Hamstreet: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as no one has started the car. Everyone around Hamstreet starts with "have I ruined it?", and the fair answer is normally no: petrol resting inside the tank of a diesel stays harmless till priming, cranking or driving draws it into the system. To leave it that way, ring Petrol in Diesel then leave your engine switched off. Further down, this page sets out what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
Inside the motor: what petrol in a diesel really does
On its way through an engine, diesel does two tasks. It combusts, and before it ignites it protects. Extremely fine tolerances go into the fuel injectors and the high-pressure pump, and just the diesel flowing through stops their surfaces grinding together.
Of these two tasks, petrol handles the first poorly and the second not at all. The rattling comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the lubrication your system rests on, and any pump working on that mix is wearing itself.
The shape of the problem is plain once you put those together. Not contact but circulation is what does the damage. Any tank with petrol in it is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors further along, which is why a pump that has worked on the petrol is where a mechanical problem starts.
Hamstreet, petrol in a diesel: four situations, from mild to significant
Fuelled up, never started. The best case there is. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With that petrol kept inside your tank alone, it's cleared and flushed right where it stands, and nothing more is needed.
A brief spell of running, or merely the ignition on. Once primed, the system has drawn petrol from your tank as far as the fuel filter and the fuel lines. That's normally still a straightforward task — a drain, a flush, and the filter seen to.
A couple of miles driven, and the pump has spent every one of them working on diluted fuel. Miles is only half of it; how hard it was driven matters just as much. Either way the work runs to the tank, your lines, your filter and fresh fuel through the whole circuit. Driving the children to Hamstreet Primary Academy is one kind of trip. Very different once more: a trip to Canterbury, under 25 miles away, or any miles on the M20, under 10 miles from Hamstreet, where the engine never stopped labouring hard.
Driven until it protested. Clattering, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is the engine signalling fuel that no longer acts like diesel. Pull up on the spot — on the verge on Ashford Road, at the kerb, down a side road — and don't move it again. A car pulled over quickly very seldom has permanent damage, since the fuel drain and the flush, which still come first, deal with it.
Myths Hamstreet people hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It doesn't. Nothing comes out when you top up — the tank just holds more of the same blend. That guidance assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Lubrication counts more on newer diesels, not less, since their fuel runs through more precise components at higher pressure.
Myth: "If it starts and drives, there is no harm done." This is the one that catches drivers. The motorist of a petrol motor fed diesel usually stops, because it will not run, and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Running is not the same as fine.
An old workaround for a distinct problem is behind this one. Myth: "Add some two-stroke oil and drive it home." None of what petrol weakened is put back by it — and later, the tank still contains that petrol.
Myth: "Drain that tank yourself and you are sorted." Once the engine has been run, some of that petrol is no longer inside your tank: it's in the filter and the fuel lines, and it goes straight back through your pump at your next start. Besides, petrol drained into a can by the road is genuinely dangerous.
How it happens: petrol in a diesel
Carelessness is rarely the cause, and no one means to do it. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it easy, and the slip runs one way.
Routine and the car getting out of step is how it takes place. A new motor, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. A well-known forecourt with the pumps in a different order. A train to catch, and a hurried fill en route to Ham Street. The first fill-up in a diesel Skoda Octavia after years of driving petrol is precisely the moment it occurs. Your hand does what it has always done when you add rain, a phone call or a back seat full of kids.
Hamstreet drivers: how to prevent petrol in a diesel next time
- The label is what counts, and so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- The first fill in a new motor is the time to check your filler flap — inside it, or on the cap, plenty of motors state the fuel they take.
- Label the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It sounds daft and it works.
- Mistakes like this are simple to make whilst your mind is on something else, and so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to block a petrol nozzle, and add-on devices are available for the rest. Count it as a safety net, and keep checking the pump.
- Less petrol makes a thinner mixture, and so stop the moment you notice — while remembering that your next step is unchanged. It is still not to start it.
Petrol already in a diesel in Hamstreet? Start here
Then the order of things is brief. Leave it unstarted, with the ignition switched off as well. Ask the staff to help you push it away from the pump if you are still on the forecourt, whether that is Tesco or somewhere else. Call 0333 366 0103 next, with three answers — the fuel, the approximate volume, and if it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate problem — Hamstreet has a page just for it.
What makes one Hamstreet petrol in a diesel task cost more than the next
A fair single price does not exist here: four scenarios, four separate tasks. Mostly, your cost moves with which one you are in. Two things come after that: the petrol that went in as a share of what the tank takes, then the spot the car is in and whether our van can reach it safely.
That is why our technicians ask three questions before pricing instead of after: what was put in, how much, and whether it has run. The answers turn a range into a straight figure.
About Hamstreet itself
Hamstreet is a small village in Kent, situated on the banks of the River Rother at a low elevation of around 6 metres. Hamstreet lies near the villages of Orlestone and Warehorne, and is connected to the larger town of Canterbury, which is approximately 17 miles away. Hamstreet has a mix of housing types, but is predominantly composed of terraced homes, reflecting its history of development along the river. Hamstreet is located within the South East region, about 52 miles from London.
Fuel drain cover across Kent, Hamstreet included
Hamstreet rests in the TN postcode area, and the teams that answer petrol in diesel jobs there work the locations around it as well — Orlestone, Warehorne and The Leacon among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places we work, and the car does not need to move to us.
Hamstreet: still at the pump?
Then you're in the best place there can be. Keep it off. Call.