Stirchley: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — provided nobody has started the vehicle. Petrol sitting in a diesel tank does nothing to the engine until something draws it through the fuel system — your ignition priming your pump, the starter, or the drive itself. So the truthful answer to the first query everyone around Stirchley asks, "have I wrecked it?", is generally no. Keep it that way: leave the engine off and 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 doesn't happen to you a second time.
What petrol in a diesel does to your engine
Passing through a motor, diesel does two things at once. Before it burns, it protects — then it burns. Your high-pressure pump and the fuel injectors are built to extremely fine clearances, and your diesel passing through them is what keeps those surfaces from wearing against one another.
Petrol does the first job poorly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, leaving a pump running on that mixture to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Put those together and the shape of the issue is clear. Contact doesn't do the harm — movement does. Petrol in the tank is a fuel issue. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to your injectors beyond it.
Stirchley, petrol in a diesel: four cases, from mild to serious
Filled but not once started — as good as it gets. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With that petrol held in that tank alone, it is cleared and flushed right where it stands, and nothing more is needed.
Ignition on, or started for a moment. With the fuel system primed, your lines and filter now contain petrol that came from the tank. Drain, flush, see to your filter: still normally straightforward.
A few miles driven, and the pump has spent each of them working on thinned fuel. The work is your tank, your lines, your filter and fresh fuel through the whole circuit, and how hard the car was driven counts as much as how far. Short trips, such as the school run to Grange Park Primary School, are one thing. Driving as far as Wolverhampton, under 15 miles away, makes a very different task — as does any mileage on the M54, under 3 miles from Stirchley, with your engine labouring hard the whole time.
Driven on till it complained — clattering, smoke, a lumpy idle, a soft throttle. What you are hearing is the motor reporting fuel that no longer acts like diesel. Pull up on the spot — on the verge on Brookside Avenue, at the kerb, down a side road — and do not move it again. Long-term damage is very unusual when a car is pulled over soon, and the fuel drain and flush that still go first sort it out.
Petrol in a diesel myths Stirchley motorists hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. That guidance supposes a diesel fuel system handles petrol by percentage. It doesn't.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. Finer parts and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there is no harm done." The motorist of a petrol motor fed diesel normally has no choice but to stop, because it will not run, and the damage stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Running is not the same as fine.
An old fix for a separate problem lies behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol diluted gets put back by it — and later, your tank still contains the petrol.
If the motor has been run, part of the petrol sits in your filter and your lines, not that tank — and the next start pulls it straight back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. And, a can of petrol drained at the roadside is genuinely hazardous.
How it happens: petrol in a diesel
No one does it on purpose, and it is rarely carelessness. One way only, because of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol car. That is how the forecourt makes it easy.
The moment routine stops matching the car is the moment it happens. Any car 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 drive. Your ordinary forecourt, its pumps suddenly in a different order. Racing for a train at Telford Central and filling up en route. Years of petrol motors behind you, a diesel Skoda Octavia in front of you on the forecourt for its first tank — that is when. With rain, a call arriving, or children to deal with, the hand simply does what it has always done.
Next time you fill up around Stirchley: preventing petrol in a diesel
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on each forecourt. The label is what matters.
- Inspect the filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on your first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, in a home with one of each.
- It sounds silly 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.
- While you are thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- Less petrol makes a weaker mixture, and so stop the moment you notice — while remembering that your next step is unchanged. It's still not to fire it up.
Petrol already in a diesel around Stirchley? Begin here
Short and simple, then, is the order of things. Do not turn your ignition on, and don't fire it up. The staff at the forecourt — whether at Shell itself or wherever you filled up — will usually help roll it clear of the pump if you ask. What got in, roughly how much, and if it has run: tell us that when you ring 0333 366 0103.
Corrosion and deposits are the issue with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Stirchley page.
One petrol in a diesel task in Stirchley costs more than another. Why?
There's no fair single quote for this, because the four situations above are four different jobs. What moves your cost is chiefly which of them you're in. The share matters next, meaning how much of the tank is petrol, and then the location of the car and whether getting to it is safe for a technician.
That is why we ask three queries before pricing rather than after: what got in, how much, and if it has run. Given the replies, there is a straight figure rather than a range.
About Stirchley, for a moment
Stirchley is a suburban area in Shropshire, situated inland at an elevation of 119 metres, with a mix of terraced housing and local amenities. Stirchley lies approximately 13.7 miles from Wolverhampton and 126 miles from London, placing it within the wider West Midlands region. Stirchley is surrounded by nearby places such as Brookside, Town Park, and Tweedale, and has a population of around 5757 residents. Stirchley's setting is characterized by its location in a generally low-lying area of Shropshire, close to the outskirts of Telford,
Stirchley and Shropshire: where our fuel drain cover runs
Petrol in diesel call-outs around Stirchley — part of the TF postcode area — go to teams that also cover the locations around it, Brookside, Town Park and Tweedale among them. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations where we work.
In Stirchley and still at the pump?
Nothing beats it: that is where you are. Switched off it stays; then call.