How Worried Should You Be? Petrol in a Diesel Car in Greenfield
Far less than you probably are, provided it has not been started. Petrol sitting in a diesel tank does nothing to the engine until something pulls it through the fuel system — the ignition priming the pump, your starter, or the drive on its own. So the fair answer to the first query anyone around Greenfield asks, "have I wrecked it?", is generally no. To leave it that way, ring Petrol in Diesel then leave the motor alone. Read on for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and ways to make sure you never do it again.
The motor and petrol in a diesel: what goes on
Passing through a motor, diesel is doing two jobs at the same time. Oiling comes before burning; it does both. Your high-pressure pump and your injectors are built to extremely fine gaps, and your diesel passing through them is what stops those surfaces from grinding against each other.
Of these two jobs, petrol manages the first badly and the second not at all. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump running on that mixture to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
Together, those leave the shape of the trouble clear. 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 your fuel, into the injectors further along, which is why a pump that has worked on the petrol is where a mechanical issue starts.
How serious is petrol in a diesel? Four scenarios we see in Greenfield
The best case there is: filled up, never started. That petrol is in that tank and only that tank, and the task is a drain and a flush where the car stands. This is the one situation that can only really take place on a forecourt, because anywhere else the vehicle has been driven to get there.
Your ignition switched on, or a short start. The system has been primed, so petrol has left that tank and reached the filter and the fuel lines. Still generally easy: drain, flush, and the filter dealt with.
Driven a couple of miles. Now the pump has spent these miles working on weakened fuel. Distance is only half of it; how hard it was driven matters equally. Either way the work includes that tank, your lines, the fuel filter and clean fuel through the whole system. The school run to the local primary school is one matter. Very different a second time: a trip to Glasgow, under 3 miles away, or any distance on the M8, under a mile from Greenfield, where your engine kept running hard.
Driven on till it protested — rattling, smoke, a lumpy idle, a soft throttle. That's your engine telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Inveresk Quadrant, a lay-by, a side street — then leave it there. The fuel drain and flush still go first, and they deal with it: if a car is stopped quickly, permanent damage is very unusual.
Stories Greenfield motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A bigger tank of the same mix is all you get, since topping up removes nothing. A diesel fuel system does not accept petrol by percentage in the way that advice supposes.
If anything, the opposite is true. Myth: "A modern diesel can cope with a bit of petrol." A current diesel runs its fuel through smaller components at higher pressure, which makes the lubrication matter more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more motorists than any other. The driver of a petrol engine fed diesel usually has no choice but to stop, since it will not run, and the harm stops with them. Feed petrol to a diesel and it normally fires up, ticks over and pulls away as if nothing has happened — all while its pump is wearing. Running doesn't mean fine.
An outdated fix for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive it home." What petrol has thinned stays diluted, and that petrol stays in your tank anyway.
Myth: "Drain the tank yourself and you are sorted." Once the motor has been run, some of that petrol is no longer in your tank: it is in the filter and the lines, and it goes straight back through your pump at your next start. And, a can of petrol drained at the kerbside is genuinely risky.
Why petrol in a diesel takes place at all
A careless moment is seldom the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly will not go into a petrol car at all. So the slip runs one way.
The moment routine stops matching the vehicle is the moment it takes place. Hire cars, courtesy cars, and motors that are new to you. One petrol and one diesel on the drive of the same household. A well-known forecourt with the pumps in a different order. A rushed fill en route to Carntyne with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist used to petrol: precisely when it occurs. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it always has.
Next time you fill up around Greenfield: avoiding petrol in a diesel
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what matters.
- Many motors state the fuel type inside the filler flap or on the cap, and so check there on your first fill in any motor you don't know.
- One of each in the household? Label the key to your diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Before the nozzle comes off the petrol pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Silly, perhaps, yet it works.
- Mistakes like this are easy to make while your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for motors without one. They are a safety net, not a reason to stop checking the pump.
- Less petrol means a weaker mix, so stop as soon as you realise — though remembering that the next step is unchanged. It is still not to fire it up.
Already put petrol in a diesel around Greenfield?
Then the order of things is brief. Leave it unstarted, with your ignition switched off too. Yet on the forecourt, at Tesco or anywhere else? Ask the staff to help you push it clear of the pump. Ring 0333 366 0103 next, with three answers — the fuel, the approximate volume, and whether it has run.
If it was AdBlue and not petrol, say so. That is a separate problem — corrosion and deposits instead of lost protection — and it has its own page for Greenfield.
Greenfield petrol in a diesel jobs: why one costs more than another
The four situations above are four different tasks, so no single price for this would be fair. The scenario itself does most of the work of moving the cost. The proportion matters next, meaning how much of your tank is petrol, and then the location of the car and whether getting to it is safe for a technician.
That's why our technicians ask three queries before quoting instead of after: what went in, how much, and if it has run. Those replies change a range into a straight figure.
About Greenfield and its setting
Greenfield is a suburban area located on the riverside in Glasgow City, with a relatively low elevation of around 30 metres. Greenfield sits close to the city centre of Glasgow, approximately 2.6 miles away, and is near other local areas such as Barlanark and Shettleston. Greenfield has a population of around 6771 people and is predominantly composed of flat-type housing. Greenfield is situated in a densely populated urban environment, with easy access to the amenities of Glasgow.
Across Glasgow City and around Greenfield: fuel drain cover
Greenfield rests in the G postcode area, and the vans that answer petrol in diesel call-outs there work the places near it as well — Barlanark Place, Shettleston and Cranhill among them. Our engineers 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.
Still at the pump in Greenfield?
No position is better: that's where you now are. Keep it off. Ring.