How Worried Should You Be? Petrol in a Diesel Car in Lower Largo
Unstarted? Then less anxious than you likely are. Petrol sitting in a diesel tank does nothing to the motor until something draws it through your fuel system — the ignition priming the pump, your starter, or driving itself. So the honest answer to the first question everyone around Lower Largo asks, "have I ruined it?", is usually no. Petrol in Diesel is who to ring, with your motor left off, and so it remains that way. The remainder of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
The motor and petrol in a diesel: what happens
Diesel does two tasks on its way through a motor. Oiling comes before burning; it does both. Very fine gaps go into the fuel injectors and the high-pressure pump, and only your diesel running through stops their surfaces grinding together.
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 precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication your system depends on, and any pump working on such a blend is wearing itself.
Seen together, they show the shape the problem takes. The harm is done by movement, not by contact. Petrol in the tank is a fuel issue. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
Four scenarios our engineers see in Lower Largo: how bad is petrol in a diesel?
The best case there can be: filled up, not once started. Only your tank has petrol in it, so the job is emptying the tank and purging your system where your car sits. This situation can only really occur on a forecourt: anywhere else, the car got there by being driven.
A brief spell of running, or merely the ignition on. Petrol has left that tank and got to your filter and the fuel lines, since your system has been primed. Drain, flush, see to the filter: still usually straightforward.
A few miles driven, and the pump has spent each of them running on weakened fuel. Tank, lines, filter, then fresh fuel put through the whole system: that is this work, and the way your car was driven counts as much as the mileage. On the school run to the local primary school, the mileage is small. Any miles on the M90, under 25 miles from Lower Largo, means the motor has worked hard throughout, and a run to Dundee, under 25 miles away, makes a very different job as well.
Driven on until it protested — clattering, smoke, a lumpy idle, a soft throttle. What you are hearing is the engine signalling fuel that no longer runs like diesel. Whether it's the verge on Main Street, a lay-by or a side street, stop there and leave it. Lasting damage is very rare when a car is pulled over early, and the drain and flush that still go first sort it out.
Petrol in a diesel myths Lower Largo motorists hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. A diesel fuel system does not tolerate petrol by percentage in the way that guidance presumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. More precise components and higher pressure are the way a current diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more people than any other. Diesel in a petrol motor usually leaves a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it generally starts, idles and drives away as if nothing happened — all the while its pump wears. Being able to run is not proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate problem. It does not put back what petrol has weakened, and that petrol is still in the tank after that.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol sits in your filter and lines, waiting to go right back through your pump on your next start. It's also truly risky to drain petrol into a can by the roadside.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle mostly will not go into a petrol motor, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and just in one direction.
When habit and the car stop matching, it happens. Any car that's new to you — a hire car, on loan as a courtesy car, or just bought. Two vehicles on one drive, one petrol, one diesel. Your normal forecourt, its pumps suddenly in a different order. Fuelling up in a rush en route to Leven, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Throw in rain, a phone call or a back seat full of children, and your hand does what it has always done.
Avoiding petrol in a diesel next time you fill up in Lower Largo
- Check the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what matters.
- Inspect the filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on your first fill in a motor you don't know.
- Label your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" out loud. Daft, yes, but it does the trick.
- Mistakes like this are simple to make whilst your mind is on something else, and so your phone goes away.
- Some diesels come with a filler designed to block 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 pump.
- Spotting it halfway? Stop at once. A weaker mix follows from less petrol in the tank, yet your next stage remains the same: don't start it.
Petrol already in a diesel around Lower Largo? Start here
Then the order of things is short. Do not start the car, and do not turn the ignition on. Yet at the forecourt, at Sainsbury's or anywhere else? Ask the attendants to help you push the vehicle clear of the petrol pump. What went in, about how much, and if it has run: tell us that when you ring 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Lower Largo has a page just for it.
What makes one Lower Largo petrol in a diesel job cost more than the next
An honest single price does not exist here: four scenarios, four separate jobs. Which of them you're in is chiefly what shifts the cost. After that it is the proportion — how much petrol got in against how much that tank holds — and after that where the car is and whether a van can reach it safely.
What went in, how much, and if it has run — three questions our engineers ask before costing, not after, for exactly that reason. Given the answers, there is a straight figure instead of a range.
About Lower Largo itself
Lower Largo is a small coastal village in Fife, situated on the north shore of the Firth of Forth, with the nearby towns of Lundin Links and Upper Largo. Lower Largo has a population of around 991 people, living in predominantly detached housing. Lower Largo sits at a low elevation of 12 metres above sea level, close to the beaches and scenic coastal paths of the area.
Lower Largo and Fife: where our fuel drain cover runs
Our teams answering petrol in diesel calls around Lower Largo, in the KY postcode area, also work the locations near it, Drummochy, Upper Largo and Lundin Links included. The vehicle doesn't need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the petrol pump in Lower Largo, still?
Nothing beats it: that's where you now are. Turned off it remains; then phone.