Petrol in a Diesel Car in Lichfield: How Worried Should You Be?
Not started? Then less worried than you likely feel. "Have I ruined it?" is the first thing anyone in Lichfield asks, and the truthful answer is normally no, because petrol left in a diesel tank harms nothing till it is dragged through your fuel system — by ignition priming, by the starter, or by being driven. To keep the car that way, call Petrol in Diesel and leave the motor alone. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and the way to make sure you never do it again.
Inside the motor: what petrol in a diesel does
On its way through an engine, diesel has two tasks. It ignites, and before it combusts it lubricates. The high-pressure fuel pump and your injectors are designed to extremely fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
Petrol handles the first task badly and the second not at all. A pump working on a petrol mix is wearing itself out, since petrol is runnier than diesel and takes away the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where the knocking starts.
The shape of the trouble is clear when you put those together. The damage is done by circulation, not by contact. Where the petrol is only inside the tank, it's a problem of fuel, nothing more. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with your fuel to the injectors beyond it.
How bad is petrol in a diesel? Four scenarios we see in Lichfield
Fuelled up, never started. The best case there is. That petrol is inside that tank and only your tank, and the job is a drain and a flush where the car stands. This is the one scenario that can only truly occur on a forecourt, since anywhere else your car has been driven to get there.
Ignition on, or started for a second. Once primed, your system has pulled petrol from the tank as far as the fuel filter and your lines. Usually little more than draining, rinsing and seeing to the fuel filter, and so still simple.
Driven a few miles. Now the pump has spent those miles running on thinned fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way the work runs to the tank, the lines, the fuel filter and fresh fuel through the whole system. Short trips, such as the school run to St Michael's CofE (C) Primary School, are one thing. Driving as far as Wolverhampton, under 15 miles away, makes a very different task — as does any miles on the M6 Toll, under 3 miles from Lichfield, with your engine labouring hard all the way.
Driven on till it complained — clattering, smoke, a ragged idle, a soft throttle. The engine is telling you your fuel is no longer acting like diesel. Leave it where it has stopped: a lay-by, a side street, the verge on Breadmarket Street. The drain and flush still come first, and they deal with it: when a car is stopped quickly, long-term damage is very rare.
What Lichfield people get told about petrol in a diesel — and the myths in it
False: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a fuller tank of the same mixture. That guidance assumes a diesel fuel system handles petrol by percentage. It does not.
"Current diesels can handle a little petrol" — a myth, and closer to the opposite. Finer components and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
This is the one that catches motorists. Myth: "If it starts and drives, there is no harm done." Feed diesel to a petrol motor and it normally will not run, and so the motorist stops — and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump grinds. Running isn't the same as fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another fault. None of what petrol diluted gets put back by it — and afterwards, that tank still contains the petrol.
Myth: "Drain the tank yourself and you're sorted." After the motor has been run, some of the petrol is no longer inside that tank: it's in the filter and your lines, and it goes right back through your pump at the next start. It is also genuinely risky to drain petrol into a can by the kerbside.
How it happens: petrol in a diesel
Nobody does it on purpose, and it's seldom carelessness. One way only, since 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's how the forecourt makes it straightforward.
Habit and the vehicle falling out of step is how it occurs. Hire cars, courtesy cars, and cars that are new to you. Two motors on one drive, one petrol, one diesel. A forecourt you know, only with its pumps laid out differently. Racing for a train outside Lichfield City and fuelling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
Preventing petrol in a diesel next time you fill up in Lichfield
- Green for unleaded and black for diesel is normal in the UK — but not on every forecourt. Go by the label on the pump, not the colour.
- Inspect your filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on your first fill in a motor you don't know.
- One of each in the household? Mark your key to the diesel — a bright fob, a sticker — since intending to remember isn't enough.
- It sounds daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in that tank makes a weaker blend. What to do next does not change, though — still don't start it.
Petrol already in a diesel around Lichfield? Start here
Short and simple, then, is the order of things. Starting it is out, and so is turning on your ignition. The attendants on the forecourt — whether at Tesco itself or wherever you filled up — will normally help roll it clear of the petrol pump if you ask. What went in, roughly how much, and if it has run: tell us that when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a different problem — corrosion and deposits and not lost protection — and it has its own page for Lichfield.
What makes one Lichfield petrol in a diesel task cost more than the next
A fair single price doesn't exist here: four scenarios, four separate tasks. The situation itself does most of the work of moving the cost. Where the vehicle is matters too, and whether our van can safely get to it, after the share of petrol to what that tank holds.
What was put in, how much, and if it has run — three queries we ask before quoting, not after, for precisely that reason. A range turns into a straight figure when those answers are in.
About Lichfield
Lichfield is a city located in the county of Staffordshire, situated beside a series of lakes and pools, at an elevation of around 87 metres. Lichfield sits in the heart of the West Midlands region, approximately 108 miles northwest of London, and is close to nearby places such as Christ Church and Stowe. Lichfield is characterised by its predominantly detached housing stock and is a short distance from the city of Wolverhampton. Lichfield has a population of around 34,928 people.
Across Staffordshire and in Lichfield: fuel drain cover
Christ Church, Stowe and Sandfields are among the locations near Lichfield that the same vans work, answering petrol in diesel calls across Lichfield's WS postcode area. Our technicians drain where your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump in Lichfield, still?
Nothing beats it: that is where you are. Call, and leave it turned off.