How Worried Should You Be? Petrol in a Diesel Car in Cripplegate
Provided it has not been started, you can worry less than you likely are. "Have I ruined it?" is the first thing everyone around Cripplegate asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing till it's dragged through the fuel system — by ignition priming, by your starter, or by being driven. Keep it that way: leave your engine off and call Petrol in Diesel. The remainder of this page explains what petrol actually does to a diesel, how to tell 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 the engine
Two tasks fall to diesel on its journey through a motor. It burns, and before it burns it lubricates. Very fine clearances are built into your injectors and the high-pressure fuel pump, and just the diesel flowing through stops their surfaces grinding together.
Poorly at the first, not at all at the second: that's petrol. It is thinner than diesel and strips away the protection the system hinges on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the problem is clear once you put those together. The damage is done by circulation, not by contact. Any tank with petrol in it is a fuel problem. After the pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that is grinding is carried downstream to the injectors with the fuel.
Cripplegate, petrol in a diesel: four situations, from mild to significant
Filled but never started — as good as it gets. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol kept in your tank alone, it is drained and flushed right where it stands, and nothing more is needed.
A brief spell of running, or merely the ignition on. Petrol has left your tank and reached your filter and the fuel lines, because the fuel system has been primed. That is generally still a simple job — a drain, a flush, and the fuel filter seen to.
Some miles driven, and the pump has spent every one of them working on weakened fuel. Tank, lines, filter, then clean fuel put through the whole circuit: that's the work, and the way your car was driven matters as much as the miles. Driving the children to St Leonard's Church of England Primary School is one kind of trip. A run as far as Southend-on-Sea, under 15 miles away, is a very different job. So is any mileage on the M2, under 25 miles from Cripplegate, where your engine has been running hard throughout.
Driven on till it complained — rattling, smoke, a ragged idle, a soft throttle. The fuel is not behaving like diesel any more, and your motor is telling you. Stop wherever you are — the verge on Tillingham Road, a lay-by, a side street — and leave it there. A car stopped soon very rarely has permanent damage, because the drain and the flush, which still come first, sort it out.
Cripplegate people and the petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up takes out nothing; it gives you a bigger tank of the same mix. That guidance supposes a diesel fuel system tolerates petrol by percentage. It does not.
If anything, the reverse is true. Myth: "A newer diesel can cope with a bit of petrol." A current diesel runs its fuel through finer parts at higher pressure, which makes the protection matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches motorists. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the damage. Whilst the pump wears, a diesel fed petrol normally starts, idles and drives away as though nothing has happened. Being able to run is not the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct problem. None of what petrol diluted gets put back by it — and afterwards, the tank still holds that petrol.
If your engine has run, part of that petrol sits in the filter and the fuel lines, not that tank — and the next start pulls it right back through your pump. So the myth "drain the tank yourself and you are sorted" doesn't hold. Also, a can of petrol drained by the kerbside is truly hazardous.
Why petrol in a diesel happens so easily
Carelessness is seldom the cause, and no one means to do it. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it easy.
When routine and the car stop matching, it occurs. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. A rushed fill en route to Southminster with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: precisely when it happens. With rain, a call arriving, or children to deal with, your hand just does what it has always done.
Next time you fill up around Cripplegate: preventing petrol in a diesel
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what counts.
- The first fill in a new motor is the time to check the filler flap — inside it, or on the cap, many vehicles state the fuel to use.
- One of each in the household? Label the key to the diesel — a bright fob, a sticker — because intending to remember isn't enough.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new vehicle, say "diesel" out loud. Silly, perhaps, yet it does the trick.
- Mistakes like this are easy to make while your mind is on something else, and so your phone goes away.
- Some diesels come with a filler built to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- The moment you notice, stop: less petrol in your tank makes a thinner mix. What to do next doesn't change, though — still don't fire it up.
Already put petrol in a diesel around Cripplegate?
Then the order of things is short. Do not fire it up, and don't turn the ignition on. If you are still on the forecourt — Woodfords Garage or anywhere else — ask the attendants to help you roll it away from the petrol pump. What went in, about how much, and if it has run: tell us those when you ring 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a different problem, with its own page for Cripplegate, because AdBlue brings corrosion and deposits rather than lost protection.
One petrol in a diesel task in Cripplegate costs more than another. Why?
There is no honest single price for this, because the four scenarios above are four separate tasks. The scenario itself does most of the work of moving the cost. Two things come after that: the petrol that got in as a proportion of what your tank holds, then the spot the vehicle is in and whether a technician can reach it safely.
Three questions come first, before any quote, rather than after — what was put in, how much, has it run — and that is the reason. Their replies are what change a range into one firm number.
About Cripplegate, for a moment
Cripplegate is a suburban area in Essex, situated inland at an elevation of around 25 metres, approximately 42.8 miles from London. Cripplegate is characterized by its semi-detached housing stock and is located near other communities such as Northend and Southminster. Cripplegate sits within commuting distance of Southend-on-Sea, which is about 10.2 miles away. Cripplegate has a population of around 1914 residents.
Fuel drain cover across Essex, Cripplegate included
Cripplegate waits in the CM postcode area, and the teams that answer petrol in diesel calls there work the locations near it as well — Northend, Southminster and Asheldham among them. Our engineers drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump around Cripplegate, right now?
The best position there is, then — that's where you are. Keep it turned off, then ring.