Ford: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, provided it hasn't been started. Till the ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank simply rests there and does no harm. Which means the truthful reply to that first Ford question — "have I wrecked it?" — normally no. Keep it like that: leave your engine off and phone Petrol in Diesel. What petrol really does to a diesel, how to judge how far it's gone, and how to keep it from happening again: that is the rest of this page.
What petrol in a diesel does to the engine
Diesel does two tasks on its way through a motor. It combusts, and before it burns it lubricates. Designed to extremely fine gaps, your injectors and the pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Of these two tasks, petrol handles the first poorly and the second not at all. It's runnier than diesel and removes the lubrication the fuel system depends on, and 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 is where the knocking comes from.
Combined, those leave the shape of the trouble plain. It is movement that causes the harm, not contact. Where that petrol is only inside the tank, it is a problem of fuel, nothing more. Once the pump has been labouring on that petrol, a mechanical fault has begun: whatever is shed by a pump that is grinding is carried onward to your injectors with your fuel.
Ford, petrol in a diesel: four cases, from mild to serious
The best case there can be: filled up, never started. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept inside that tank alone, it's cleared and purged right where it stands, and nothing more is needed.
A moment's running, or merely the ignition on. Petrol has come out of that tank and reached the fuel filter and your lines, since the system has been bled. Usually nothing more than draining, cleaning and sorting the filter, so still straightforward.
Those few miles driven meant the pump labouring on fuel diluted by petrol throughout. How hard your car was driven counts as much as how far, and this work takes in your tank, the lines, the fuel filter and fresh fuel through the entire circuit. Driving the kids to Trinity CofE Primary School is one kind of trip. A run as far as Wrexham, under 25 miles away, is a very different job. So is any mileage on the M54, under 15 miles from Ford, where the motor has been running hard throughout.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. The motor is telling you the fuel is no longer behaving like diesel. Stop on the spot — on the verge on The Leasowes, at the kerb, down a side road — and do not move it. Long-term damage is very unusual when a car is pulled over quickly, and the drain and flush that still go first sort it out.
Petrol in a diesel myths Ford people hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through smaller parts: that is how a newer diesel handles its fuel, and so the protection matters for more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that fools motorists. Diesel in a petrol motor usually means a motor that won't run: the driver stops, and so does the harm. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump wears. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct issue. What petrol has thinned stays thinned, and the petrol remains in your tank anyway.
The next start draws petrol back round the pump out of the lines and your filter, where some of it ends up once your engine has run. That's why draining your tank yourself does not sort it — a myth. Emptying petrol into a can at the roadside is also truly risky.
Petrol in a diesel: how does it occur?
It is rarely carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol vehicle at all. So the slip runs one way.
When habit and your car stop matching, it takes place. Courtesy car, hire car, or a car that is new. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. Filling up in a hurry on the way to Shrewsbury, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: precisely when it occurs. Add a back seat full of kids, a phone call or rain, and the hand takes over.
How to prevent petrol in a diesel at your next fill-up around Ford
- The label is what matters, so check the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on every forecourt.
- The first fill in a new motor is the time to check your filler flap — inside it, or on the cap, many motors state which fuel to use.
- Label your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It seems daft. It does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, and so your phone goes away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol inside that tank makes a weaker blend. What to do next doesn't change, though — still do not fire it up.
Ford: already put petrol in a diesel?
Then the order of things is short. Starting it is out, and so is switching on the ignition. The attendants on the forecourt — whether at Shell itself or wherever you filled up — will usually help push it clear of the petrol pump if you ask. Call 0333 366 0103 next, with three answers — the fuel, the rough amount, and if it has run.
Corrosion and deposits form the issue with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and see its own Ford page.
Ford petrol in a diesel tasks: why one costs more than another
The four scenarios above are four different tasks, so no single price for this would be fair. Which of them you are in is chiefly what shifts your cost. Two things come after that: the petrol that was put in as a proportion of what your tank holds, then the place the car is in and whether a technician can reach it safely.
That is why we ask three questions before costing instead of after: what went in, how much, and whether it's run. With the answers, you get a straight figure instead of a range.
About Ford, briefly
Ford is a village in Shropshire, situated on the riverside at an elevation of 73 metres, with semi-detached housing being the predominant type of accommodation. Ford lies near several smaller settlements, including Butlane Head, Chavel, and Shoot Hill, and is approximately 23 miles from Wrexham. Ford is a relatively small community, with a population of around 693 people, and is located in the West Midlands region of England. Ford is also some distance from major urban centres, being around 143 miles from London.
Across Shropshire and in Ford: fuel drain cover
Ford waits in the SY postcode area, and the vans that answer petrol in diesel call-outs there work the locations near it as well — Butlane Head, Chavel and Shoot Hill among them. Our engineers drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the petrol pump in Ford, still?
In that case, you couldn't be in a better spot. Keep the car switched off, then ring.