Should You Worry? Petrol in a Diesel Car in Deans
Provided it hasn't been started, you can worry far less than you probably are. Everyone in Deans begins with "have I ruined it?", and the honest answer is normally no: petrol left inside the tank of any diesel remains harmless until priming, cranking or driving pulls it into your fuel system. To keep it that way, call Petrol in Diesel then leave the motor alone. Further down, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what happens
Diesel does two tasks on its way through an engine. It ignites, and before it burns it lubricates. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from grinding against each other is your diesel passing through them — they are made to extremely fine gaps.
Badly at the first, not at all at the second: that is petrol. A pump working on a petrol mixture is wearing itself out, because petrol is thinner than diesel and takes away the protection your fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the rattling starts.
Seen together, they show the shape the trouble takes. Contact doesn't do the harm — circulation does. Petrol in the tank is a fuel fault. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors downstream.
Four situations we see in Deans: how bad is petrol in a diesel?
Fuelled but never started — the best it gets. That petrol is in the tank and just your tank, and the task is a drain and a flush where your car sits. This is the one situation that can only truly occur at a forecourt, since anywhere else the car has been driven to get there.
Ignition on, or started for a second. With your system primed, the lines and filter already contain petrol that came from that tank. Drain, flush, see to the fuel filter: still normally straightforward.
The pump now spent a couple of miles on thinned fuel — that is what driving the car meant. Miles is only half of it; how hard it was driven matters equally. Either way this work runs to that tank, the lines, the fuel filter and clean fuel through the whole circuit. On the school run to the local primary school, the miles is short. Any mileage on the M8, under a mile from Deans, means the motor working hard throughout, and a run to Dunfermline, under 15 miles away, makes a very different task as well.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. What you are hearing is your engine signalling fuel that no longer acts like diesel. Whether it is the verge on Deans East Road, a lay-by or a side road, stop where you are then leave it. The drain and flush-through still go first, and they deal with it: if a vehicle is stopped quickly, permanent damage is very unusual.
Petrol in a diesel myths Deans motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. That guidance presumes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: a current diesel copes with a bit of petrol. If anything, the opposite. Finer parts and higher pressure are the way a newer diesel runs its fuel, and that makes the protection matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that catches more motorists than any other. Diesel in a petrol motor normally means a motor that won't run: the driver stops, and so does the harm. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, while the pump wears. Running isn't the same as fine.
An old fix for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." The petrol is still in that tank afterwards, and what it has diluted is not put back.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol lies in the filter and lines, ready to go right back through the pump on the next start. It is also genuinely risky to drain petrol into a can at the roadside.
Why petrol in a diesel occurs so easily
Nobody does it on purpose, and it's rarely carelessness. One way only, since of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol motor. That's how the forecourt makes it simple.
It takes place when routine and the vehicle stop matching. A new car, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. A forecourt you know, only with its pumps laid out differently. A train to catch, and a hurried fill en route to Livingston North. Years of petrol vehicles behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that's when. With rain, a call coming in, or a car full of children to deal with, the hand simply does what it has always done.
Next time you fill up in Deans: avoiding petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is just a clue.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: many vehicles print the fuel type there.
- Mark the key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Mistakes like this are easy to make while your mind is on something else, and so your phone goes away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- As soon as you notice, stop: less petrol inside the tank makes a thinner blend. What to do next doesn't change, though — still don't start the car.
Deans: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. If you're still on the forecourt — BP or anywhere else — ask the staff to help you roll the vehicle away from the pump. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it's run.
If it was AdBlue rather than petrol, say so. That's a different issue — corrosion and deposits rather than lost protection — and it has its own page for Deans.
One petrol in a diesel job around Deans costs more than another. Why?
The four situations above are four different jobs, so no single price for this would be honest. Chiefly, your cost moves with which situation you're in. The share matters next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for a van.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. Their answers are what change a range into one firm number.
About Deans, for a moment
Deans is a suburban area situated on the riverside in West Lothian, with a mix of terraced housing and local amenities. Deans has a population of around 5230 people and is located near several other communities, including Eliburn and Wester Dechmont. Deans sits at an elevation of 162 metres, overlooking the surrounding countryside. Deans is also within commuting distance of nearby cities, including Dunfermline, which is 12 miles away.
Deans and West Lothian: where our fuel drain cover runs
Eliburn, Wester Dechmont and Knightsridge are among the locations around Deans that the same teams work, answering petrol in diesel calls across Deans's EH postcode area. No need to bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
In Deans and still at the petrol pump?
Nothing beats it: that's where you now are. Turned off it remains; then ring.