Petrol in a Diesel Car in Caldy: How Worried Should You Be?
Probably less than you are now — provided nobody has started it. "Have I ruined it?" is the first question everyone in Caldy asks, and the truthful answer is normally no, because petrol resting in a diesel tank hurts nothing till it is dragged through the system — by ignition priming, by your starter, or by driving. Petrol in Diesel is who to ring, with the engine kept off, and so it remains that way. Further down, you will find what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you again.
Your engine and petrol in a diesel: what goes on
On its way through an engine, diesel does two tasks. Before it burns, it lubricates — and then it combusts. What stops the surfaces inside the high-pressure pump and the fuel injectors from wearing against one another is the diesel passing through them — they are made to very fine gaps.
Of those two jobs, petrol handles the first badly and the second not at all. A pump working on a petrol mixture is wearing itself out, since petrol is thinner than diesel and strips out the lubrication your fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any clattering starts.
Together, those make the shape of the trouble clear. It's movement that does the harm, not contact. All a tank with petrol in it amounts to is a fuel problem. After the pump has been labouring on that petrol, a mechanical problem has begun: whatever is shed by a pump that's wearing is carried downstream to the injectors with the fuel.
Caldy, petrol in a diesel: four cases, from mild to significant
Filled up, not once started. The best case there is. The petrol is inside that tank and only your tank, and the task is a drain and a flush where the car stands. This is the one situation that can only truly happen on a forecourt, because anywhere else your car has been driven to get there.
Ignition on, or started for a second. With the system primed, the fuel lines and filter already hold petrol that has come from that tank. Usually nothing more than clearing, rinsing and seeing to the filter, so still straightforward.
The pump now spent a couple of miles on weakened fuel — that's what driving the car does. Distance is only half of it; how hard it was driven counts equally. Either way the work includes that tank, your lines, the fuel filter and clean fuel through the entire circuit. The school run to West Kirby St Bridget's CofE Primary School is one thing. Getting as far as Liverpool, under 10 miles away, makes a very different job — as does any miles on the Moreton Spur, under 5 miles from Caldy, with the motor labouring hard the whole time.
Driven on till it protested — knocking, smoke, a lumpy idle, a soft throttle. The motor is telling you your fuel is no longer acting like diesel. Stop on the spot — on the verge on Croft Drive, at the kerb, down a side road — and do not move it. A vehicle stopped soon very seldom has long-term damage, as the fuel drain and the flush-through, which still go first, deal with it.
Caldy motorists and the petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. Smaller parts and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there's no harm done." Feed diesel to a petrol engine and it normally will not run, and so the driver stops — and the harm stops with them. Feed petrol to a diesel and it usually fires up, ticks over and pulls away as if nothing happened — all while its pump is wearing. Fine and running are not the same thing.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate issue. That petrol is still inside your tank afterwards, and whatever it has weakened is not put back.
The next start sends petrol back round your pump from the lines and the fuel filter, where some of it ends up once your engine has been run. That's why draining the tank yourself does not leave you sorted — a myth. And, a can of petrol drained at the roadside is truly dangerous.
Why petrol in a diesel happens so easily
No one does it on purpose, and it is seldom carelessness. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle generally will not go into a petrol car at all. So the error runs one way.
It happens when routine and your car stop matching. A motor that's new to you — hired, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. Rushing for a train outside West Kirby and filling up en route. Exactly the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Throw in a back seat full of children, a phone call or rain, and habit wins.
Next time you fill up in Caldy: preventing petrol in a diesel
- Green for unleaded and black for diesel is usual in the UK — but not on each forecourt. Trust the label on the petrol pump, not the colour.
- Plenty of cars state the fuel type inside the filler flap or on the cap, and so check there on the first fill in any vehicle you do not know.
- Label the key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away and keep your mind on the petrol pump.
- Add-on devices exist for cars without one, and some diesels are built with a filler that will not take a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- The moment you realise, stop: less petrol inside the tank makes a weaker blend. What to do next doesn't change, though — still don't fire it up.
Put petrol in a diesel around Caldy already?
Short and simple, then, is the order of things. Starting it is out, and so is switching on your ignition. The staff on the forecourt — whether at Morrisons itself or wherever you filled up — will normally help roll it clear of the pump if you ask. What was put in, roughly how much, and whether it's run: tell us those when you ring 0333 366 0103.
Corrosion and deposits form the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Caldy page.
Why one petrol in a diesel task in Caldy costs more than another
There's no fair single price for this, since the four situations above are four different jobs. What shifts your cost is mostly which of them you're in. Two things come after that: the petrol that got in as a proportion of what that tank holds, then the place the car is in and whether a technician can reach it safely.
That's why our engineers ask three questions before costing instead of after: what was put in, how much, and if it's run. The replies turn a range into a straight figure.
About Caldy, briefly
Caldy is a small village on the Wirral Peninsula in Merseyside, situated near the coast at an elevation of around 43 metres. Caldy lies close to the nearby settlements of Grange, Newton, and West Kirby, and is approximately 8 miles from Liverpool. Caldy has a population of around 578 people, predominantly living in detached houses. Caldy is also relatively distant from London, at around 180 miles away.
Fuel drain cover around Caldy and across Merseyside
Grange, Newton and West Kirby are among the locations near Caldy that the same teams work, answering petrol in diesel calls across Caldy's CH postcode area. Our technicians drain wherever the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the pump around Caldy, still?
Then you're in the best place there can be. Call, and keep it switched off.