Overcombe: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — provided nobody has started the car. Petrol resting in a diesel tank does nothing to your engine until something pulls it through the fuel system — your ignition priming your pump, the starter, or the drive on its own. So the honest answer to the first query anyone in Overcombe asks, "have I ruined it?", is usually no. Leave the engine off then call Petrol in Diesel — that is how you keep it that way. What petrol really does to a diesel, how to judge how far it has gone, and how to keep it from happening a second time: that is the remainder of this page.
The engine and petrol in a diesel: what goes on
Two jobs fall to diesel on its route round a motor. It lubricates first, and only then does it burn. Built to extremely fine clearances, the injectors and your pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Badly at the first, not at all at the second: that's petrol. A pump working on a petrol mix is wearing itself out, because petrol is runnier than diesel and strips out the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any clattering comes.
Put those together and the shape of the trouble is plain. Contact does not do the damage — circulation does. Petrol in a tank is a fuel problem. After your pump has been running on that petrol, a mechanical issue has begun: whatever is shed by a pump that is wearing down is carried onward to the injectors with your fuel.
Overcombe, petrol in a diesel: four situations, from mild to significant
Filled up, and never started: nothing beats it. That petrol is inside that tank and only that tank, and the job is a drain and a flush where the car sits. This is the one situation that can only truly occur at a forecourt, since anywhere else the car has been driven to get there.
Started for a moment, or just your ignition on. Petrol has come out of that tank and reached the filter and your lines, because your system has been primed. Drain, flush, deal with the filter: still usually straightforward.
A couple of miles driven, and the pump has spent each of them working on diluted fuel. The work is the tank, the lines, your filter and fresh fuel through the whole system, and how hard your car was driven matters as much as how far. A school run to St Andrew's Church of England Primary School is one matter. Getting as far as Wells, under 50 miles away, makes a very different task — as does any distance on the M5, under 50 miles from Overcombe, with the motor working hard all the way.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven until it complained. That is the engine telling you its fuel has stopped behaving like diesel. Stop where you are — on the verge on Ringstead Crescent, at the kerb, down a side road — and do not move it. The drain and flush-through still come first, and they deal with it: when a vehicle is pulled over early, long-term damage is very uncommon.
Myths Overcombe drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — your tank simply carries more of the same blend. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. More precise parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches most drivers than any other. The motorist of a petrol motor fed diesel usually has no choice but to stop, because it will not run, and the damage stops with them. A diesel fed petrol generally starts, idles and drives away as though nothing has happened, whilst your pump grinds. Being able to run is not proof of being fine.
An outdated workaround for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive the car home." What petrol has diluted stays weakened, and that petrol remains inside the tank anyway.
The next start sends petrol back round your pump out of the fuel lines and your filter, where some of it ends up after the motor has been run. That is why draining the tank yourself doesn't sort it — a myth. Besides, petrol cleared into a can by the road is genuinely risky.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and no one means to do it. The petrol nozzle is the narrower of the two and slips 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.
The moment habit stops matching the car is the moment it happens. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. Your usual forecourt, its pumps suddenly in a different order. Rushing for a train at Weymouth and fuelling up en route. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it takes place. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up in Overcombe
- The label is what matters, and so read the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on every forecourt.
- In a motor you do not know, look inside the flap over the filler or at the cap before your first fill: many vehicles state the fuel type there.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, in a home with one of each.
- It sounds silly and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Tuck the phone away. This is an easy mistake to make whilst you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to reject a petrol nozzle, and aftermarket devices are available for the remainder. Treat it as a backstop, then keep checking the petrol pump.
- Less petrol makes a weaker mixture, and so stop as soon as you realise — while remembering that your next step is unchanged. It's still not to start the car.
Already put petrol in a diesel around Overcombe?
Then the order of things is brief. Leave it unstarted, with your ignition off too. If you're still on the forecourt — Sainsbury's or anywhere else — ask the attendants to help you roll it clear of the pump. Then ring 0333 366 0103 and tell us what went in, roughly how much, and if it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different problem — Overcombe has a page just for it.
Overcombe petrol in a diesel jobs: why one costs more than another
The four scenarios above are four separate jobs, so no single price for this would be fair. What shifts your cost is mostly which of them you are in. Where the vehicle is matters too, and whether a van can safely reach it, after the ratio of petrol to what the tank holds.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and that is the reason. Those answers are what change a range into one firm number.
About Overcombe, for a moment
Overcombe is a small suburban area situated on the coast of Dorset, with a mix of detached housing and scenic views. Overcombe sits at an elevation of 23 metres, close to nearby places such as Bowleaze, Preston, and Sutton Poyntz. Overcombe is located approximately 116.7 miles from London and 40.7 miles from the nearest city, Wells. Overcombe has a population of around 1503 residents.
Overcombe and Dorset: where our fuel drain cover reaches
Overcombe waits in the DT postcode area, and the teams that answer petrol in diesel call-outs there work the places around it as well — Bowleaze, Preston and Sutton Poyntz among them. Our technicians drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump around Overcombe, right now?
Nothing beats it: that is where you are. Ring, and leave it turned off.