Carlingwark: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely feel. Everyone in Carlingwark starts with "have I wrecked it?", and the honest answer is usually no: petrol resting inside the tank of any diesel remains harmless until priming, cranking or driving pulls it into the fuel system. Keep it that way: leave the motor off and ring Petrol in Diesel. The rest of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the engine?
Diesel has two tasks on its way through an engine. It lubricates to begin with, and only then does it burn. Designed to extremely fine clearances, your injectors and your pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Of these two tasks, petrol handles the first 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 equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the clattering.
The shape of the issue is plain when you put those together. Not contact but movement is what causes the damage. A tank with petrol in it is a fuel fault. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors further on.
Carlingwark, petrol in a diesel: four situations, from mild to significant
Filled up, and never started: no case is better. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol kept inside that tank alone, it's emptied and flushed on the spot, and nothing more is needed.
Ignition on, or started for a second. With the fuel system primed, your lines and filter now contain petrol that has come from the tank. Usually nothing more than clearing, flushing and sorting your filter, so still simple.
A couple of miles driven, and the pump has spent every one of them working on weakened fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way the work includes that tank, the lines, the filter and clean fuel through the whole system. On the school run to Churchstanton Primary School, the mileage is small. Getting as far as Exeter, under 25 miles away, makes a very different job — as does any miles on the M5, under 5 miles from Carlingwark, with your engine working hard all the way.
Driven on till it protested — knocking, smoke, a ragged idle, a dead throttle. What you are hearing is your engine signalling fuel that no longer behaves like diesel. Whether it's the verge on Broad Street, a lay-by or a side street, stop there then leave it. The drain and flush-through still go first, and they take care of it: if a vehicle is pulled over quickly, permanent damage is very rare.
Petrol in a diesel stories Carlingwark people hear
Myth: topping up to full with diesel makes it fine. It does not. A bigger tank of the same mixture is all it gives, because topping up takes out nothing. The idea behind the guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and nearer the opposite. Protection counts more on newer diesels, not less, since their fuel passes through more precise parts at higher pressure.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor usually means a motor that will not run: the driver stops, and so does the damage. A diesel fed petrol generally starts, idles and drives away as if nothing has happened, while the pump grinds. Fine and running are not the same at all.
Myth: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another issue. What petrol has diluted stays diluted, and the petrol remains in your tank anyway.
Myth: "Drain that tank yourself and you are sorted." After your engine has been run, some of that petrol is no longer inside your tank: it is in the fuel filter and the lines, and it goes straight back through the pump on your next start. Draining petrol into a can at the kerbside is also truly risky.
Why petrol in a diesel occurs so easily
Nobody does it on purpose, and it is rarely carelessness. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it simple, and the error runs one way.
Habit and the car getting out of step is when it happens. Courtesy car, hire car, or a vehicle that's brand new. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps now in a different order. A rushed fill en route to Tiverton Parkway with a train to catch. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Throw in a back seat full of children, a phone call or rain, and the hand wins.
How to prevent petrol in a diesel on your next fill-up around Carlingwark
- A green handle for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: many cars print the fuel there.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, in a home with one of each.
- It seems silly and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away and keep your mind on the petrol pump.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Spotting it halfway? Stop there and then. A weaker blend follows from less petrol inside the tank, but the next stage remains the same: don't crank it.
Carlingwark: already put petrol in a diesel?
The order of things is brief, then. Don't start the vehicle, and don't switch the ignition on. Ask the staff to help you push it away from the pump if you're still at the forecourt, whether that's Monument Fuels or somewhere else. What went in, about how much, and if it's run: tell us that when you phone 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Carlingwark, since AdBlue brings corrosion and deposits rather than lost protection.
Carlingwark petrol in a diesel tasks: why one costs more than another
Four separate tasks lie behind the four scenarios above — which is why there is no fair single price. Mostly, your cost shifts with which one you're in. Beyond that it is the share — how much petrol got in against how much the tank takes — and then where the vehicle is and whether a technician can get to it safely.
Three questions come first, before any quote, rather than after — what went in, how much, has it run — and that is the reason. With those replies, you get a straight figure rather than a range.
About Carlingwark itself
Carlingwark is a locality situated in a riverside setting in Devon, with an elevation of 226 metres. Carlingwark lies near the communities of Biscombe and Rosemary Lane, and is close to Bolham Water. Carlingwark is characterised by its predominantly detached housing stock, and is located approximately 20 miles from Exeter. Carlingwark has a population of around 508 people.
Across Devon and around Carlingwark: fuel drain cover
Petrol in diesel call-outs in Carlingwark — part of the EX postcode area — go to vans that also cover the places around it, Biscombe, Rosemary Lane and Bolham Water included. Our technicians drain wherever the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Carlingwark and still at the pump?
The best place there is, then — that is where you are. Keep it off. Phone.