Petrol in a Diesel Car in Blackhouse: How Worried Should You Be?
Likely less than you already are — provided nobody has started it. "Have I wrecked it?" is the first question everyone in Blackhouse asks, and the truthful answer is usually no, since petrol resting in a diesel tank harms nothing until it is drawn through your fuel system — by ignition priming, by the starter, or by being driven. Keep it that way: leave your engine off and call Petrol in Diesel. What petrol actually 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 remainder of this page.
The motor and petrol in a diesel: what goes on
Diesel does two tasks on its way through an engine. Before it combusts, it lubricates — then it ignites. The high-pressure fuel pump and your injectors are designed to very fine gaps, and your diesel passing through them is what stops those surfaces from grinding against one another.
Poorly at the first, not at all at the second: that's petrol. It's runnier than diesel and removes the lubrication your fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
Put those together and the shape of the trouble is clear. Not contact but movement is what does the damage. Petrol in the tank is a fuel issue. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Petrol in a diesel in Blackhouse: how serious is it? Four situations
Fuelled but never started — the best it gets. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With the petrol held in the tank alone, it's drained and cleaned right where it stands, and nothing more is needed.
The ignition turned on, or a short start. Petrol has left your tank and reached the filter and the fuel lines, because the fuel system has been primed. Still usually straightforward: drain, flush, and your filter dealt with.
Some miles driven, and the pump has spent each of them labouring on weakened fuel. The work is that tank, the lines, the fuel filter and fresh fuel through the entire circuit, and how hard your car was driven counts as much as how far. On the school run to the local primary school, the distance is short. Any miles on the M90, over 50 miles from Blackhouse, means the motor working hard throughout, and a run to Aberdeen, under 50 miles away, makes a very different task as well.
Driven until it protested. Knocking, a ragged idle, smoke, a throttle that has gone soft. That's the motor telling you its fuel has stopped acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Catto Way. What goes first is still the fuel drain and flush, and that deals with it, with long-term damage very uncommon when a vehicle is pulled over soon.
What Blackhouse people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." A fuller tank of the same mix is all you get, since topping up removes nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance supposes.
"Current diesels can handle a little petrol" — a myth, and closer to the opposite. Lubrication matters more on modern diesels, not less, because their fuel passes through finer parts at higher pressure.
Myth: "If it starts and drives, there's no harm done." This is the one that catches motorists. Diesel in a petrol motor generally leaves a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally fires up, ticks over and pulls away as if nothing has happened — all the while its pump is wearing. Running doesn't mean fine.
Not so: a two-stroke additive lets you to drive home. It was an old fix, meant for another problem. None of what petrol weakened gets put back by it — and later, that tank still holds the petrol.
The next start draws petrol back round your pump from the lines and the fuel filter, where some of it ends up once the engine has run. That's why draining the tank yourself doesn't sort it — a myth. Besides, petrol drained into a can by the road is truly risky.
How petrol ends up: petrol in a diesel
It's rarely carelessness, and no one does it on purpose. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly won't fit a petrol car. That's how the forecourt makes it straightforward.
The moment routine stops matching the vehicle is the moment it takes place. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A hurried fill on the way to the nearest station with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
Next time you fill up in Blackhouse: preventing petrol in a diesel
- The label is what counts, and so check the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on every forecourt.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: plenty of cars print the fuel type there.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, in a household with one of each.
- It sounds daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Put the phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the petrol pump.
- Stop as soon as you notice. Less petrol in that tank means a weaker mix. It does not change what to do next, which is still not to start the car.
Put petrol in a diesel around Blackhouse already?
The order of things is brief, then. Don't start it, and don't switch your ignition on. The staff at the forecourt — whether at Morrisons itself or wherever you filled up — will normally help roll it clear of the pump if you ask. Then ring 0333 366 0103 and tell us what was put in, about how much, and if it's run.
Corrosion and deposits form the problem with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Blackhouse page.
Why one petrol in a diesel task in Blackhouse costs more than another
The four situations above are four different jobs, so no single price for this would be fair. Which of them you are in is mostly what shifts the cost. Beyond that it's the share — how much petrol went in against how much the tank takes — and then where your car is and whether our van can reach it safely.
Three questions come first, before quoting, instead of after — what was put in, how much, has it run — and that is the reason. Those answers are what turn a range into one firm number.
About Blackhouse and where it is
Blackhouse is a suburban area situated on the coast of Aberdeenshire, with an elevation of 23 metres above sea level. Blackhouse lies approximately 27 miles north of Aberdeen and is characterised by its predominantly semi-detached housing stock. Blackhouse is one of several residential areas in the region, including nearby Coplandhill and Grange Gardens. Blackhouse has a population of around 4497 people, making it a modestly sized community.
Fuel drain cover across Aberdeenshire, Blackhouse included
Our vans answering petrol in diesel calls in Blackhouse, in the AB postcode area, equally work the spots around it, Coplandhill, Grange Gardens and Middle Grange among them. Our engineers drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Blackhouse: still at the petrol pump?
The best position there is, then — that's where you are. Keep it off. Call.