Dartford: Petrol in a Diesel Car? How Worried to Be
Provided it has not been started, worry less than you probably are. Everyone in Dartford begins with "have I wrecked it?", and the fair answer is generally no: petrol left inside your tank of any diesel stays harmless till priming, cranking or driving pulls it into the system. To leave the car that way, phone Petrol in Diesel and leave the engine alone. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and the way to make sure you don't repeat it.
The engine and petrol in a diesel: what happens
Passing through an engine, diesel is doing two things at once. It lubricates to begin with, and only then does it burn. Made to very fine clearances, the injectors and the pump depend on the diesel moving through them to keep their surfaces from wearing against one another.
Petrol does the first task badly and the second not at all. It is thinner than diesel and takes away the lubrication the fuel system hinges on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the rattling comes from.
The shape of the problem is plain when you put those together. Contact doesn't do the damage — movement does. Any tank with petrol in it is a fuel issue. After the pump has been running on that petrol, a mechanical fault has begun: whatever is shed by a pump that is wearing down travels downstream to your injectors with the fuel.
Dartford, petrol in a diesel: four situations, from mild to major
Fuelled, and never started: no case is better. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held inside your tank alone, it's drained and cleaned right where it stands, and nothing more is needed.
The ignition turned on, or a brief start. With the system primed, the fuel lines and filter now contain petrol that has come from the tank. That's normally still a straightforward task — a drain, a flush, and the filter seen to.
Your pump has worked a couple of miles on thinned fuel — that is what driving the vehicle does. Miles is only half of that; how hard it was driven counts equally. Either way the work includes that tank, the lines, the fuel filter and fresh fuel through the entire system. On the school run to St Anselm's Catholic Primary School, the distance is short. Very different once more: a run to London, under 25 miles away, or some mileage on the M25, under 3 miles from Dartford, where your engine never stopped working hard.
Driven on until it protested — knocking, smoke, a lumpy idle, a soft throttle. The fuel isn't behaving like diesel any more, and your engine is saying so. Stop wherever you are — the verge on Canterbury Way, a lay-by, a side street — then leave the vehicle where it is. The drain and flush-through still go first, and they sort it out: when a car is stopped soon, lasting damage is very rare.
What Dartford motorists get told about petrol in a diesel — and the stories in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — your tank just holds more of the same mixture. Percentage is not how a diesel fuel system tolerates petrol, however much that advice assumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. More precise parts and higher pressure are the way a newer diesel runs its fuel, and that makes the lubrication count more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there is no damage done." Feed diesel to a petrol motor and it normally will not run, so the motorist stops — and the harm stops with them. Whilst your pump grinds, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Running isn't the same as fine.
An outdated fix for a separate problem lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol diluted gets put back by it — and later, that tank still contains that petrol.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol sits in your filter and lines, waiting to go right back through the pump at your next start. On top of that, petrol cleared into a can by the road is genuinely hazardous.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol motor at all. So the mistake runs one way.
The moment habit stops matching your car is the moment it happens. Any motor that is new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the drive. A forecourt you know, but with its pumps arranged differently. A train to catch, and a rushed fill on the way to Stone Crossing. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Add a back seat full of children, a phone call or rain, and the hand takes over.
Next time you fill up in Dartford: preventing petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- In a car you do not know, look inside the flap over your filler or at the cap before your first fill: plenty of vehicles state the fuel type there.
- Mark your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- It seems daft and it works: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- 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 petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop checking the pump.
- The moment you realise, stop: less petrol inside that tank means a thinner blend. What to do next doesn't change, though — still don't start the vehicle.
Dartford: already put petrol in a diesel?
In that case, there's just a short order of things. Do not crank it, and do not switch your ignition on. If you are still at the forecourt — Shell or anywhere else — ask the attendants to help you roll the car away from the petrol pump. Next, 0333 366 0103. We'll ask what went in, about how much, and if it has been run.
If it was AdBlue instead of petrol, say so. That is a different issue — corrosion and deposits instead of lost lubrication — and it has its own page for Dartford.
What makes one Dartford petrol in a diesel job cost more than the next
There's no honest single price for this, because the four situations above are four different tasks. Which of them you are in is mostly what moves the cost. Two things come after that: the petrol that went in as a share of what your tank holds, then the place your car is in and whether a technician can get to it safely.
Before any quote, not after, we ask three queries: the fuel that went in, its amount, and whether it's run. That's why. With those replies, you get a straight figure rather than a range.
About Dartford and its setting
Dartford is a significant town in Kent, England, positioned inland and relatively close to the capital city. It is nestled near the border with London, with the borough of Bexley adjacent to the west. The town is also situated near the Thames Estuary, which separates it from Thurrock in Essex. Dartford serves as a key settlement in the area, surrounded by other boroughs and districts.
Fuel drain cover across Kent, Dartford included
Our teams answering petrol in diesel jobs around Dartford, in the DA postcode area, equally work the spots near it, Crossways, The Bridge and Temple Hill included. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our technicians drain, and the car doesn't need to come to us.
Still at the pump around Dartford?
Then, you couldn't be in a better spot. Keep it off. Ring.