How Worried Should You Be? Petrol in a Diesel Car in Springfield
Not started? Then less worried than you likely are. Till the ignition primes the pump, your starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does no harm. Which means the truthful reply to the first Springfield question — "have I wrecked it?" — normally no. Leave the motor off then ring Petrol in Diesel — that is how you keep it like that. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
What petrol in a diesel does to the engine
Passing through a motor, diesel is doing two things at once. It ignites, and before it ignites it lubricates. Extremely fine gaps are built into the fuel injectors and the high-pressure pump, and just your diesel running through keeps those surfaces from grinding together.
Poorly at the first, not at all at the second: that's petrol. It's runnier than diesel and removes the lubrication the fuel system depends on, and so a pump running on a petrol mixture 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 knocking comes from.
Put those together and the shape of the trouble is plain. Contact doesn't do the damage — movement does. Petrol in a tank is a fuel issue. Once your pump has been labouring on that petrol, a mechanical problem has started: whatever is shed by a pump that's wearing is carried downstream to the injectors with your fuel.
How serious is petrol in a diesel? Four situations our technicians see around Springfield
The best case there can be: filled up, never started. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held in that tank alone, it's cleared and cleaned right where it stands, and nothing more is needed.
The ignition switched on, or a brief start. Once primed, the system has pulled petrol out of your tank as far as your filter and your lines. Drain, flush, see to the filter: still usually straightforward.
Your pump now spent a few miles on thinned fuel — that is what driving the car meant. The work is the tank, the lines, the filter and fresh fuel through the whole circuit, and how hard your car was driven counts as much as how far. Short trips, such as the school run to the local primary school, are one matter. Any mileage on the M90, under 15 miles from Springfield, means your engine working hard throughout, and a run to Dundee, under 15 miles away, is a very different job too.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. The engine is telling you your fuel is no longer acting like diesel. Whether it's the verge on The Cross, a lay-by or a side road, stop where you are and leave it. What goes first is still the fuel drain and flush-through, and that deals with it, with long-term damage very unusual if a car is pulled over early.
Springfield people and the petrol in a diesel myths they hear
False: topping up to full with diesel makes it fine. It doesn't. Nothing is removed by topping up — you are left with a fuller tank, still the same mix. Percentage is not how a diesel fuel system copes with petrol, whatever that guidance supposes.
If anything, the opposite is true. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through finer components: that is how a modern diesel moves its fuel, so the lubrication matters more, not less.
This is the one that fools people. Myth: "If it starts and drives, there's no damage done." A petrol engine fed diesel normally will not run, so the motorist stops and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump grinds. A running engine does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different fault. What petrol has diluted stays thinned, and that petrol remains in the tank anyway.
Myth: "Drain that tank yourself and you are sorted." After your engine has been run, some of the petrol is no longer in your tank: it is in the filter and your lines, and it goes straight back through your pump on your next start. It is also really risky to drain petrol into a can by the kerbside.
How it happens: petrol in a diesel
It's rarely carelessness, and nobody does it on purpose. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol car. That's how the forecourt makes it easy.
It takes place when routine and the vehicle stop matching. Hire cars, courtesy cars, and cars that are new to you. Two vehicles on one driveway, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. A train to catch, and a rushed fill on the way to the nearest station. The first fill-up in a diesel Renault Clio after years of driving petrol is precisely the moment it happens. With rain, a call coming in, or a car full of children to deal with, your hand just does what it has always done.
How to prevent petrol in a diesel on your next fill-up in Springfield
- Check the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on each forecourt. The label is what matters.
- Many motors state the fuel inside your filler flap or on the cap, so check it on the first fill in a vehicle you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a household has one of each. So label it.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Daft, perhaps, but it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the petrol pump.
- Some diesels come with a filler built to block a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Stop the moment you realise. Less petrol in your tank means a thinner mixture. It does not change what to do next, which is still not to fire it up.
Springfield: already put petrol in a diesel?
Short and simple, then, is the order of things. Leave it unstarted, with your ignition off too. The staff on the forecourt — whether at Tesco itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Call 0333 366 0103 next, with three answers — the fuel, the rough amount, and if it has run.
Corrosion and deposits are the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Springfield page.
One petrol in a diesel task around Springfield costs more than another. Why?
There's no honest single price for this, since the four situations above are four different jobs. Which of them you are in is mostly what moves the cost. The ratio counts next, meaning how much of that tank is petrol, followed by the location of your car and whether getting to it is safe for a technician.
Three questions come first, before quoting, instead of after — what was put in, how much, has it run — and this is the reason. The replies turn a range into a straight figure.
About Springfield itself
Springfield is a small village in Fife, situated on the banks of a river at an elevation of 43 metres. Springfield lies near the cities of Dundee and Perth, and is close to the nearby settlements of Mills, Kirkton of Cults, and Bow of Fife. Springfield has a population of around 772 people, predominantly living in semi-detached housing.
Fuel drain cover across Fife, Springfield included
Petrol in diesel call-outs in Springfield — part of the KY postcode area — go to teams that likewise cover the spots round it, Mills, Kirkton of Cults and Bow of Fife among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations we drain, and your car does not need to move to us.
At the petrol pump around Springfield, still?
The best place there is, then — that's where you are. Switched off it stays; then call.