Petrol in a Diesel Car in Seatown: How Worried Should You Be?
Far less than you likely are, provided it hasn't been started. Till your ignition primes your pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank simply rests there and does nothing. Which makes the honest reply to the first Seatown query — "have I ruined it?" — normally no. Keep it that way: leave your motor off then ring Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it has travelled, and how to keep it from happening a second time: that's the rest of this page.
Inside the engine: what petrol in a diesel does
On its way through a motor, diesel has two tasks. Before it ignites, it protects — and then it combusts. Designed to very fine tolerances, the fuel injectors and the pump rely on your diesel moving through them to keep their surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on the mixture to wear itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Combined, those make the shape of the trouble clear. The damage is done by movement, not by contact. A tank with petrol in it is a fuel problem. Once the pump has been labouring on that petrol, a mechanical fault has started: whatever is shed by a pump that is grinding travels downstream to the injectors with the fuel.
Seatown, petrol in a diesel: four situations, from mild to significant
Filled up, and never started: nothing beats it. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held in your tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
A moment's running, or merely your ignition on. Once primed, the fuel system has drawn petrol from the tank up to the filter and the fuel lines. Still normally straightforward: drain, flush, and the filter sorted.
The pump has worked a few miles on weakened fuel — that is what driving it meant. The work is that tank, the fuel lines, your filter and fresh fuel through the entire circuit, and how hard the vehicle was driven counts as much as how far. On the school run to the local primary school, the miles is short. A run as far as Inverness, under 50 miles away, is a very different job. So is any mileage on the M90, over 50 miles from Seatown, where the engine has been running hard the whole time.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The engine is telling you the fuel is no longer acting like diesel. Stop on the spot — on the verge on Moray Street, at the kerb, down a side road — and don't move it again. A vehicle pulled over early very rarely has long-term damage, since the fuel drain and the flush, which still come first, deal with it.
What Seatown motorists get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that guidance presumes.
Not so: a current diesel copes with a bit of petrol. Rather, the reverse. Finer parts and higher pressure are the way a newer diesel runs its fuel, and that makes the protection count more, not less.
This is the one that fools people. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol motor and it normally won't run, and so the motorist stops — and the damage stops with them. While your pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Fine and running are not the same at all.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, meant for another fault. None of what petrol diluted is put back by it — and later, your tank still holds the petrol.
Myth: "Drain the tank yourself and you are sorted." Once your engine has run, some of that petrol is no longer in that tank: it is in the filter and the fuel lines, and it goes straight back through your pump on your next start. And, a can of petrol filled by the roadside is genuinely hazardous.
How does petrol in a diesel take place?
It is seldom carelessness, and nobody does it on purpose. A diesel nozzle mostly will not go into a petrol vehicle, but the slimmer petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake easy, and only in one direction.
It takes place when habit and the vehicle stop matching. Hire cars, courtesy cars, and vehicles that are new to you. Two motors on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. A train to catch, and a rushed fill on the way to Elgin. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it happens. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Seatown drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is just a hint.
- Plenty of vehicles state the fuel type inside your filler flap or on the cap, and so check it on the first fill in any motor you don't know.
- Good intentions count for less than a sticker or a fob in a vivid colour on your diesel's key when a household has one of each. So mark it.
- 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 petrol pump. It sounds daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the pump.
- Some diesels have a filler built to block a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol in your tank makes a weaker mix. It does not change what to do next, which is still not to start the vehicle.
Petrol already in a diesel in Seatown? Start here
In that case, there is just a short order of things. Don't start it, and do not turn your ignition on. Ask the attendants to help you roll it away from the petrol pump if you're still at the forecourt, whether that's the nearest petrol station or anywhere else. What was put in, roughly how much, and if it has run: tell us those when you phone 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — Seatown has a page just for it.
Seatown petrol in a diesel jobs: why one costs more than another
The four situations above are four different tasks, so no single quote for this would be fair. The situation itself does most of the work of moving your cost. Two things come after that: the petrol that went in as a proportion of what your tank holds, then the place the car is in and whether a technician can reach it safely.
That is why our engineers ask three queries before quoting instead of after: what went in, how much, and if it's run. The answers turn a range into a straight figure.
About Seatown itself
Seatown is a coastal suburban area in Moray, situated near the towns of Lossiemouth and Branderburgh. Seatown has a population of around 2320 people and is characterized by its semi-detached housing stock. Seatown sits at a low elevation of approximately 5 metres above sea level, looking out onto the Moray Firth. Seatown is located near Stotfield and is within commuting distance of the city of Inverness.
Seatown and Moray: where our fuel drain cover runs
Lossiemouth, Branderburgh and Stotfield are among the locations around Seatown that the same vans work, answering petrol in diesel jobs across Seatown's IV postcode area. Our technicians drain wherever the vehicle 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 in Seatown, right now?
Then, you could not be in a better place. Keep the car switched off, and ring.