Should You Worry? Petrol in a Diesel Car in Crowhill
Unstarted? Then less worried than you likely are. Petrol resting in a diesel tank does nothing to your engine till something pulls it through your fuel system — the ignition priming the pump, the starter, or driving itself. So the truthful answer to the first query everyone in Crowhill asks, "have I ruined it?", is usually no. Petrol in Diesel is who to ring, with the motor left off, and so it remains that way. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to your engine?
Passing through an engine, diesel does two things at the same time. Before it combusts, it protects — and then it burns. Extremely fine clearances go into your injectors and the high-pressure pump, and just the diesel running through keeps those surfaces from grinding together.
Petrol does the first task poorly and the second not at all. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication the fuel system hinges on, and any pump working on that mix is wearing itself.
Put these together and the shape of the trouble is clear. The damage is done by movement, not by contact. Petrol in the tank is a fuel problem. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors beyond it.
How bad is petrol in a diesel? Four situations we see in Crowhill
Filled but never started — the best it gets. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held inside that tank alone, it is cleared and purged on the spot, and nothing more is needed.
Started for a moment, or just the ignition on. With the fuel system primed, the fuel lines and filter already hold petrol that came from your tank. Still generally simple: drain, flush, and your filter seen to.
Your pump has worked a couple of miles on diluted fuel — that is what driving it does. The work is your tank, your lines, your filter and fresh fuel through the entire circuit, and how hard the vehicle was driven counts as much as how far. Short trips, like the school run to Holy Trinity CofE Primary School, are one thing. A run as far as Manchester, under 10 miles away, is a very different job. So is any miles on the M60, under a mile from Crowhill, where the engine has been working hard the whole time.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. The fuel isn't behaving like diesel any more, and your motor is saying so. Leave it wherever it stops: a lay-by, a quiet street, the verge on Crowhill Road. The fuel drain and flush still go first, and they sort it out: if a car is stopped quickly, long-term damage is very uncommon.
What Crowhill people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mix is all it gives, since topping up removes nothing. That guidance supposes a diesel fuel system handles petrol by percentage. It does not.
Not so: a newer diesel copes with a bit of petrol. Rather, the reverse. A current diesel sends its fuel through more precise components at higher pressure, which makes the lubrication count more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. Diesel in a petrol motor usually leaves a motor that will not run: the driver stops, and so does the damage. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump grinds. Running does not mean fine.
Myth: a two-stroke additive makes it safe to drive home. It was an old fix, meant for another problem. None of what petrol thinned gets put back by it — and afterwards, the tank still contains the petrol.
If your engine has run, part of the petrol is in the fuel filter and the lines, not your tank — and the next start pulls it right back through the pump. So the myth "drain the tank yourself and you are sorted" doesn't hold. It's also genuinely risky to drain petrol into a can by the roadside.
How does petrol in a diesel occur?
A careless moment is seldom the cause, and no one means to do it. One way only, since of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol motor. That's how the forecourt makes it straightforward.
The moment habit stops matching the vehicle is the moment it happens. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the drive of the same household. A forecourt you know, only with its pumps arranged differently. Fuelling up in a hurry en route to Ashton-Under-Lyne, with a train to catch. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Renault Clio for the first time. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
How to avoid petrol in a diesel at your next fill-up in Crowhill
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what matters.
- Many cars state the fuel type inside the filler flap or on the cap, and so check there on your first fill in a car you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key when a home has one of each. So mark it.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop reading the petrol pump.
- Stop as soon as you notice. Less petrol inside that tank means a thinner mix. It doesn't change what to do next, which is still not to fire it up.
Put petrol in a diesel around Crowhill already?
In that case, there is only a short order of things. Leave it unstarted, with your ignition off too. Still at the forecourt, at Sainsbury's or anywhere else? Ask the staff to help you roll the car away from the pump. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and whether it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Crowhill has a page just for it.
Why one petrol in a diesel job in Crowhill costs more than another
There's no fair single price for this, since the four scenarios above are four separate jobs. Which of them you are in is chiefly what shifts the cost. The share counts next, meaning how much of the tank is petrol, and then the location of your car and whether reaching it is safe for our van.
That is why our technicians ask three questions before costing instead of after: what was put in, how much, and if it has run. A range turns into a straight figure once those answers are in.
About Crowhill itself
Crowhill is a suburban area in Greater Manchester, situated approximately 5.7 miles from Manchester city centre. Crowhill sits at an elevation of 108 metres, with semi-detached housing being the predominant type of accommodation in the area. Crowhill is located inland, with nearby places including Waterloo and Ashton-under-Lyne, and is around 160.5 miles from London.
Fuel drain cover in Crowhill and across Greater Manchester
Crowhill waits in the OL postcode area, and the vans that answer petrol in diesel call-outs there work the spots near it as well — Waterloo, Taunton and Ashton-under-Lyne among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places we work, and the car doesn't need to come to us.
Still at the petrol pump around Crowhill?
In that case, you could not be in a better place. Leave the vehicle switched off, and ring.