Petrol in a Diesel Car in Osmaston: How Worried Should You Be?
Not started? Then less anxious than you likely feel. Until the ignition primes the pump, your starter cranks, or the car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the honest reply to the first Osmaston query — "have I wrecked it?" — usually no. To leave the car like that, ring Petrol in Diesel then leave your motor switched off. Below, you will find what petrol really does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
Two tasks fall to diesel on its journey round a motor. Oiling comes before burning; it does both. The high-pressure fuel pump and the fuel injectors are designed to extremely fine gaps, and your diesel passing through them is what stops those surfaces from grinding against one another.
Petrol handles the first task badly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on that mixture to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
The shape of the trouble is clear when you put those together. Contact does not do the damage — movement does. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
Four scenarios our engineers see around Osmaston: how bad is petrol in a diesel?
Fuelled up, never started. The best case there can be. Being on 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 is drained and cleaned on the spot, and nothing more is needed.
A moment's running, or just the ignition on. Petrol has come out of the tank and reached your filter and your lines, because the fuel system has been primed. Usually little more than clearing, rinsing and seeing to the fuel filter, and so still simple.
Some miles driven, and your pump has spent every one of them labouring on diluted fuel. Tank, lines, filter, then fresh fuel run through the whole circuit: that's the work, and the way the vehicle was driven counts as much as the distance. The school run to Ashwood Spencer Academy is one matter. Getting as far as Derby, under 3 miles away, makes a very different task — as does any distance on the M1, under 10 miles from Osmaston, with your engine labouring hard all the way.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone uneven. That's your engine telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Marlborough Road, a lay-by, a side street — and leave the vehicle there. Long-term damage is very uncommon if a car is stopped quickly, and the drain and flush-through that still go first take care of it.
Osmaston drivers and the petrol in a diesel myths they hear
False: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mix is all you get, because topping up takes out nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
If anything, the opposite holds. Myth: "A modern diesel can cope with a bit of petrol." A modern diesel runs its fuel through more precise components at higher pressure, which makes the lubrication count more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it normally will not run, and so the motorist stops — and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. It doesn't put back what petrol has diluted, and that petrol is still in that tank later on.
The next start draws petrol back round your pump out of your lines and the fuel filter, where some of it sits after the engine has run. That is why a DIY tank drain doesn't sort it — a myth. Draining petrol into a can at the roadside is also really hazardous.
How petrol ends up: petrol in a diesel
It is rarely carelessness, and nobody does it on purpose. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol motor. That is how the forecourt makes it simple.
Routine and the car getting out of step is how it happens. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. A rushed fill on the way to Peartree with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that is when. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Preventing petrol in a diesel next time you fill up around Osmaston
- The label is what matters, and so read the petrol pump rather than the colour: in the UK unleaded handles are normally green and diesel black, but not on every forecourt.
- The first fill in a strange car is the time to check the filler flap — inside it, or on the cap, many vehicles state which fuel they take.
- One of each in the house? Mark the key to the diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It seems silly and it works.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to refuse a petrol nozzle, and aftermarket devices exist for the remainder. Count it as a backstop, then keep checking the petrol pump.
- Noticing it halfway? Stop there and then. A weaker mixture results from less petrol in that tank, but your next stage stays the same: don't crank it.
Put petrol in a diesel in Osmaston already?
In that case, there is just a short order of things. Don't fire it up, and don't turn your ignition on. The staff at the forecourt — whether at Sainsbury's itself or wherever you filled up — will normally help roll it clear of the petrol pump if you ask. What was put in, about how much, and whether it's run: tell us those when you ring 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate issue — Osmaston has a page all for it.
One petrol in a diesel task in Osmaston costs more than another. Why?
An honest single price doesn't exist here: four situations, four separate jobs. Mostly, the cost moves with which one you are in. Two things come after that: the petrol that was put in as a proportion of what the tank holds, then the spot the car is in and whether a technician can reach it safely.
Ahead of any quote, not after, come three questions: the fuel that went in, its quantity, and whether it has run. That's why. A range turns into a straight figure when the answers are in.
About Osmaston itself
Osmaston is a suburban area located near the city of Derby in Derbyshire, sitting at an elevation of 56 metres above sea level. Osmaston is characterized by its predominantly semi-detached housing stock, with the area being close to nearby places such as Allenton, Pear Tree, and Wilmorton. Osmaston has a population of approximately 6794 residents, and is situated about 2.1 miles from Derby city centre. Osmaston is also relatively close to the national transport network, being around 111.3 miles from London.
Osmaston and Derbyshire: where our fuel drain cover reaches
Petrol in diesel jobs in Osmaston — part of the DE postcode area — go to vans that likewise cover the spots about it, Allenton, Pear Tree and Wilmorton among them. The car doesn't need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the petrol pump in Osmaston, still?
Then you're in the best spot there can be. Keep it off. Ring.