Should You Worry? Petrol in a Diesel Car in Newmills
Likely less than you already are — provided no one has started the car. Petrol resting in a diesel tank does nothing to the engine until something pulls it through your fuel system — your ignition priming your pump, the starter, or driving itself. So the fair answer to the first question everyone around Newmills asks, "have I wrecked it?", is normally no. Petrol in Diesel is who to ring, with your engine left off, so it remains that way. The remainder of this page sets out 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.
The motor and petrol in a diesel: what happens
Diesel has two jobs on its way through a motor. It protects to begin with, and after that does it burn. What keeps the surfaces inside the high-pressure fuel pump and the injectors from wearing against each other is your diesel flowing through them — they are built to extremely fine clearances.
The second job petrol does not do at all, and the first it does badly. A pump running on a petrol blend is wearing itself out, because petrol is thinner than diesel and takes away the protection your fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where any clattering starts.
The shape of the problem is plain when you put those together. Not contact but circulation is what does the damage. All a tank with petrol in it amounts to is a fuel problem. Once the pump has been labouring on that petrol, a mechanical fault has started: anything shed by a pump that's wearing down is carried onward to your injectors with the fuel.
Newmills, petrol in a diesel: four situations, from mild to major
The best case there can be: filled up, not once started. Only the tank has petrol in it, and so the job is emptying that tank and purging your system where your car stands. This situation can only really occur on a forecourt: anywhere else, the car got there by being driven.
Your ignition switched on, or a short start. Once primed, the system has pulled petrol from your tank as far as the fuel filter and your lines. That's usually still a simple job — a drain, a flush, and the filter seen to.
Those few miles driven meant the pump working on fuel thinned by petrol throughout. Miles is only half of it; how hard it was driven matters equally. Either way the work includes that tank, your lines, your filter and clean fuel through the entire circuit. Driving the kids to the local primary school is one sort of trip. Very different once more: a trip to Armagh, under 15 miles away, or any mileage on the M77, over 50 miles from Newmills, where your engine never stopped labouring hard.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. What you are hearing is the engine signalling fuel that no longer runs like diesel. Stop where you are — on the verge on Chalet Road, at the kerb, down a side road — and do not move it again. Permanent damage is very rare when a car is stopped early, and the drain and flush-through that still come first take care of it.
What Newmills motorists get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — your tank just carries more of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that advice assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. A newer diesel runs its fuel through finer parts at higher pressure, which makes the lubrication matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up most motorists than any other. Feed diesel to a petrol motor and it usually won't run, and so the driver stops — and the harm stops with them. While your pump wears, a diesel fed petrol normally starts, ticks over and drives away as if nothing has happened. A running engine does not mean fine.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, meant for another fault. None of what petrol weakened gets put back by it — and later, the tank still holds the petrol.
The next start draws petrol back round the pump from your lines and your filter, where some of that ends up after the engine has run. That is why draining your tank yourself does not leave you sorted — a myth. Draining petrol into a can by the roadside is also genuinely hazardous.
How does petrol in a diesel occur?
A careless moment is seldom the cause, and nobody means to do it. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol car at all. The forecourt makes it simple, and the mistake runs one way.
Routine and your car getting out of step is when it happens. A car that is new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. A forecourt you know, only with its pumps arranged differently. Fuelling up in a hurry on the way to the nearest station, with a train to catch. The first fill-up in a diesel Volkswagen Tiguan after years of driving petrol is precisely the moment it occurs. With rain, a call arriving, or a car full of children to deal with, your hand just does what it has always done.
Next time you fill up in Newmills: preventing petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is only a hint.
- Many cars state the fuel type inside the filler flap or on the cap, so check it on your first fill in a vehicle you do not know.
- One of each in the house? Mark your key to the diesel — a coloured fob, a sticker — because intending to remember is not enough.
- Before the nozzle leaves the pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, yes, yet it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the petrol pump.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- Stop as soon as you notice. Less petrol inside your tank makes a weaker mixture. It doesn't change what to do next, which is still not to fire it up.
Already put petrol in a diesel in Newmills?
The order of things is brief, then. Don't turn your ignition on, and do not crank it. 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. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it's been run.
If it was AdBlue rather than petrol, say so. That's a different problem — corrosion and deposits instead of lost lubrication — and it has its own page for Newmills.
One petrol in a diesel task around Newmills costs more than another. Why?
The four scenarios above are four different jobs, so no single quote for this would be fair. Mostly, your cost shifts with which situation you're in. The proportion counts next, meaning how much of your tank is petrol, and then the location of your car and whether getting to it is safe for a van.
What went in, how much, and if it's run — three queries our technicians ask before costing, not after, for precisely that reason. Those answers turn a range into a straight figure.
About Newmills
Newmills is a small locality in County Tyrone, situated inland at an elevation of around 70 metres. Newmills lies near the settlements of Brackaville, Coalisland, and Donaghey, and is approximately 14 miles from the city of Armagh. Newmills is characterized by its predominantly semi-detached housing stock, reflecting its development as a residential area. Newmills is located about 345 miles northwest of London, in the heart of Northern Ireland.
Newmills and County Tyrone: where our fuel drain cover reaches
Brackaville, Coalisland and Donaghey are among the places near Newmills that the same teams work, answering petrol in diesel call-outs across Newmills's BT postcode area. Our technicians drain where the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump around Newmills?
Then you are in the best spot there is. Turned off it remains; then phone.