Should You Worry? Petrol in a Diesel Car in Greatness
Probably less than you already are — as long as nobody has started the vehicle. Everyone in Greatness starts with "have I ruined it?", and the honest answer is usually no: petrol left in that tank of a diesel remains harmless till priming, cranking or driving pulls it into the system. To leave it that way, ring Petrol in Diesel then leave your motor switched off. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you again.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its route through a motor. Before it ignites, it protects — then it ignites. The high-pressure pump and your injectors are made to extremely fine tolerances, and the diesel passing through them is what keeps those surfaces from grinding against each other.
Badly at the first, not at all at the second: that is petrol. A pump working on a petrol mix is wearing itself out, since petrol is runnier than diesel and strips out the protection the fuel system depends 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 knocking comes.
Together, those make the shape of the problem plain. Contact doesn't do the damage — movement does. All a tank with petrol in it amounts to is a fuel fault. After the pump has been labouring on that petrol, a mechanical fault has started: anything shed by a pump that is grinding is carried downstream to your injectors with your fuel.
Greatness, petrol in a diesel: four cases, from mild to significant
Fuelled, and never started: nothing beats it. That petrol is inside your tank and only your tank, and the task is a drain and a flush where the vehicle sits. This is the one situation that can only truly take place on a forecourt, since anywhere else the car has been driven to get there.
A moment's running, or merely your ignition on. Petrol has come out of the tank and reached the filter and your lines, because the fuel system has been primed. Usually little more than emptying, rinsing and seeing to the filter, and so still simple.
Those few miles on the road meant your pump running on fuel thinned by petrol the whole way. Distance is only half of that; how hard it was driven counts just as much. Either way this work runs to the tank, the fuel lines, your filter and fresh fuel through the whole circuit. Driving the kids to Seal Church of England Primary School is one kind of trip. Any distance on the M26, under a mile from Greatness, means the motor working hard throughout, and a run to London, under 25 miles away, makes a very different job as well.
Driven on till it protested — rattling, smoke, an uneven idle, a dead throttle. The fuel is not acting like diesel any more, and your engine is saying so. Whether it's the verge on Highlands Park, a lay-by or a side street, stop where you are and leave it. What goes first is still the drain and flush-through, and that sorts it out, with long-term damage very rare if a vehicle is pulled over soon.
Petrol in a diesel stories Greatness motorists hear
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 fuller tank of the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. Lubrication matters more on current diesels, not less, since their fuel passes through smaller parts at higher pressure.
Myth: "If it starts and drives, there's no damage done." This is the one that fools motorists. A petrol motor fed diesel generally will not run, and so the driver stops and the damage stops with them. Whilst the pump grinds, a diesel fed petrol usually starts, ticks over and drives away as if nothing has happened. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a separate problem. None of what petrol thinned gets put back by it — and later, the tank still holds the petrol.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol lies in the fuel filter and lines, ready to go right back through the pump at the next start. Also, a can of petrol filled by the roadside is truly dangerous.
How it happens: petrol in a diesel
It is rarely carelessness, and nobody does it on purpose. A diesel nozzle mostly won't fit a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and only in that direction.
The moment routine stops matching the vehicle is the moment it happens. Hire cars, courtesy cars, and vehicles that are new to you. Two motors on one driveway, one petrol, one diesel. Your normal forecourt, its pumps now in a different order. A rushed fill on the way to Bat & Ball with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Passat in front of you on the forecourt for its first tank — that's when. Add a back seat full of children, a phone call or rain, and habit takes over.
Greatness people: 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. Check the pump's label; the colour is just a clue.
- Inspect the filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on the first fill in a vehicle you don't know.
- One of each in the household? Mark the key to the diesel — a bright fob, a sticker — since meaning to remember is not enough.
- 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 seems daft and it works.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away and keep your mind on the pump.
- Add-on devices are available for vehicles without one, and some diesels are built with a filler that won't accept a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- Less petrol makes a weaker mixture, and so stop as soon as you notice — though remembering that your next stage is unchanged. It is still not to start it.
Greatness: already put petrol in a diesel?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. Ask the staff to help you push it clear of the petrol pump if you are still on the forecourt, whether that's Esso or anywhere else. Next, 0333 366 0103. We will ask what was put in, about how much, and if it has been run.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Greatness page.
What makes one Greatness petrol in a diesel task cost more than the next
The four situations above are four different jobs, so no single price for this would be fair. Mostly, your cost shifts with which situation you are in. The share counts next, meaning how much of that tank is petrol, followed by the location of your car and whether getting to it is safe for our van.
Three queries come first, before any quote, rather than after — what was put in, how much, has it run — and this is the reason. Given the answers, you get a straight figure rather than a range.
About Greatness itself
Greatness is a suburban area in Kent, situated approximately 21 miles southeast of central London. Greatness sits at an elevation of around 91 metres, amidst the rolling countryside of the Weald of Kent. Greatness is characterised by its predominantly detached housing stock and is located near the villages of Seal and Sevenoaks, with Wildernesse and Childsbridge also in the vicinity.
Across Kent and in Greatness: fuel drain cover
Our teams answering petrol in diesel calls around Greatness, in the TN postcode area, also work the locations around it, Seal, Wildernesse and Childsbridge included. We drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Greatness: still at the pump?
Nothing beats it: that's where you now are. Phone, and leave it switched off.