Longford: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you probably feel. "Have I wrecked it?" is the first thing everyone around Longford asks, and the truthful answer is normally no, because petrol left in a diesel tank harms nothing until it is dragged through your fuel system — by ignition priming, by your starter, or by being driven. To leave it that way, call Petrol in Diesel then leave the engine switched off. Further down, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to the engine
Diesel does two jobs on its way through an engine. Before it burns, it protects — then it burns. Extremely fine gaps go into the injectors and your high-pressure pump, and only the diesel running through stops those surfaces grinding together.
The second task petrol doesn't do at all, and the first it does poorly. A pump working on a petrol mixture is wearing itself out, since petrol is thinner than diesel and strips out the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where any rattling comes.
The shape of the problem is clear when you put those together. The harm is done by movement, not by contact. Any tank with petrol in it is a fuel fault. Whatever a worn pump sheds travels on, borne by the fuel, into your injectors further along, which is why a pump that has been working on that petrol is where a mechanical fault begins.
Petrol in a diesel around Longford: how serious is it? Four situations
Fuelled but never started — as good as it gets. Just that tank has petrol in it, so the job is clearing the tank and flushing your system where the vehicle sits. This scenario can only truly occur at a forecourt: anywhere else, the vehicle got there by being driven.
Started for a moment, or just your ignition on. Petrol has come out of your tank and reached the filter and the lines, because the system has been bled. Drain, flush, see to the fuel filter: still normally straightforward.
A few miles driven, and the pump has spent every one of them running on diluted fuel. How hard the vehicle was driven matters as much as how far, and the work takes in that tank, the fuel lines, your filter and fresh fuel through the entire system. The school run to Dunton Green Primary School is one matter. A run as far as London, under 25 miles away, is a very different job. So is any miles on the M26, under a mile from Longford, where the engine has been running hard the whole time.
Rattling, a ragged idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the engine reporting fuel that no longer runs like diesel. Whether it's the verge on Crescent Cottages, a lay-by or a side road, stop where you are and leave it. Lasting damage is very rare if a vehicle is pulled over soon, and the drain and flush that still go first deal with it.
Longford motorists and that petrol in a diesel myths they hear
False: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mixture is all you get, because topping up removes nothing. That advice presumes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel runs its fuel through more precise parts at higher pressure, which makes the lubrication matter more, not less.
"It starts, it drives, so there is no harm" — the myth that trips up most people than any other. Diesel in a petrol motor generally means a motor that won't run: the motorist stops, and so does the harm. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, whilst your pump wears. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old fix for a different issue. None of what petrol weakened is put back by it — and afterwards, the tank still holds that petrol.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol sits in the fuel filter and lines, ready to go straight back through the pump on the next start. And, a can of petrol drained by the roadside is genuinely hazardous.
Why petrol in a diesel takes place so easily
It is seldom carelessness, and nobody does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol car. That's how the forecourt makes it easy.
The moment routine stops matching your car is the moment it occurs. A motor that's new to you — hired, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the driveway. Your usual forecourt, its pumps now in a different order. Racing for a train outside Dunton Green and filling up en route. A new-to-you diesel Nissan Qashqai, its first fuelling, and a motorist accustomed to petrol: exactly when it happens. With rain, a call arriving, or a car full of children to deal with, the hand simply does what it always has.
Longford motorists: how to avoid petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is only a hint.
- In a car you do not know, look inside the flap over the filler or at the cap before your first fill: many vehicles print the fuel type there.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of intending to remember, for a household with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds silly 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 petrol pump.
- Some diesels come with 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 checking the petrol pump.
- The moment you notice, stop: less petrol in that tank makes a weaker mix. What to do next doesn't change, though — still do not fire it up.
Already put petrol in a diesel around Longford?
The order of things is short, then. Do not turn the ignition on, and don't fire it up. The staff on the forecourt — whether at Tesco itself or wherever you filled up — will usually help push it away from the pump if you ask. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Longford, since AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel task around Longford costs more than another
Four separate jobs sit behind the four scenarios above — which is why there is no fair single quote. Chiefly, the cost shifts with which one you are in. Where your car is matters too, and whether a technician can safely reach it, after the share of petrol to what the tank takes.
That is why we ask three queries before pricing rather than after: what was put in, how much, and whether it's run. Those replies turn a range into a straight figure.
About Longford itself
Longford is a suburban area in Kent, situated lakeside with an elevation of 79 metres, and is located near several other communities including Riverhead and Dunton Green. Longford is characterized by its predominant housing type, which is flat, and is home to a population of approximately 3800 residents. Longford sits within the wider South East region, close to the nearby city of London, which is about 19 miles away.
Across Kent and around Longford: fuel drain cover
Longford waits in the TN postcode area, and the vans that answer petrol in diesel calls there work the locations around it as well — Riverhead, Dunton Green and Chipstead among them. Our engineers drain wherever the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Longford and still at the petrol pump?
Then you are in the best place there is. Phone, and leave it turned off.