How Worried Should You Be? Petrol in a Diesel Car in Mostyn
Unstarted? Then less worried than you likely feel. Everyone in Mostyn starts with "have I wrecked it?", and the fair answer is normally no: petrol resting in the tank of a diesel stays harmless till priming, cranking or driving pulls it into the fuel system. To leave the vehicle like that, ring Petrol in Diesel then leave the motor alone. What petrol actually does to a diesel, how to judge how far it's gone, and how to stop it from happening again: that is the rest of this page.
Inside your engine: what petrol in a diesel really does
On its way through a motor, diesel does two jobs. It ignites, and before it combusts it lubricates. Extremely fine clearances go into the fuel injectors and the high-pressure fuel pump, and just the diesel running through stops those surfaces grinding together.
Badly at the first, not at all at the second: that is petrol. The clattering comes from petrol being designed not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the protection the fuel system depends on, and any pump working on such a blend is wearing itself.
Put those together and the shape of the trouble is clear. Contact doesn't do the damage — movement does. Any tank with petrol in it is a fuel fault. Once your pump has been working on that petrol, a mechanical problem has begun: whatever is shed by a pump that's grinding travels downstream to your injectors with your fuel.
Four situations we see around Mostyn: how serious is petrol in a diesel?
Filled up, and never started: nothing beats it. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in your tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
A brief spell of running, or merely your ignition on. With the system primed, the fuel lines and filter now hold petrol that came from the tank. Still usually easy: drain, flush, and your filter seen to.
Driven a few miles. Now the pump has spent these miles labouring on thinned fuel. Mileage is only half of it; how hard it was driven matters equally. Either way this work runs to your tank, your lines, your filter and fresh fuel through the entire system. The school run to the local primary school is one thing. Any mileage on the Moreton Spur, under 10 miles from Mostyn, means the engine has worked hard throughout, and a run to St Asaph, under 10 miles away, is a very different task too.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. What you are hearing is your engine signalling fuel that no longer acts like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Y Nant. Lasting damage is very rare when a vehicle is stopped quickly, and the drain and flush that still go first take care of it.
Stories Mostyn people hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed when you top up — the tank just carries more of the same blend. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance assumes.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. A modern diesel runs its fuel through smaller parts at higher pressure, which makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. Any petrol motor fed diesel normally won't run, so the driver stops and the damage stops with them. Feed petrol to a diesel and it generally starts, idles and drives away as if nothing happened — all the while its pump is wearing. Fine and running are not the same at all.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a different fault. It doesn't put back what petrol has thinned, and that petrol is still inside that tank later.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol lies in the filter and lines, ready to go right back through your pump at the next start. Emptying petrol into a can at the kerbside is also really hazardous.
How does petrol in a diesel take place?
Nobody does it on purpose, and it is seldom carelessness. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol vehicle. That's how the forecourt makes it easy.
It happens when habit and your car stop matching. Courtesy car, hire car, or a motor that's brand new. One petrol and one diesel on the drive of the same household. The pumps in a different order on a familiar forecourt. Rushing for a train outside West Kirby and fuelling up en route. A new-to-you diesel Volkswagen Passat, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
Preventing petrol in a diesel next time you fill up around Mostyn
- A green handle for unleaded and black for diesel is normal in the UK — but not on every forecourt. Trust the label on the petrol pump, not the colour.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of vehicles state the fuel there.
- Mark the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, yes, but it does the trick.
- Whilst you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available for the remainder. Count it as a backstop, and keep checking the petrol pump.
- Less petrol makes a weaker mix, and so stop the moment you realise — while remembering that the next stage is unchanged. It's still not to fire it up.
Petrol already in a diesel in Mostyn? Start here
Short and simple, then, is the order of things. Do not fire it up, and do not switch the ignition on. If you are still on the forecourt — Texaco or anywhere else — ask the staff to help you push it away from the petrol pump. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and if it's run.
Corrosion and deposits form the issue with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Mostyn page.
One petrol in a diesel job around Mostyn costs more than another. Why?
There is no honest single price for this, because the four situations above are four different jobs. The scenario itself does most of the work of moving the cost. Where the car is matters too, and whether a van can safely reach it, after the proportion of petrol to what your tank takes.
Three questions come first, before any quote, instead of after — what was put in, how much, has it run — and that is the reason. A range becomes a straight figure when the replies are in.
About Mostyn and its setting
Mostyn is a small coastal village in Flintshire, situated near the Irish Sea at an elevation of around 35 metres. Mostyn has a mix of housing types, but detached homes are the most common, and it is located near other small communities such as Rhewl-Mostyn and Glan-y-don. Mostyn is close to the city of St Asaph, which is about 8.5 miles away, and is part of a wider area of rural and coastal settlements in north Wales.
Fuel drain cover across Flintshire, Mostyn included
Our teams answering petrol in diesel calls around Mostyn, in the CH postcode area, equally work the spots near it, Rhewl-Mostyn, Maes Pennant and Glan-y-don included. 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.
In Mostyn and still at the pump?
Nothing beats it: that is where you now are. Keep it off. Ring.