How Worried Should You Be? Petrol in a Diesel Car in East Malling
Likely less than you already are — as long as no one has started the vehicle. "Have I wrecked it?" is the first question anyone in East Malling asks, and the honest answer is normally no, because petrol resting in a diesel tank hurts nothing till it's dragged through your fuel system — by ignition priming, by your starter, or by driving. To keep it like that, call Petrol in Diesel and leave your motor switched off. Further down, this page sets out what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
The motor and petrol in a diesel: what happens
Passing through an engine, diesel does two jobs at once. It burns, and before it burns it lubricates. Extremely fine clearances go into the fuel injectors and the high-pressure pump, and just the diesel flowing through stops those surfaces grinding together.
The second task petrol doesn't do at all, and the first it does badly. It's runnier than diesel and strips away the lubrication the fuel system rests on, 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.
The shape of the problem is clear when you put those together. Contact does not do the damage — movement does. A tank with petrol in it is a fuel issue. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Four scenarios our engineers see in East Malling: how serious is petrol in a diesel?
Fuelled up, not once started. The best case there is. Just that tank has petrol in it, and so the task is draining that tank and rinsing the system where your car sits. This scenario can only truly take place at a forecourt: anywhere else, your car got there by being driven.
Started for a second, or only the ignition on. The fuel system has been bled, and so petrol has left your tank and got to the filter and the lines. That is usually still a simple job — a drain, a flush, and the fuel filter dealt with.
Driven a few miles. Now the pump has spent these miles running on diluted fuel. How hard your car was driven matters as much as how far, and the work covers the tank, the lines, your filter and clean fuel through the whole circuit. Short trips, such as the school run to Lift St James the Great, are one thing. Any distance on the M20, under 3 miles from East Malling, means the engine working hard throughout, and a run to Southend-on-Sea, under 25 miles away, is a very different job too.
Driven until it complained. Clattering, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is the engine signalling fuel that no longer acts like diesel. Stop on the spot — on the verge on New Road, at the kerb, down a side road — and don't move it. The drain and flush-through still come first, and they sort it out: when a vehicle is pulled over early, lasting damage is very uncommon.
What East Malling drivers 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." Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: a current diesel copes with a bit of petrol. If anything, the opposite. Lubrication matters more on modern diesels, not less, because their fuel passes through more precise components at higher pressure.
One myth that catches people out: if it starts and drives, it must be unharmed. Any petrol engine fed diesel normally will not run, and so the driver stops and the damage stops with them. While 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.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct problem. None of what petrol weakened gets put back by it — and afterwards, the tank still holds the petrol.
If the engine has run, part of that petrol sits in the fuel filter and your lines, not that tank — and your next start pulls it right back through your pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. Emptying petrol into a can at the roadside is also genuinely dangerous.
How does petrol in a diesel take place?
Carelessness is rarely the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the slimmer 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 vehicle at all. So the error runs one way.
It takes place when habit and the car stop matching. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A rushed fill on the way to the nearest station with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it takes place. 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 around East Malling: preventing petrol in a diesel
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Trust the label on the petrol pump, not the colour.
- Check the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in any vehicle you do not know.
- Mark your key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds daft. It works.
- 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.
- Add-on devices are available for cars without one, and some diesels come with a filler that won't accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside the tank makes a weaker blend. What to do next does not change, though — still don't fire it up.
Put petrol in a diesel around East Malling already?
Then the order of things is short. Don't switch the ignition on, and do not crank it. Ask the attendants to help you roll it away from the petrol pump if you are still on the forecourt, whether that is Esso or somewhere else. Then phone 0333 366 0103 and tell us what got in, about how much, and whether it's run.
If it was AdBlue and not petrol, say so. That's a separate fault — corrosion and deposits rather than lost lubrication — and it has its own page for East Malling.
Why one petrol in a diesel job around East Malling costs more than another
The four situations above are four separate tasks, so no single price for this would be honest. Chiefly, your cost shifts with which one you are in. After that it is the share — how much petrol got in against how much the tank takes — and after that where the car is and whether our van can get to it safely.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and this is the reason. Those replies turn a range into a straight figure.
About East Malling
East Malling is a village in Kent, situated on the banks of the River Medway at an elevation of 34 metres. East Malling has a mix of old and new housing, with detached homes being the predominant type, and is located near to Mill Street, Well Street, and Larkfield. East Malling is close to the town of Southend-on-Sea, approximately 21 miles away, and is also within commuting distance of London, which is around 29 miles to the west. East Malling has a population of around 1007 people, according to recent estimates.
Fuel drain cover around East Malling and across Kent
Petrol in diesel jobs around East Malling — part of the ME postcode area — go to vans that likewise cover the places about it, Mill Street, Well Street and Larkfield included. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
In East Malling and still at the pump?
Then you're in the best spot there is. Keep it off. Ring.