop on the spot — on the verge on Hurst Road, at the kerb, down a side road — and don't move it again. A vehicle pulled over soon very seldom has lasting damage, because the fuel drain and the flush-through, which still come first, take care of it.
What Hurst people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mixture is all you get, since topping up takes out nothing. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice presumes.
If anything, the reverse is true. Myth: "A current diesel can cope with a bit of petrol." Lubrication counts more on current diesels, not less, since their fuel runs through smaller components at higher pressure.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally leaves a motor that won't run: the motorist stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive it home." It is an outdated workaround for a separate issue. It doesn't put back what petrol has weakened, and that petrol is still inside your tank later on.
Myth: "Drain the tank yourself and you're sorted." Once the engine has run, some of that petrol is no longer in the tank: it's in your filter and the lines, and it goes right back through your pump at the next start. Besides, petrol drained into a can by the road is truly hazardous.
Petrol in a diesel: how does it take place?
It's rarely carelessness, and nobody does it on purpose. A diesel nozzle generally will not go into a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake easy, and only in one direction.
Routine and your car falling out of step is when it happens. Courtesy car, hire car, or a vehicle that is brand new. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Rushing for a train at Twyford and filling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a driver used to petrol: exactly when it happens. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
Hurst motorists: 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. Check the petrol pump's label; the colour is only a hint.
- In a car you don't know, look inside the flap over your filler or at the cap before the first fill: many motors state the fuel type there.
- Label the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" aloud. Daft, perhaps, yet it does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, and so the phone goes 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 vehicles without one. They are a safety net, not a reason to stop checking the pump.
- Stop as soon as you realise. Less petrol in your tank makes a thinner mix. It doesn't change what to do next, which is still not to start it.
Hurst: already put petrol in a diesel?
The order of things is short, then. Starting it is out, and so is switching on your ignition. The attendants on the forecourt — whether at Texaco itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Phone 0333 366 0103 next, with three facts — the fuel, the rough quantity, and whether it has run.
If it was AdBlue instead of petrol, say so. That's a separate issue — corrosion and deposits and not lost lubrication — and it has its own page for Hurst.
What makes one Hurst petrol in a diesel task cost more than the next
Four separate tasks lie behind the four scenarios above — which is why there is no fair single price. Chiefly, the cost moves with which situation you're in. Two things come after that: the petrol that was put in as a share of what that tank takes, then the spot the vehicle is in and whether a van can get to it safely.
Three questions come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. With those answers, you get a straight figure rather than a range.
About Hurst, for a moment
Hurst is a small village in Berkshire, situated inland at an elevation of approximately 40 metres. Hurst lies near the villages of Whistley Green and Woodley Green, and is close to the town of Twyford. Hurst is characterized by its predominantly detached housing stock and is home to around 1014 residents. Hurst is also within commuting distance of major cities, including Oxford and London.
Fuel drain cover in Hurst and across Berkshire
Hurst rests in the RG postcode area, and the teams that answer petrol in diesel jobs there work the locations near it as well — Whistley Green, Woodley Green and Twyford among them. The car does not need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump in Hurst?
Then you are in the best place there can be. Keep it off. Ring.