Kents Oak: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, provided it has not been started. Petrol resting in a diesel tank does nothing to your motor till something pulls it through the fuel system — the ignition priming your pump, your starter, or the drive itself. So the fair answer to the first query anyone around Kents Oak asks, "have I wrecked it?", is normally no. Keep it like that: leave the motor off then phone Petrol in Diesel. Below, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you again.
Inside the motor: what petrol in a diesel really does
Diesel has two tasks on its way through a motor. Lubricating comes before burning; it does both. Built to very fine gaps, your injectors and your pump depend on the diesel moving through them to keep their surfaces from wearing against one another.
Poorly at the first, not at all at the second: that is petrol. The clattering comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system depends on, and any pump running on that blend is wearing itself.
Seen together, they make clear what shape the trouble has. It's circulation that causes the harm, not contact. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical fault starts.
Four scenarios our engineers see in Kents Oak: how serious is petrol in a diesel?
The best case there is: filled up, not once started. The petrol is in your tank and just that tank, and the job is a drain and a flush where the vehicle sits. This is the one scenario that can only truly occur at a forecourt, because anywhere else the car has been driven to get there.
Ignition on, or started for a moment. With the system primed, the fuel lines and filter now hold petrol that has come from your tank. Drain, flush, deal with the fuel filter: still normally straightforward.
Your pump has worked a couple of miles on thinned fuel — that is what driving the vehicle meant. The work is that tank, your lines, your filter and clean fuel through the whole system, and how hard the car was driven matters as much as how far. On the school run to Awbridge Primary School, the miles is short. Any miles on the M27, under 5 miles from Kents Oak, means the engine has worked hard throughout, and a run to Southampton, under 10 miles away, is a very different task as well.
Driven on till it complained — knocking, smoke, an uneven idle, a dead throttle. What you are hearing is your motor reporting fuel that no longer behaves like diesel. Whether it's the verge on Romsey Road, a lay-by or a side street, stop there then leave it. A vehicle stopped soon very rarely has lasting damage, as the fuel drain and the flush-through, which still come first, take care of it.
Kents Oak people and that petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a fuller tank of the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that advice supposes.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." Protection counts more on modern diesels, not less, because their fuel runs through more precise parts at higher pressure.
The myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it usually will not run, and so the driver stops — and the harm stops with them. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, while your pump grinds. Running isn't the same as fine.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, supposed for another problem. It does not put back what petrol has diluted, and the petrol is still inside your tank after that.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol lies in your filter and lines, waiting to go right back through your pump at the next start. And, a can of petrol filled by the roadside is genuinely hazardous.
How it happens: petrol in a diesel
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle mostly will not go into a petrol motor, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and only in that direction.
Routine and the vehicle falling out of step is when it takes place. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps laid out differently. A train to catch, and a hurried fill en route to Mottisfont & Dunbridge. Exactly the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. With rain, a call coming in, or a car full of children to deal with, the hand just does what it always has.
Next time you fill up in Kents Oak: preventing petrol in a diesel
- The label is what matters, and so read the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on each forecourt.
- In a vehicle you do not know, look inside the flap over your filler or at the cap before the first fill: many vehicles state the fuel there.
- Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key if a house has one of each. So label it.
- 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 petrol pump. It sounds daft and it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for the rest. Treat it as a backstop, and keep reading the petrol pump.
- The moment you realise, stop: less petrol inside the tank makes a thinner blend. What to do next does not change, though — still do not crank it.
Put petrol in a diesel around Kents Oak already?
Then the order of things is short. Leave it unstarted, with your ignition switched off as well. Ask the attendants to help you push it away from the petrol pump if you are still on the forecourt, whether that is the nearest petrol station or somewhere else. What went in, roughly how much, and if it's run: tell us that when you call 0333 366 0103.
If it was AdBlue instead of petrol, say so. That's a different problem — corrosion and deposits instead of lost lubrication — and it has its own page for Kents Oak.
Kents Oak petrol in a diesel jobs: why one costs more than another
An honest single price does not exist here: four situations, four separate jobs. Which of them you are in is mostly what moves the cost. Where the vehicle is counts too, and whether a technician can safely get to it, after the proportion of petrol to what the tank takes.
What got in, how much, and if it has run — three questions our engineers ask before costing, not after, for exactly that reason. Given the answers, you get a straight figure rather than a range.
About Kents Oak itself
Kents Oak is a suburban area in Hampshire, situated approximately 9.8 miles from Southampton and 70 miles from London. Kents Oak sits at an elevation of 83 metres, surrounded by nearby places such as Awbridge, Upper Ratley, and Lower Ratley. Kents Oak is characterised by its predominantly detached housing stock, reflecting the area's residential nature. Kents Oak remains a relatively small community, with a population of around 765 residents.
Kents Oak and Hampshire: where our fuel drain cover runs
Petrol in diesel call-outs around Kents Oak — part of the SO postcode area — go to teams that also cover the spots around it, Awbridge, Upper Ratley and Lower Ratley among them. The car doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump in Kents Oak?
The best place there is, then — that is where you are. Ring, and keep it switched off.