Mawsley Village: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — as long as no one has started it. Everyone around Mawsley Village starts with "have I ruined it?", and the honest answer is generally no: petrol resting inside that tank of a diesel remains harmless till priming, cranking or driving draws it into the fuel system. Keep it that way: leave your motor off then call Petrol in Diesel. The rest of this page explains what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Inside the motor: what petrol in a diesel does
Diesel has two jobs on its way through a motor. Oiling comes before burning; it does both. Designed to very fine tolerances, the injectors and the pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
The second job petrol does not do at all, and the first it does badly. It's runnier than diesel and strips away the lubrication the system hinges on, and so a pump running on a petrol mix 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's where the knocking comes from.
Put those together and the shape of the trouble is plain. It is circulation that causes the harm, not contact. All a tank with petrol in it amounts to is a fuel issue. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to your injectors beyond it.
Petrol in a diesel in Mawsley Village: how serious is it? Four cases
The best case there can be: filled up, not once started. Just that tank has petrol in it, so the task is emptying the tank and purging the system where the car stands. This situation can only really happen on a forecourt: anywhere else, the vehicle got there by being driven.
A brief spell of running, or just the ignition on. Once primed, the system has pulled petrol out of that tank as far as the filter and the fuel lines. Still normally simple: drain, flush, and your filter sorted.
Driven a few miles. Now the pump has spent those miles running on thinned fuel. The work is the tank, the lines, the fuel filter and clean fuel through the entire circuit, and how hard the car was driven counts as much as how far. Short trips, such as the school run to Mawsley Primary School, are one matter. A run as far as Leicester, under 25 miles away, is a very different task. So is any distance on the M1, under 15 miles from Mawsley Village, where the motor has been running hard the whole time.
Driven till it complained. Rattling, an uneven idle, smoke, a throttle that has gone soft. The fuel is not acting like diesel any more, and the engine is telling you. Leave it where it stops: a lay-by, a side street, the verge on Cransley Rise. A car pulled over early very seldom has long-term damage, since the drain and the flush-through, which still go first, take care of it.
Petrol in a diesel stories Mawsley Village motorists hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mix. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. At higher pressure, through smaller parts: that is how a modern diesel moves its fuel, and so the protection counts more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. Any petrol engine fed diesel generally won't run, so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump wears. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct issue. It doesn't put back what petrol has thinned, and the petrol is still inside the tank later.
The next start sends petrol back round the pump from your lines and your filter, where some of that sits once the engine has run. That is why draining the tank yourself doesn't leave you sorted — a myth. And, a can of petrol filled at the roadside is genuinely hazardous.
Why petrol in a diesel takes place at all
It is seldom carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it easy, and the slip runs one way.
Routine and the car falling out of step is how it happens. Any motor that is 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 ordinary forecourt, its pumps suddenly in a different order. Racing for a train at Kettering and fuelling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Add rain, a phone call or a back seat full of children, and the hand does what it has always done.
Preventing petrol in a diesel next time you fill up around Mawsley Village
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- Check the filler flap. Many cars state the fuel type inside the flap or on the cap. Look at it on the first fill in any motor you don't know.
- Label the 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 meaning to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. It seems silly and it works.
- Mistakes like this are straightforward to make whilst your mind is on something else, so your phone goes away.
- Add-on devices exist for cars without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Less petrol makes a weaker mix, so stop the moment you notice — though remembering that the next stage is unchanged. It is still not to crank it.
Already put petrol in a diesel in Mawsley Village?
The order of things is brief, then. Leave it unstarted, with your ignition switched off too. Ask the attendants to help you roll it away from the petrol pump if you're still on the forecourt, whether that is Shell or anywhere else. Then ring 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 is a separate issue, with its own page for Mawsley Village, because AdBlue brings corrosion and deposits rather than lost protection.
One petrol in a diesel job around Mawsley Village costs more than another. Why?
The four scenarios above are four different tasks, so no single price for this would be honest. Which of them you are in is mostly what moves your cost. Next it is the proportion — how much petrol was put in against how much your tank holds — and then where the car is and whether our van can reach it safely.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. Those replies are what turn a range into one firm number.
About Mawsley Village itself
Mawsley Village is a rural settlement in Northamptonshire, situated in the East Midlands region of England, with an elevation of around 135 metres. Mawsley Village lies approximately 22 miles from Leicester and 67 miles from London, placing it in a relatively central position. Mawsley Village is characterised by its predominantly detached housing stock and is surrounded by nearby places such as Great Cransley, Broughton, and Loddington. Mawsley Village has a population of around 1709 residents.
Fuel drain cover across Northamptonshire, Mawsley Village included
Great Cransley, Broughton and Loddington are among the locations around Mawsley Village that the same teams work, answering petrol in diesel calls across Mawsley Village's NN postcode area. Our technicians drain where your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the petrol pump around Mawsley Village, right now?
Nothing beats it: that is where you now are. Keep it off. Ring.