How Worried Should You Be? Petrol in a Diesel Car in Hill Head
Likely less than you already are — as long as nobody has started it. Petrol resting in a diesel tank does nothing to the engine until something pulls it through the system — your ignition priming the pump, your starter, or the drive on its own. So the honest answer to the first question anyone around Hill Head asks, "have I ruined it?", is generally no. To keep it that way, call Petrol in Diesel then leave your motor switched off. The remainder of this page explains what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two tasks. It combusts, and before it burns it lubricates. Very fine clearances go into your injectors and the high-pressure fuel pump, and only the diesel flowing through keeps those surfaces from grinding together.
Of those two jobs, petrol manages the first poorly and the second never. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on that mixture to wear itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the clattering.
Taken together, they make clear the shape the issue has. The damage is done by movement, not by contact. A tank with petrol in it is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem begins.
Hill Head, petrol in a diesel: four situations, from mild to serious
Fuelled but never started — the best it gets. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held inside the tank alone, it's drained and flushed on the spot, and nothing more is needed.
Ignition on, or started for a moment. With the system primed, the lines and filter already contain petrol that has come from that tank. That is usually still an easy task — a drain, a flush, and the fuel filter seen to.
A couple of miles driven, and the pump has spent every one of them working on diluted fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way the work includes the tank, the lines, the filter and fresh fuel through the whole circuit. The school run to Crofton Hammond Junior School is one thing. Any miles on the M27, under 5 miles from Hill Head, means your engine has worked hard throughout, and a run to Portsmouth, under 10 miles away, is a very different task too.
Driven on till it protested — rattling, smoke, a ragged idle, a dead throttle. The fuel isn't acting like diesel any more, and your engine is saying so. Stop wherever you are — the verge on Osborne View Road, a lay-by, a side street — and leave the vehicle there. What goes first is still the fuel drain and flush-through, and that sorts it out, with long-term damage very unusual when a vehicle is stopped soon.
Hill Head people and the petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed when you top up — that tank just holds more of the same blend. That guidance presumes a diesel fuel system tolerates petrol by percentage. It does not.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. Protection matters more on current diesels, not less, because their fuel passes through more precise components at higher pressure.
This is the one that fools people. Myth: "If it starts and drives, there is no harm done." The motorist of a petrol engine fed diesel normally stops, since it will not run, and the damage stops there. Feed petrol to a diesel and it normally starts, idles and drives away as if nothing has happened — all while its pump is wearing. Fine and running aren't 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. It does not put back what petrol has thinned, and the petrol is still in the tank afterwards.
The next start sends petrol back round your pump out of your lines and the fuel filter, where some of that ends up after the motor has run. That's why draining the tank yourself does not leave you sorted — a myth. On top of that, petrol emptied into a can by the road is genuinely hazardous.
Petrol in a diesel: how does it happen?
On purpose? Never. Through carelessness? Seldom, if ever. 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 will not fit a petrol motor. That is how the forecourt makes it straightforward.
The moment routine stops matching your car is the moment it takes place. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the drive of the same household. A familiar forecourt with the pumps in a different order. Fuelling up in a rush en route to Fareham, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. Throw in a back seat full of children, a phone call or rain, and habit wins.
Preventing petrol in a diesel next time you fill up around Hill Head
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- Plenty of motors state the fuel type inside your filler flap or on the cap, so check it on your first fill in any motor you do not know.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, for a household with one of each.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It sounds daft. It does the trick.
- Put your phone away. This is an easy mistake to make while you're thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to refuse a petrol nozzle, and aftermarket devices exist for the rest. Count it as a backstop, and keep reading the petrol pump.
- Stop the moment you realise. Less petrol in the tank makes a weaker blend. It doesn't change what to do next, which is still not to start it.
Hill Head: already put petrol in a diesel?
The order of things is short, then. Do not turn your ignition on, and do not start it. The attendants on the forecourt — whether at Asda itself or wherever you filled up — will usually help roll it away from the pump if you ask. Call 0333 366 0103 next, with three facts — the fuel, the approximate volume, and whether it's run.
Corrosion and deposits are the problem with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Hill Head page.
One petrol in a diesel job around Hill Head costs more than another. Why?
An honest single price does not exist here: four situations, four separate jobs. What moves the cost is chiefly which of them you are in. The share matters next, meaning how much of your tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a technician.
That is why we ask three queries before quoting instead of after: what went in, how much, and whether it has run. A range becomes a straight figure once those replies are in.
About Hill Head itself
Hill Head is a small coastal village in Hampshire, situated near the cities of Portsmouth and Gosport. Hill Head has a low elevation of around 7 metres above sea level and is surrounded by other nearby places such as Stubbington and Meon. Hill Head is characterised by its predominantly detached housing stock, reflecting its status as a desirable residential location. Hill Head is also relatively close to London, being around 67.6 miles to the southwest of the capital.
Hill Head and Hampshire: where our fuel drain cover runs
Stubbington, Meon and Little Posbrook are among the places around Hill Head that the same teams work, answering petrol in diesel calls across Hill Head's PO postcode area. The car doesn't need to move to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Hill Head: still at the pump?
Then you're in the best spot there can be. Keep it off. Phone.