Wiveliscombe: Petrol in a Diesel Car? How Worried to Be
If it has not been started, worry less than you likely are. Everyone in Wiveliscombe begins with "have I ruined it?", and the fair answer is generally no: petrol left inside that tank of a diesel stays harmless till priming, cranking or driving draws it into your fuel system. Petrol in Diesel is who to phone, with your motor left off, and so it stays that way. The rest of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Inside your engine: what petrol in a diesel really does
Two jobs fall to diesel on its route round a motor. It burns, and before it burns it lubricates. Very fine tolerances go into the fuel injectors and the high-pressure fuel pump, and only your diesel flowing through stops their surfaces grinding together.
Petrol does the first task badly and the second not at all. The rattling 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 thinner than diesel, it strips out the protection the fuel system depends on, and any pump running on that blend is wearing itself.
The shape of the issue is clear when you put those together. Contact doesn't do the harm — circulation does. Any tank with petrol in it is a fuel fault. Once your pump has been running on that petrol, a mechanical fault has begun: anything shed by a pump that is grinding travels onward to the fuel injectors with your fuel.
How serious is petrol in a diesel? Four scenarios our technicians see in Wiveliscombe
Fuelled but never started — as good as it gets. At a forecourt, and genuinely only there, that petrol is still confined to the tank — because anywhere else your car was driven to reach it. The task is emptying and purging on the spot.
The ignition switched on, or a brief start. With the system primed, the fuel lines and filter now hold petrol that has come from the tank. Normally little more than draining, cleaning and seeing to your filter, and so still straightforward.
Those few miles driven meant your pump running on fuel thinned by petrol throughout. The work is your tank, your lines, the filter and clean fuel through the whole system, and how hard the vehicle was driven counts as much as how far. On the school run to Wiveliscombe Primary School, the miles is short. Any miles on the M5, under 10 miles from Wiveliscombe, means the engine has worked hard throughout, and a run to Exeter, under 25 miles away, is a very different job as well.
Knocking, a ragged idle, smoke, a throttle gone soft: driven till it complained. The fuel isn't behaving like diesel any more, and your engine is telling you. Whether it's the verge on The Square, a lay-by or a side road, stop there and leave it. What comes first is still the drain and flush-through, and that deals with it, with long-term damage very unusual when a car is pulled over soon.
Petrol in a diesel myths Wiveliscombe motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed when you top up — your tank simply carries more of the same mixture. That advice assumes a diesel fuel system handles petrol by percentage. It doesn't.
If anything, the opposite holds. Myth: "A modern diesel can cope with a bit of petrol." Protection counts more on newer diesels, not less, because their fuel runs through smaller components at higher pressure.
This is the one that catches motorists. Myth: "If it starts and drives, there's no harm done." 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 usually starts, idles and drives away as though nothing has happened, while your pump grinds. A running engine does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct problem. None of what petrol diluted gets put back by it — and afterwards, the tank still holds the petrol.
Myth: "Drain your tank yourself and you're sorted." After the engine has been run, some of the petrol is no longer in that tank: it is in the filter and the fuel lines, and it goes right back through the pump on the next start. Draining petrol into a can by the kerbside is also really risky.
How petrol ends up: petrol in a diesel
It's rarely carelessness, and no one does it on purpose. A diesel nozzle generally won't go into a petrol motor, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error simple, and only in that direction.
Routine and your car falling out of step is when it occurs. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. A well-known forecourt with the pumps in a different order. Filling up in a hurry on the way to Tiverton Parkway, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it happens. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Wiveliscombe motorists: how to prevent petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is just a clue.
- Plenty of motors state the fuel inside the filler flap or on the cap, so check it on the first fill in any motor you do not know.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key if a household has one of each. So mark it.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It sounds daft. It works.
- Mistakes like this are straightforward to make while your mind is on something else, so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to block a petrol nozzle, and aftermarket devices are available for the remainder. Treat it as a safety net, then keep checking the petrol pump.
- As soon as you notice, stop: less petrol in that tank makes a thinner blend. What to do next doesn't change, though — still do not crank it.
Petrol already in a diesel in Wiveliscombe? Begin here
The order of things is brief, then. Don't turn your ignition on, and don't start it. Ask the staff to help you push it away from the petrol pump if you are still on the forecourt, whether that is the nearest petrol station or somewhere else. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate issue — Wiveliscombe has a page just for it.
Wiveliscombe petrol in a diesel tasks: why one costs more than another
Four separate jobs lie behind the four scenarios above — which is why there is no fair single quote. What shifts your cost is chiefly which of them you're in. Where the car is matters too, and whether a technician can safely get to it, after the share of petrol to what the tank takes.
Before any quote, not after, we ask three questions: the fuel that got in, its amount, and if it has run. That is why. A range turns into a straight figure once those answers are in.
About Wiveliscombe itself
Wiveliscombe is a small town in inland Somerset, situated at an elevation of 128 metres, with a population of around 2715 people. Wiveliscombe lies near the villages of Hartswell, Langley, and Ford, and is approximately 24 miles from Exeter. Wiveliscombe has a mix of housing types, but detached homes are particularly prevalent. Wiveliscombe is also relatively distant from London, at around 141 miles away.
Fuel drain cover across Somerset, Wiveliscombe included
Wiveliscombe sits in the TA postcode area, and the vans that answer petrol in diesel jobs there work the locations around it as well — Hartswell, Langley and Ford among them. Our technicians drain where the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Wiveliscombe and still at the petrol pump?
Nothing beats it: that is where you now are. Phone, and leave it switched off.