Dullatur: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you likely are. Everyone in Dullatur begins with "have I wrecked it?", and the fair answer is normally no: petrol left in the tank of any diesel stays harmless till priming, cranking or driving draws it into your fuel system. Keep it that way: leave your motor off then ring Petrol in Diesel. The remainder of this page explains what petrol actually does to a diesel, how to tell 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
On its way through an engine, diesel does two jobs. Lubricating comes before burning; it does both. Very fine tolerances go into the fuel injectors and the high-pressure pump, and only the diesel flowing through keeps their surfaces from grinding together.
Of those two jobs, petrol handles the first badly and the second not at all. The knocking comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection your system depends on, and any pump working on such a blend is wearing itself.
Combined, those make the shape of the problem plain. Not contact but circulation is what does the damage. Any tank with petrol in it is a fuel fault. Whatever a worn pump sheds goes on, borne by the fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical problem starts.
Four situations our engineers see in Dullatur: how serious is petrol in a diesel?
The best case there is: filled up, never started. At a forecourt, and really only there, the petrol is still confined to that tank — since everywhere else the vehicle was driven to get to it. The job is emptying and purging on the spot.
A brief spell of running, or just your ignition on. With your system primed, your lines and filter already hold petrol that came from the tank. Drain, flush, see to the fuel filter: still normally easy.
Driven a couple of miles. Now the pump has spent those miles labouring on diluted fuel. The work is your tank, your lines, your filter and fresh fuel through the entire circuit, and how hard your car was driven counts as much as how far. Driving the kids to the local primary school is one kind of trip. A run as far as Stirling, under 15 miles away, is a very different task. So is any distance on the M80, under 3 miles from Dullatur, where the engine has been working hard throughout.
Driven till it protested. Rattling, a ragged idle, smoke, a throttle that has gone soft. What you are hearing is the engine reporting fuel that no longer behaves like diesel. Stop wherever you are — the verge on Glen Road, a lay-by, a side street — and leave the vehicle there. A vehicle stopped early very rarely has permanent damage, since the fuel drain and the flush-through, which still go first, deal with it.
Dullatur people and the petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — that tank simply carries more of the same mixture. That advice supposes 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 opposite. A modern diesel sends its fuel through smaller components at higher pressure, which makes the lubrication matter more, not less.
The myth that catches drivers out: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel normally has no choice but to stop, because it will not run, and the damage stops there. Feed petrol to a diesel and it generally starts, idles and pulls away as if nothing has happened — all while its pump wears. Running isn't the same as fine.
An old workaround for a distinct fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." It doesn't put back what petrol has diluted, and the petrol is still inside the tank later.
Myth: "Drain that tank yourself and you are sorted." Once the motor has been run, some of the petrol is no longer inside that tank: it's in the filter and the lines, and it goes right back through your pump on your next start. Also, a can of petrol drained at the kerbside is truly hazardous.
Why petrol in a diesel occurs so easily
Nobody does it on purpose, and it is rarely carelessness. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol vehicle at all. So the error runs one way.
The moment routine stops matching your car is the moment it occurs. Hire cars, courtesy cars, and motors that are new to you. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. A rushed fill on the way to Croy with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. Your hand does what it has always done when you add rain, a phone call or a back seat full of kids.
Avoiding petrol in a diesel next time you fill up around Dullatur
- Green for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Trust the label on the pump, not the colour.
- Many vehicles state the fuel inside your filler flap or on the cap, and so check there on your first fill in a vehicle you don't know.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a home has one of each. So mark it.
- It sounds daft and it works: on the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Put the phone away. This is an easy mistake to make whilst you're thinking about something else.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Less petrol makes a thinner mix, and so stop the moment you realise — while remembering that your next step is unchanged. It is still not to start the vehicle.
Dullatur: already put petrol in a diesel?
The order of things is short, then. Don't start it, and don't switch your ignition on. If you're still on the forecourt — Tesco or anywhere else — ask the staff to help you roll the car away from the pump. Then phone 0333 366 0103 and tell us what got in, about how much, and whether it's run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Dullatur, since AdBlue brings corrosion and deposits instead of lost lubrication.
Why one petrol in a diesel job in Dullatur costs more than another
There's no honest single price for this, because the four scenarios above are four different jobs. What moves your cost is chiefly which of them you're in. Where the vehicle is matters too, and whether a technician can safely get to it, after the ratio of petrol to what the tank holds.
Before any quote, not after, come three questions: your fuel that was put in, the amount, and if it's run. That's why. A range becomes a straight figure when the replies are in.
About Dullatur
Dullatur is a small village situated on the riverside in North Lanarkshire, with a population of around 695 people. Dullatur has a mix of housing types, but detached homes are the most common, and the village is located near other small communities such as Westerwood and Carrickstone. Dullatur sits at an elevation of 78 metres, close to the city of Stirling, which is about 10.5 miles away. Dullatur is also relatively distant from major cities like London, being around 346.7 miles away.
Across North Lanarkshire and around Dullatur: fuel drain cover
Petrol in diesel call-outs in Dullatur — part of the G postcode area — go to vans that likewise cover the locations around it, Westerwood, Carrickstone and Craigmarloch included. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
Still at the petrol pump around Dullatur?
The best spot there is, then — that's where you are. Keep the car switched off, and ring.