Should You Worry? Petrol in a Diesel Car in Sandhills
Unstarted? Then less anxious than you probably are. "Have I ruined it?" is the first question anyone in Sandhills asks, and the truthful answer is generally no, since petrol left in a diesel tank hurts nothing until it is dragged through the fuel system — by ignition priming, by the starter, or by being driven. Keep it that way: leave the motor off then call Petrol in Diesel. The rest of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
What petrol in a diesel does to the engine
Two tasks fall to diesel on its journey round a motor. It burns, and before it ignites it lubricates. What stops the surfaces inside the high-pressure pump and your injectors from wearing against each other is the diesel passing through them — they are built to extremely fine tolerances.
Badly at the first, not at all at the second: that is petrol. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the lubrication the fuel system hinges on, and any pump working on that mix is wearing itself.
Together, those leave the shape of the problem plain. The damage is done by movement, not by contact. Where the petrol is only inside that tank, it is a problem of fuel, nothing more. Whatever a worn pump sheds travels on, carried by the fuel, into your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical issue begins.
Four situations our technicians see in Sandhills: how serious is petrol in a diesel?
Fuelled, and not started: no case is better. At a forecourt, and really only there, the petrol is still limited to your tank — since everywhere else the car was driven to reach it. The job is emptying and rinsing on the spot.
A brief spell of running, or just your ignition on. The fuel system has been primed, and so petrol has left that tank and got to the fuel filter and the lines. Still usually easy: drain, flush, and your filter seen to.
Those few miles on the road were the pump working on fuel diluted by petrol throughout. Miles is only half of that; how hard it was driven matters just as much. Either way the work includes your tank, your lines, your filter and clean fuel through the whole circuit. The school run to Kirkdale St Lawrence CofE VA Primary School is one thing. Any mileage on the Kingsway, under 5 miles from Sandhills, means your engine has worked hard throughout, and a run to Liverpool, under 3 miles away, makes a very different job too.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. The engine is telling you the fuel is no longer behaving like diesel. Stop wherever you are — the verge on St Johns Road, a lay-by, a side street — then leave the vehicle there. A vehicle stopped quickly very rarely has long-term damage, because the drain and the flush-through, which still go first, sort it out.
Stories Sandhills motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." Smaller components and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel usually has no choice but to stop, since it will not run, and the damage stops there. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, while your pump wears. A running engine does not mean fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old workaround for a different problem. None of what petrol thinned is put back by it — and later, that tank still holds that petrol.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol lies in your filter and lines, ready to go right back through your pump at the next start. On top of that, petrol cleared into a can by the road is truly hazardous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol vehicle at all. The forecourt makes it easy, and the mistake runs one way.
It happens when habit and the car stop matching. Courtesy car, hire car, or a vehicle that's brand new. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. Racing for a train outside Bank Hall and filling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. The hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
How to prevent petrol in a diesel on your next fill-up in Sandhills
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what matters.
- Inspect your filler flap. Plenty of vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in a car you don't know.
- One of each in the household? Mark your key to the diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- "Diesel", aloud, before you lift the nozzle — every time a new or hired car gets its first tank. It seems daft. It works.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop reading the pump.
- Stop the moment you realise. Less petrol in your tank means a thinner mixture. It does not change what to do next, which is still not to crank it.
Already put petrol in a diesel in Sandhills?
Then, there's just a short order of things. Leave it unstarted, with your ignition off too. If you're still on the forecourt — Shell or anywhere else — ask the staff to help you roll the vehicle away from the petrol pump. What got in, roughly how much, and whether it's run: tell us that when you ring 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a separate problem, with its own page for Sandhills, since AdBlue brings corrosion and deposits rather than lost lubrication.
Why one petrol in a diesel task around Sandhills costs more than another
There is no honest single price for this, since the four situations above are four separate jobs. The situation itself does most of the work of moving your cost. Two things follow that: the petrol that was put in as a share of what your tank holds, then the place the car is in and whether a van can reach it safely.
Before any quote, not after, come three queries: your fuel that went in, its quantity, and whether it's run. That's why. A range turns into a straight figure when those replies are in.
About Sandhills
Sandhills is a coastal suburban area in Merseyside, situated near the city of Liverpool, with Sandhills being one of the closest suburbs to the city centre. Sandhills sits at an elevation of 21 metres, with Sandhills' proximity to the coast influencing its development as a residential area. Sandhills is characterised by its predominance of terraced housing, with Sandhills being home to a population of approximately 4768 people.
Fuel drain cover in Sandhills and across Merseyside
Sandhills waits in the L postcode area, and our teams that answer petrol in diesel jobs there work the spots around it as well — Kirkdale, Walton and Bootle among them. Our technicians drain where the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the petrol pump in Sandhills, right now?
No position is better: that's where you now are. Leave the vehicle switched off, then ring.