Chiseldon: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, provided it has not been started. "Have I wrecked it?" is the first question anyone around Chiseldon asks, and the honest answer is generally no, since petrol left in a diesel tank harms nothing until it is dragged through your fuel system — by ignition priming, by the starter, or by being driven. Keep it that way: leave the motor off then ring Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it's gone, and how to stop it from happening a second time: that is the rest of this page.
Petrol in a diesel: what does it do to the motor?
Passing through an engine, diesel is doing two jobs at once. Oiling comes before burning; it does both. The high-pressure fuel pump and your injectors are made to extremely fine clearances, and the diesel passing through them is what keeps those surfaces from wearing against each other.
The second job petrol does not do at all, and the first it does badly. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication your system depends on, and any pump working on such a mix is wearing itself.
Combined, those leave the shape of the issue clear. Contact doesn't do the harm — movement does. Petrol in the tank is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors downstream, which is why a pump that has been working on that petrol is where a mechanical problem starts.
Petrol in a diesel around Chiseldon: how bad is it? Four cases
Filled up, never started. The best case there can be. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept inside the tank alone, it is cleared and cleaned right where it stands, and nothing more is needed.
A brief spell of running, or merely your ignition on. Once primed, the system has pulled petrol from that tank up to the filter and your lines. Drain, flush, see to the fuel filter: still normally easy.
The pump has spent a couple of miles on thinned fuel — that's what driving it does. The work is that tank, your lines, the filter and fresh fuel through the whole system, and how hard your car was driven matters as much as how far. The school run to Chiseldon Primary & Nursery School is one thing. A run as far as Oxford, under 50 miles away, is a very different job. So is any miles on the M4, under a mile from Chiseldon, where the engine has been labouring hard the whole time.
Driven on until it protested — clattering, smoke, a ragged idle, a dead throttle. The fuel is not acting like diesel any more, and your motor is saying so. Pull up on the spot — on the verge on Turnball, at the kerb, down a side road — and don't move it. The drain and flush-through still go first, and they deal with it: if a vehicle is pulled over quickly, permanent damage is very rare.
Chiseldon people and that petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — your tank just carries more of the same blend. The assumption behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. Smaller parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication count more, not less.
One 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 driver stops — and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old fix for a separate issue. None of what petrol thinned gets put back by it — and afterwards, the tank still contains that petrol.
Once your engine has been run, part of that petrol sits in the fuel filter and the fuel lines, not the tank — and your next start sends it right back through the pump. So the myth "drain the tank yourself and you're sorted" doesn't hold. Also, a can of petrol drained at the roadside is genuinely hazardous.
How does petrol in a diesel occur?
It is rarely carelessness, and no one does it on purpose. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol vehicle at all. So the error runs one way.
The moment habit stops matching your car is the moment it occurs. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps now in a different order. Rushing for a train at Swindon and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. With rain, a call coming in, or children to deal with, the hand just does what it has always done.
Avoiding petrol in a diesel next time you fill up in Chiseldon
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in a new vehicle is the time to check your filler flap — on it, or on the cap, plenty of cars state the fuel they take.
- Mark your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It seems daft and it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices exist for the rest. Treat it as a backstop, then keep checking the pump.
- The moment you notice, stop: less petrol in your tank means a weaker blend. What to do next doesn't change, though — still don't fire it up.
Petrol already in a diesel around Chiseldon? Start here
The order of things is brief, then. Starting it is out, and so is turning on your ignition. If you are still on the forecourt — Esso or anywhere else — ask the staff to help you push the vehicle clear of the pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it's a separate fault, with its own page for Chiseldon, since AdBlue brings corrosion and deposits instead of lost lubrication.
What makes one Chiseldon petrol in a diesel job cost more than the next
There is no fair single price for this, because the four situations above are four different tasks. What shifts your cost is chiefly which of them you're in. Next it's the ratio — how much petrol was put in against how much the tank holds — and then where the car is and whether a technician can get to it safely.
Before any quote, not after, we ask three questions: the fuel that was put in, its quantity, and whether it's run. That's why. Those answers turn a range into a straight figure.
About Chiseldon, briefly
Chiseldon is a village in Wiltshire, situated inland at an elevation of 161 metres, approximately 26 miles from Oxford and 69 miles from London. Chiseldon is characterised by its semi-detached housing and is located near other small villages such as Badbury, Hodson, and Medbourne. Chiseldon has a population of around 1753 residents, making it a small but established community in the South West region.
Fuel drain cover across Wiltshire, Chiseldon included
The teams answering petrol in diesel jobs in Chiseldon, in the SN postcode area, equally work the locations around it, Badbury, Hodson and Medbourne included. The vehicle does not need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the pump around Chiseldon?
In that case, you couldn't be in a better position. Turned off it remains; then ring.