Coup Green: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it hasn't been started. Until your ignition primes your pump, the starter turns, or the car is driven, petrol in a diesel tank simply rests there and does no harm. Which means the honest reply to the first Coup Green question — "have I wrecked it?" — normally no. To keep the car that way, call Petrol in Diesel and leave the engine switched off. Below, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you again.
What petrol in a diesel does to the motor
Diesel does two jobs on its way through an engine. It lubricates to begin with, and only then does it burn. Extremely fine gaps go into the injectors and your high-pressure pump, and just the diesel running through keeps their surfaces from grinding together.
Petrol does the first job poorly and the second not at all. It is thinner than diesel and takes away the lubrication your fuel system depends on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
Combined, those make the shape of the problem clear. It's circulation that causes the damage, not contact. Petrol in a tank is a fuel fault. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors further along, which is why a pump that has worked on the petrol is where a mechanical problem starts.
Petrol in a diesel around Coup Green: how serious is it? Four situations
Fuelled up, never started. The best case there is. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With the petrol held in your tank alone, it's emptied and purged on the spot, and nothing more is needed.
A brief spell of running, or merely your ignition on. Once primed, the system has pulled petrol from your tank up to the fuel filter and your lines. That's normally still an easy task — a drain, a flush, and your filter seen to.
The pump now worked a few miles on weakened fuel — that is what driving the vehicle does. Miles is only half of that; how hard it was driven counts just as much. Either way the work includes the tank, the fuel lines, the filter and fresh fuel through the entire circuit. Driving the kids to Coupe Green Primary School is one kind of trip. A run as far as Preston, under 5 miles away, is a very different task. So is any mileage on the Preston Bypass, under 3 miles from Coup Green, where your engine has been working hard throughout.
Driven on till it protested — clattering, smoke, a ragged idle, a dead throttle. What you are hearing is your engine signalling fuel that no longer runs like diesel. Pull up where you are — on the verge on Methuen Avenue, at the kerb, down a side road — and do not move it. The fuel drain and flush-through still come first, and they deal with it: when a vehicle is pulled over soon, permanent damage is very rare.
Coup Green motorists 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." Nothing is removed by topping up — you are left with a bigger tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance assumes.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. Lubrication counts more on newer diesels, not less, since their fuel passes through smaller components at higher pressure.
This is the one that catches motorists. Myth: "If it starts and drives, there is no harm done." Diesel in a petrol motor normally leaves a motor that will not run: the motorist stops, and so does the damage. Whilst the pump wears, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Running is not the same as fine.
Myth: a two-stroke additive lets you to drive home. It was an old fix, supposed for another issue. None of what petrol diluted is put back by it — and later, that tank still contains the petrol.
Once the motor has run, part of the petrol is in the fuel filter and your lines, not that tank — and the next start pulls it right back through the pump. So the myth "drain the tank yourself and you're sorted" does not hold. On top of that, petrol emptied into a can by the road is genuinely risky.
How does petrol in a diesel occur?
No one does it on purpose, and it is rarely carelessness. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol car at all. So the error runs one way.
Habit and the vehicle falling out of step is when it takes place. Courtesy car, hire car, or a motor that's new. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps now in a different order. Rushing for a train at Bamber Bridge and fuelling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a driver accustomed to petrol: precisely when it occurs. Your hand does what it has always done once you add rain, a phone call or a back seat full of children.
Next time you fill up around Coup Green: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- Check the filler flap. Many cars state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, for a home with one of each.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Spotting it halfway? Stop at once. A thinner mixture results from less petrol in the tank, but the next stage remains the same: don't start it.
Put petrol in a diesel in Coup Green already?
Short and simple, then, is the order of things. Do not start it, and do not switch the ignition on. Ask the attendants to help you push it clear of the pump if you're still on the forecourt, whether that is Texaco or somewhere else. What was put in, about how much, and whether it has run: tell us that when you call 0333 366 0103.
Corrosion and deposits are the problem with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Coup Green page.
What makes one Coup Green petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four situations, four separate jobs. What moves the cost is mostly which of them you are in. The ratio matters next, meaning how much of that tank is petrol, followed by the position of your car and whether reaching it is safe for a technician.
Before any quote, not after, we ask three questions: your fuel that was put in, its volume, and if it has run. That is why. Their answers are what change a range into one firm number.
About Coup Green and where it is
Coup Green is a locality situated on the riverside in Lancashire, with an elevation of around 45 metres. Coup Green lies approximately 3.6 miles from Preston and is part of the wider North West region. Coup Green is characterised by its predominantly detached housing stock and is close to nearby places such as Coupe Green and Gregson Lane.
Across Lancashire and in Coup Green: fuel drain cover
Coup Green waits in the PR postcode area, and the teams that answer petrol in diesel jobs there work the places around it as well — Coupe Green, Gregson Lane and Roach Bridge among them. The car does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Still at the petrol pump around Coup Green?
Nothing beats it: that is where you now are. Keep it off. Phone.