Petrol in a Diesel Car in Headstone: How Worried Should You Be?
Far less than you likely are, if it hasn't been started. Everyone in Headstone begins with "have I wrecked it?", and the fair answer is generally no: petrol left inside your tank of any diesel remains harmless till priming, cranking or driving pulls it into the system. Leave your engine off then phone Petrol in Diesel — that is how you keep it like that. The remainder of this page sets out what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Inside the motor: what petrol in a diesel does
Passing through an engine, diesel is doing two things at once. It combusts, and before it burns it lubricates. Your high-pressure pump and the injectors are designed to very fine clearances, and the diesel passing through them is what keeps those surfaces from wearing down against one another.
Of those two jobs, petrol manages the first badly and the second not at all. It's thinner than diesel and strips away the lubrication your fuel system depends 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 reverse of what a diesel needs from its fuel. That is where the knocking comes from.
Taken together, they show what shape the problem takes. It is movement that does the damage, not contact. Where that petrol is only inside your tank, it is a fault of fuel, nothing more. Once the pump has been running on that petrol, a mechanical issue has begun: whatever is shed by a pump that's wearing is carried onward to the injectors with your fuel.
Petrol in a diesel around Headstone: how bad is it? Four situations
Filled up, and never started: no case is better. Just your tank has petrol in it, and so the job is draining your tank and rinsing the system where the vehicle sits. This situation can only truly occur on a forecourt: anywhere else, the car got there by being driven.
Your ignition switched on, or a brief start. Once primed, your system has drawn petrol from the tank up to the fuel filter and the lines. Normally nothing more than emptying, flushing and sorting the filter, and so still straightforward.
Your pump now spent a couple of miles on diluted fuel — that's what driving the vehicle does. The work is your tank, the lines, the filter and fresh fuel through the whole circuit, and how hard your car was driven matters as much as how far. On the school run to Pinner Park Primary School, the distance is short. Any distance on the M1, under 5 miles from Headstone, means your engine has worked hard throughout, and a run to St Albans, under 15 miles away, makes a very different task too.
Driven on until it complained — rattling, smoke, a ragged idle, a dead throttle. The fuel isn't acting like diesel any more, and the motor is telling you. Stop on the spot — on the verge on Holmdene Avenue, at the kerb, down a side road — and don't move it again. The fuel drain and flush-through still go first, and they take care of it: when a car is pulled over soon, long-term damage is very unusual.
Petrol in a diesel stories Headstone drivers hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed when you top up — that tank just holds more of the same blend. Percentage is not how a diesel fuel system copes with petrol, whatever that guidance presumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. Lubrication counts more on modern diesels, not less, since their fuel passes through more precise components at higher pressure.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel normally has no choice but to stop, since 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, as it usually will; meanwhile the pump wears. Fine and running aren't the same at all.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, supposed for another issue. The petrol is still in the tank afterwards, and what it has thinned isn't put back.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in your filter and lines, waiting to go right back through your pump at your next start. On top of that, petrol cleared into a can by the road is truly dangerous.
Petrol in a diesel: how does it happen?
Nobody does it on purpose, and it is seldom carelessness. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol car. That's how the forecourt makes it easy.
Habit and the car getting out of step is when it occurs. A new vehicle, a hire car or a courtesy car. Households running one of each, petrol and diesel. Your usual forecourt, its pumps now in a different order. A rushed fill en route to Headstone Lane with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. Add a back seat full of kids, a phone call or rain, and the hand takes over.
How to prevent petrol in a diesel at your next fill-up in Headstone
- Green for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Trust the label on the petrol pump, not the colour.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of vehicles print the fuel type there.
- Mark your key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- 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 sounds silly and it does the trick.
- Tuck the phone away. This is an easy mistake to make while you are thinking about something else.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- The moment you notice, stop: less petrol inside that tank makes a thinner mixture. What to do next doesn't change, though — still do not fire it up.
Petrol already in a diesel in Headstone? Begin here
Short and simple, then, is the order of things. Don't turn the ignition on, and do not crank it. If you're still on the forecourt — Esso or anywhere else — ask the attendants to help you push the vehicle away from the petrol pump. What was put in, roughly how much, and whether it has run: tell us those when you phone 0333 366 0103.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Headstone page.
Why one petrol in a diesel task around Headstone costs more than another
There is no fair single quote for this, since the four situations above are four different tasks. The situation itself does most of the work of moving your cost. The ratio matters next, meaning how much of the tank is petrol, and then the position of the vehicle and whether getting to it is safe for a technician.
That's why our engineers ask three queries before costing instead of after: what went in, how much, and whether it's run. The answers change a range into a straight figure.
About Headstone
Headstone is a suburban area in northwest London, situated near the River Pinn and close to the borders of Hertfordshire. Headstone has a relatively low elevation of around 60 metres and is characterized by its semi-detached housing stock. Headstone is located near several other suburban areas, including North Harrow, Pinner, and Hatch End, and is within commuting distance of central London. Headstone is also relatively close to the city of St Albans, which is about 11 miles away.
Fuel drain cover in Headstone and across Greater London
North Harrow, Pinner and Hatch End are among the places around Headstone that the same teams work, answering petrol in diesel jobs across Headstone's HA postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians work, and your car doesn't need to come to us.
In Headstone and still at the pump?
Then, you could not be in a better place. Turned off it remains; then call.