Woodchurch: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, provided it hasn't been started. "Have I ruined it?" is the first question anyone around Woodchurch asks, and the honest answer is generally no, since petrol resting in a diesel tank harms nothing until it's drawn through your fuel system — by ignition priming, by the starter, or by being driven. To leave the car that way, ring Petrol in Diesel and leave the motor switched off. What petrol really does to a diesel, how to judge how far it has gone, and how to keep it from happening a second time: that is the remainder of this page.
Petrol in a diesel: what does it do to the motor?
On its way through an engine, diesel has two jobs. It ignites, and before it burns it protects. Designed to extremely fine tolerances, the injectors and the pump rely on your diesel moving through them to stop their surfaces wearing against one another.
Badly at the first, not at all at the second: that's petrol. It's runnier than diesel and strips away the protection the fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the rattling comes from.
Seen together, they make clear the shape the problem takes. It's movement that causes the harm, not contact. Petrol in the tank is a fuel fault. After your pump has been working on that petrol, a mechanical problem has started: whatever is shed by a pump that is wearing travels onward to your injectors with your fuel.
Woodchurch, petrol in a diesel: four cases, from mild to significant
Filled up, not once started. The best case there can be. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held inside the tank alone, it's cleared and cleaned on the spot, and nothing more is needed.
Ignition on, or started for a second. With the fuel system primed, your lines and filter already contain petrol that has come from your tank. Still normally simple: drain, flush, and your filter dealt with.
Your pump now worked a couple of miles on diluted fuel — that is what driving the vehicle does. Tank, lines, filter, then fresh fuel put through the whole system: that's the work, and the way the car was driven matters as much as the distance. Short trips, such as the school run to Fender Primary School, are one thing. Any mileage on the M53, under a mile from Woodchurch, means the engine working hard throughout, and a run to Liverpool, under 5 miles away, makes a very different task as well.
Clattering, a ragged idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is the engine reporting fuel that no longer runs like diesel. Stop where you are — on the verge on Ferny Brow Road, at the kerb, down a side road — and don't move it. The fuel drain and flush still go first, and they sort it out: when a vehicle is pulled over early, lasting damage is very rare.
Woodchurch drivers and the petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a bigger tank of the same mix. That advice supposes a diesel fuel system handles petrol by percentage. It does not.
Myth: a current diesel copes with a bit of petrol. If anything, the reverse. Smaller parts and higher pressure are how a newer diesel runs its fuel, and that makes the protection count more, not less.
This is the one that fools people. Myth: "If it starts and drives, there is no harm done." The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops with them. A diesel fed petrol generally starts, idles and drives away as if nothing has happened, while the pump grinds. Running isn't the same as fine.
An outdated workaround for a separate problem lies behind this one. Myth: "Add some two-stroke oil and drive the car home." It doesn't put back what petrol has thinned, and that petrol is still in that tank later.
Myth: "Drain your tank yourself and you are sorted." Once the motor has run, some of that petrol is no longer in your tank: it's in the filter and the fuel lines, and it goes straight back through your pump at the next start. On top of that, petrol emptied into a can by the road is truly hazardous.
How it happens: petrol in a diesel
It's rarely carelessness, and nobody does it on purpose. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it easy, and the mistake runs one way.
It occurs when routine and your car stop matching. Hire cars, courtesy cars, and motors that are new to you. Two cars on one drive, one petrol, one diesel. A forecourt you know, but with its pumps laid out differently. A train to catch, and a hurried fill en route to Upton. A new-to-you diesel Volkswagen Passat, its first fuelling, and a driver used to petrol: precisely when it happens. With rain, a call coming in, or children to deal with, your hand just does what it has always done.
How to avoid petrol in a diesel at your next fill-up around Woodchurch
- The label is what counts, so check the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- Many vehicles state the fuel type inside your filler flap or on the cap, and so check it on the first fill in any car you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a home with one of each.
- Before the nozzle leaves the pump the first time you fill a hired or new vehicle, say "diesel" aloud. Daft, perhaps, yet it works.
- While you're thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels have a filler designed to block a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Stop as soon as you notice. Less petrol inside your tank makes a thinner mixture. It does not change what to do next, which is still not to crank it.
Petrol already in a diesel around Woodchurch? Begin here
Then, there's only a short order of things. Do not start the car, and do not turn the ignition on. Yet at the forecourt, at Asda or anywhere else? Ask the staff to help you push the car clear of the pump. Then phone 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Woodchurch, since AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel job around Woodchurch costs more than another
The four situations above are four separate tasks, so no single quote for this would be honest. The situation itself does most of the work of moving the cost. Next it is the ratio — how much petrol was put in against how much that tank takes — and after that where the vehicle is and whether our van can reach it safely.
That is why our technicians ask three queries before pricing rather than after: what was put in, how much, and if it's run. Those replies are what turn a range into one firm number.
About Woodchurch
Woodchurch is a suburban area on the Wirral Peninsula in Merseyside, situated near the coast at an elevation of around 17 metres. Woodchurch lies close to the cities of Liverpool and Birkenhead, with nearby places including Noctorum, Arrowe Hill, and Upton. Woodchurch has a mix of housing types, but is predominantly characterised by terraced homes. Woodchurch is located approximately 4.9 miles from Liverpool city centre, making it a commuter-friendly area.
Woodchurch and Merseyside: where our fuel drain cover reaches
The teams answering petrol in diesel call-outs around Woodchurch, in the CH postcode area, equally work the locations near it, Noctorum, Arrowe Hill and Upton among them. Our technicians drain where the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in Woodchurch, right now?
No position is better: that's where you now are. Ring, and keep it switched off.