How Worried Should You Be? Petrol in a Diesel Car in Greenside
Unstarted? Then less anxious than you probably are. "Have I ruined it?" is the first thing anyone around Greenside asks, and the truthful answer is usually no, since petrol resting in a diesel tank hurts nothing until it is drawn through the system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to ring, with your motor kept off, so it stays that way. Further down, this page sets out what petrol actually does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
What petrol in a diesel does to the engine
Diesel does two tasks on its way through an engine. It ignites, and before it combusts it protects. Made to very fine tolerances, the fuel injectors and your pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Of these two jobs, petrol manages the first poorly and the second never. It is thinner than diesel and takes 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's where the rattling comes from.
The shape of the problem is plain once you put those together. Not contact but circulation is what causes the harm. Where that petrol is only in the tank, it is a fault of fuel, nothing more. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
Greenside, petrol in a diesel: four cases, from mild to serious
The best case there can be: filled up, never started. Just your tank has petrol in it, and so the job is clearing your tank and flushing your system where your car stands. This scenario can only really take place at a forecourt: anywhere else, your car got there by being driven.
Started for a moment, or just the ignition on. Once primed, the system has pulled petrol out of that tank up to the fuel filter and the fuel lines. That's usually still an easy task — a drain, a flush, and your filter seen to.
Your pump now spent a couple of miles on thinned fuel — that is what driving it does. The work is that tank, the fuel lines, the fuel filter and clean fuel through the entire system, and how hard the car was driven counts as much as how far. A school run to Greenside Primary School is one thing. Driving as far as Manchester, under 5 miles away, makes a very different task — as does any mileage on the M60, under 3 miles from Greenside, with the engine labouring hard all the way.
Driven on till it protested — clattering, smoke, a lumpy idle, a soft throttle. The engine is telling you the fuel is no longer behaving like diesel. Whether it's the verge on Shakespeare Road, a lay-by or a side road, stop there then leave it. A vehicle stopped quickly very seldom has permanent damage, since the fuel drain and the flush, which still go first, take care of it.
What Greenside drivers get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mixture. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. A newer diesel runs its fuel through finer parts at higher pressure, which makes the lubrication matter more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up more motorists than any other. Feed diesel to a petrol engine and it usually won't run, so the driver stops — and the harm stops with them. While the pump grinds, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Running is not the same as fine.
An outdated workaround for a different fault lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol weakened is put back by it — and afterwards, your tank still contains that petrol.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the fuel filter and lines, waiting to go straight back through the pump at your next start. It's also truly dangerous to drain petrol into a can at the kerbside.
How it happens: petrol in a diesel
It is rarely carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it easy, and the error runs one way.
The moment habit stops matching the vehicle is the moment it happens. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A hurried fill on the way to Fairfield with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it occurs. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
Next time you fill up around Greenside: preventing petrol in a diesel
- The label is what matters, and so check the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- Inspect your filler flap. Many cars state the fuel type inside the flap or on the cap. Look at it on your first fill in any vehicle you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, for a home with one of each.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It sounds daft. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the pump.
- Noticing it mid-fill? Stop at once. A thinner mix follows from less petrol in the tank, yet your next step remains the same: do not start it.
Already put petrol in a diesel in Greenside?
The order of things is short, then. Starting it is out, and so is switching on your ignition. Yet at the forecourt, at Tesco or anywhere else? Ask the attendants to help you push the vehicle away from the pump. What got in, roughly how much, and whether it has run: tell us those when you ring 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — Greenside has a page just for it.
What makes one Greenside petrol in a diesel job cost more than the next
There is no fair single price for this, since the four scenarios above are four separate jobs. The situation itself does most of the work of moving your cost. Where the car is matters too, and whether a technician can safely get to it, after the share of petrol to what your tank holds.
That's why our technicians ask three questions before costing instead of after: what went in, how much, and whether it has run. Their answers are what change a range into one firm number.
About Greenside
Greenside is a suburban area in Greater Manchester, situated near the River Medlock and close to the city of Manchester. Greenside has a mix of housing types, but semi-detached homes are predominant, and its riverside setting provides a distinctive character. Greenside is located near several other suburban areas, including Droylsden and Openshaw, and is about 3.9 miles from Manchester city centre.
Greenside and Greater Manchester: where our fuel drain cover runs
Droylsden, Bottom of Woodhouses and Openshaw are among the spots near Greenside that the same vans work, answering petrol in diesel calls across Greenside's M postcode area. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
In Greenside and still at the pump?
No position is better: that is where you are. Leave the car switched off, and ring.