Petrol in a Diesel Car in Mile Town: How Worried Should You Be?
Less than you likely are, provided it has not been started. Everyone around Mile Town starts with "have I ruined it?", and the fair answer is normally no: petrol resting inside that tank of a diesel remains harmless till priming, cranking or driving pulls it into the system. Keep it like that: leave the engine off then ring Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it's gone, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel has two jobs. It burns, and before it ignites it lubricates. Extremely fine tolerances are built into the fuel injectors and the high-pressure fuel pump, and just the diesel flowing through stops those surfaces grinding together.
Poorly at the first, not at all at the second: that's petrol. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication the system hinges on, and any pump working on that blend is wearing itself.
Put these together and the shape of the trouble is plain. Contact doesn't do the damage — movement does. A tank with petrol in it is a fuel fault. Whatever a worn pump sheds travels on, borne by the fuel, into your injectors further along, which is why a pump that has been working on that petrol is where a mechanical fault begins.
Four scenarios our technicians see around Mile Town: how bad is petrol in a diesel?
Fuelled but not once started — as good as it gets. Just your tank has petrol in it, so the task is clearing that tank and cleaning the system where your car stands. This situation can only truly occur on a forecourt: anywhere else, the vehicle got there by being driven.
Ignition on, or started for a moment. Once primed, your system has pulled petrol out of the tank as far as the fuel filter and your lines. That's normally still a straightforward job — a drain, a flush, and the fuel filter seen to.
A few miles driven, and your pump has spent every one of them labouring on diluted fuel. The work is that tank, your lines, the fuel filter and clean fuel through the whole system, and how hard the vehicle was driven counts as much as how far. Short trips, like the school run to Rose Street Primary School, are one thing. Very different a second time: a run to Southend-on-Sea, under 10 miles away, or any mileage on the M2, under 10 miles from Mile Town, where the motor never stopped working hard.
Driven on till it protested — rattling, smoke, a ragged idle, a soft throttle. The engine is telling you your fuel is no longer behaving like diesel. Stop wherever you are — the verge on Botany Close, a lay-by, a side street — then leave the car there. The fuel drain and flush-through still go first, and they deal with it: if a car is stopped early, long-term damage is very rare.
Petrol in a diesel stories Mile Town people hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — the tank simply holds more of the same blend. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance presumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the reverse. More precise parts and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools motorists. Diesel in a petrol motor generally means a motor that won't run: the motorist stops, and so does the harm. While your pump grinds, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate issue. That petrol is still inside the tank afterwards, and what it has diluted is not put back.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in the filter and lines, ready to go right back through the pump on the next start. And, a can of petrol drained at the kerbside is truly hazardous.
Why petrol in a diesel takes place at all
A careless moment is seldom the cause, and nobody means to do it. A diesel nozzle generally will not fit a petrol car, but the slimmer petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and only in one direction.
It happens when routine and your car stop matching. Courtesy car, hire car, or a car that's brand new. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps suddenly in a different order. Fuelling up in a hurry en route to Sheerness-On-Sea, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it occurs. Add rain, a phone call or a back seat full of children, and the hand does what it has always done.
Mile Town drivers: how to avoid petrol in a diesel next time
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- In a car you do not know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel type there.
- One of each in the home? Label your key to the diesel — a bright fob, a sticker — since intending to remember is not enough.
- "Diesel", aloud, before you lift the nozzle — every time a new or hired car gets its first tank. It seems silly. It does the trick.
- Mistakes like this are simple to make whilst your mind is on something else, so the phone goes away.
- Add-on devices are available for motors without one, and some diesels are built with a filler that will not accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Spotting it halfway? Stop at once. A weaker mix follows from less petrol in the tank, but the next step stays the same: don't start it.
Mile Town: already put petrol in a diesel?
Then the order of things is brief. Do not switch the ignition on, and do not start it. Ask the staff to help you push it clear of the petrol pump if you are still on the forecourt, whether that is Tesco or anywhere else. Then ring 0333 366 0103 and tell us what got in, roughly how much, and whether it's run.
Say so if it was AdBlue rather than petrol: it's a different problem, with its own page for Mile Town, since AdBlue brings corrosion and deposits instead of lost lubrication.
Why one petrol in a diesel job in Mile Town costs more than another
Four different tasks lie behind the four situations above — which is why there's no honest single price. What moves the cost is mostly which of them you're in. Next it is the ratio — how much petrol got in against how much your tank holds — and then where the vehicle is and whether a van can reach it safely.
That's why our technicians ask three queries before costing rather than after: what went in, how much, and whether it has run. With the answers, there is a straight figure rather than a range.
About Mile Town
Mile Town is a coastal suburban area in Kent, situated near the mouth of the Thames estuary at a low elevation of around 2 metres. Mile Town lies within commuting distance of London, approximately 38.6 miles to the west, and is close to the nearby city of Southend-on-Sea. Mile Town is characterised by its predominantly terraced housing stock, reflecting its development as a residential area.
Mile Town and Kent: where our fuel drain cover runs
Sheerness, Marine Town and West Minster are among the places around Mile Town that the same vans work, answering petrol in diesel jobs across Mile Town's ME postcode area. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain.
In Mile Town and still at the pump?
Nothing beats it: that is where you are. Turned off it remains; then phone.