Jump: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, you can worry far less than you likely are. Petrol resting in a diesel tank does nothing to the engine till something pulls it through the system — the ignition priming your pump, the starter, or driving itself. So the honest answer to the first question anyone around Jump asks, "have I wrecked it?", is usually no. Keep it that way: leave the motor off and call Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it has travelled, 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 your engine?
On its way through a motor, diesel does two tasks. It protects to begin with, and only then does it burn. What keeps the surfaces inside the high-pressure pump and the fuel injectors from wearing against each other is the diesel passing through them — they are made to extremely fine gaps.
The second job petrol does not do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump running on the mixture to wear itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Seen together, they make clear what shape the issue has. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel issue. Once the pump has been running on that petrol, a mechanical fault has begun: anything shed by a pump that's wearing down is carried downstream to the injectors with your fuel.
Jump, petrol in a diesel: four situations, from mild to major
The best case there is: filled up, not once started. Being at a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol kept in your tank alone, it is emptied and purged on the spot, and nothing more is needed.
A brief spell of running, or merely the ignition on. With the fuel system primed, the lines and filter already hold petrol that has come from the tank. Still usually easy: drain, flush, and the fuel filter seen to.
The pump now spent a couple of miles on diluted fuel — that is what driving the car does. Distance is only half of that; how hard it was driven matters just as much. Either way this work runs to your tank, your lines, the fuel filter and clean fuel through the whole circuit. Short trips, like the school run to Jump Primary Academy, are one matter. A run as far as Sheffield, under 10 miles away, is a very different job. So is any mileage on the M1, under 3 miles from Jump, where your engine has been labouring hard throughout.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. That's the engine telling you its fuel no longer is acting like diesel. Stop wherever you are — the verge on Wentworth Road, a lay-by, a side street — and leave it there. The drain and flush-through still go first, and they deal with it: if a car is stopped soon, lasting damage is very rare.
What Jump drivers get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that's how a modern diesel handles its fuel, so the lubrication matters more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches people. Feed diesel to a petrol engine and it usually will not run, and so the driver stops — and the harm stops with them. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, whilst your pump grinds. Fine and running aren't the same thing.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an old workaround for a distinct issue. The petrol is still in the tank afterwards, and whatever it has diluted isn't put back.
If your engine has run, part of that petrol sits in your filter and the lines, not your tank — and your next start pulls it straight back through your pump. So the myth "drain your tank yourself and you're sorted" does not stand up. It is also genuinely risky to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle generally will not fit a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and only in one direction.
It occurs when routine and your car stop matching. A motor that's new to you — a hire car, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps laid out differently. Racing for a train at Elsecar and fuelling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: precisely when it takes place. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Jump drivers: 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. Read the petrol pump's label; the colour is just a clue.
- Inspect your filler flap. Plenty of motors state the fuel inside the flap or on the cap. Look at it on your first fill in any motor you don't know.
- Mark your key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems daft and it works.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone 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 cars without one. They are a safety net, not a reason to stop reading the petrol pump.
- The moment you notice, stop: less petrol in the tank means a weaker blend. What to do next doesn't change, though — still do not fire it up.
Put petrol in a diesel around Jump already?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. The attendants on the forecourt — whether at Brobot Hoyland Service Station itself or wherever you filled up — will usually help push it away from the pump if you ask. Then phone 0333 366 0103 and tell us what got in, about how much, and whether it has run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Jump, since AdBlue brings corrosion and deposits rather than lost lubrication.
Jump petrol in a diesel tasks: why one costs more than another
There is no honest single quote for this, since the four situations above are four separate tasks. Which of them you are in is mostly what shifts the cost. Two things follow that: the petrol that got in as a share of what the tank holds, then the spot your car is in and whether our van can reach it safely.
What went in, how much, and whether it has run — three questions we ask before costing, not after, for precisely that reason. Those answers change a range into a straight figure.
About Jump itself
Jump is a small village in South Yorkshire, situated inland at an elevation of 106 metres, approximately 8.8 miles from Sheffield. Jump is characterized by its semi-detached housing and is located near Platts Common, Hoyland, and Hemingfield. Jump has a population of around 1424 residents and is within commuting distance of major cities, being 148.6 miles from London.
Jump and South Yorkshire: where our fuel drain cover reaches
Jump sits in the S postcode area, and the vans that answer petrol in diesel jobs there work the places around it as well — Platts Common, Hoyland and Hemingfield among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we work, and your car doesn't need to move to us.
Still at the petrol pump around Jump?
Then you're in the best place there can be. Switched off it stays; then call.