Culverlane: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you probably feel. Everyone around Culverlane starts with "have I wrecked it?", and the fair answer is usually no: petrol left inside that tank of any diesel stays harmless till priming, cranking or driving draws it into your fuel system. Keep it that way: leave your engine off and ring Petrol in Diesel. Further down, this page sets out what petrol actually does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
Inside the engine: what petrol in a diesel does
Passing through a motor, diesel does two jobs at once. Before it burns, it lubricates — then it combusts. Extremely fine clearances go into the injectors and your high-pressure pump, and just your diesel flowing through keeps their surfaces from grinding together.
The second job petrol does not do at all, and the first it does badly. It's thinner than diesel and removes the lubrication your fuel system rests on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse 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 clear. It is circulation that causes the harm, not contact. Petrol in the tank is a fuel fault. Whatever a worn pump sheds goes on, borne by your fuel, into the fuel injectors downstream, which is why a pump that has worked on the petrol is where a mechanical issue begins.
Petrol in a diesel around Culverlane: how serious is it? Four cases
Filled up, not once started. The best case there is. That petrol is in the tank and just that tank, and the task is a drain and a flush where your car sits. This is the one situation that can only really take place at a forecourt, as anywhere else your car has been driven to get there.
Your ignition switched on, or a short start. With your system primed, the lines and filter already hold petrol that came from your tank. Usually nothing more than clearing, cleaning and sorting the filter, so still straightforward.
A couple of miles driven, and the pump has spent every one of them labouring on weakened fuel. How hard the vehicle was driven counts as much as how far, and the work covers that tank, the fuel lines, the filter and fresh fuel through the whole system. A school run to Diptford Parochial Church of England Primary School is one matter. Very different a second time: a run to Plymouth, under 25 miles away, or any distance on the M5, under 25 miles from Culverlane, where your engine kept running hard.
Driven on until it protested — knocking, smoke, a ragged idle, a soft throttle. The fuel is not acting like diesel any more, and your engine is telling you. Whether it is the verge on A385, a lay-by or a side street, stop there then leave it. A vehicle stopped early very rarely has permanent damage, because the fuel drain and the flush, which still come first, deal with it.
Culverlane drivers and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed when you top up — that tank simply carries more of the same mixture. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the opposite holds. Myth: "A current diesel can cope with a bit of petrol." Smaller parts and higher pressure are the way a newer diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." A petrol engine fed diesel normally won't run, so the motorist stops and the harm stops with them. While the pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Being able to run isn't proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different problem. It doesn't put back what petrol has diluted, and the petrol is still in that tank later.
Myth: "Drain that tank yourself and you're sorted." After your engine has been run, some of the petrol is no longer inside that tank: it's in your filter and the fuel lines, and it goes straight back through the pump on your next start. Besides, petrol emptied into a can by the road is genuinely dangerous.
Why petrol in a diesel occurs so easily
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol vehicle at all. So the error runs one way.
When routine and your car stop matching, it occurs. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. Your normal forecourt, its pumps now in a different order. A rushed fill on the way to Totnes with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that's when. With rain, a call coming in, or a car full of children to deal with, the hand simply does what it has always done.
Culverlane motorists: how to avoid petrol in a diesel next time
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the pump, not the colour.
- In a car you don't know, look inside the flap over your filler or at the cap before your first fill: many cars state the fuel there.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So mark it.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It seems daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to block a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a backstop, and keep checking the petrol pump.
- Noticing it halfway? Stop at once. A thinner blend results from less petrol in that tank, but your next stage stays the same: don't start it.
Already put petrol in a diesel in Culverlane?
Short and simple, then, is the order of things. Don't switch the ignition on, and don't crank it. If you're still on the forecourt — Blue Post Garage or anywhere else — ask the staff to help you push the car clear of the pump. Then ring 0333 366 0103 and tell us what was put in, about how much, and if it's run.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Culverlane page.
Why one petrol in a diesel job in Culverlane costs more than another
Four different tasks lie behind the four scenarios above — which is why there's no fair single quote. What shifts the cost is mostly which of them you're in. Where the vehicle is matters too, and whether our van can safely reach it, after the share of petrol to what that tank holds.
What got in, how much, and whether it has run — three questions our technicians ask before quoting, not after, for precisely that reason. With those answers, there is a straight figure instead of a range.
About Culverlane itself
Culverlane is a small locality in Devon, situated in a riverside setting with an elevation of around 114 metres. Culverlane lies near several nearby places, including Rattery, Tigley, and Brownston, and is approximately 17 miles from Plymouth. Culverlane has a population of around 580 people and is characterised by predominantly detached housing. Culverlane is located in the South West region of England, about 175 miles from London.
Across Devon and in Culverlane: fuel drain cover
Rattery, Tigley and Brownston are among the places around Culverlane that the same vans work, answering petrol in diesel calls across Culverlane's TQ postcode area. We drain where the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in Culverlane, still?
Then you're in the best spot there can be. Ring, and keep it switched off.