Cargan: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, provided it has not been started. Everyone around Cargan begins with "have I wrecked it?", and the honest answer is generally no: petrol resting inside that tank of any diesel remains harmless till priming, cranking or driving pulls it into your fuel system. Petrol in Diesel is who to ring, with the motor kept off, so it remains that way. Further down, you will find what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
Inside your engine: what petrol in a diesel does
Passing through a motor, diesel is doing two jobs at once. It ignites, and before it burns it lubricates. What keeps the surfaces inside the high-pressure pump and the fuel injectors from grinding against one another is the diesel passing through them — they are designed to very fine tolerances.
Petrol handles the first task badly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system depends on, and any pump running on such a mix is wearing itself.
Together, those leave the shape of the trouble clear. Not contact but movement is what causes the damage. Petrol in the tank is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on.
How serious is petrol in a diesel? Four situations our technicians see in Cargan
The best case there is: filled up, never started. On a forecourt, and truly only there, the petrol is still confined to your tank — since everywhere else your car was driven to reach it. The task is draining and rinsing on the spot.
Started for a second, or just your ignition on. With your system primed, the lines and filter now hold petrol that came from the tank. That's normally still an easy job — a drain, a flush, and your filter seen to.
Driven a few miles. Now the pump has spent these miles running on weakened fuel. The work is that tank, the fuel lines, your filter and fresh fuel through the whole circuit, and how hard your car was driven counts as much as how far. Driving the children to the local primary school is one sort of trip. A run as far as Belfast, under 50 miles away, is a very different job. So is any miles on the M77, over 50 miles from Cargan, where the engine has been running hard throughout.
Driven on till it complained — clattering, smoke, a lumpy idle, a soft throttle. What you are hearing is the motor reporting fuel that no longer behaves like diesel. Leave it wherever it stops: a lay-by, a quiet street, the verge on Wallace Cottages. What comes first is still the fuel drain and flush-through, and that sorts it out, with long-term damage very rare when a car is stopped quickly.
Cargan motorists and that petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A bigger tank of the same mixture is all it gives, because topping up takes out nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer components: that is how a modern diesel moves its fuel, so the lubrication counts for more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools people. A petrol motor fed diesel generally will not run, and so the driver stops and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an outdated fix for a different issue. It does not put back what petrol has weakened, and that petrol is still in the tank later on.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol sits in the fuel filter and lines, waiting to go right back through the pump on the next start. On top of that, petrol drained into a can by the road is genuinely risky.
How it happens: petrol in a diesel
It is seldom carelessness, and nobody does it on purpose. A diesel nozzle mostly won't fit a petrol motor, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error straightforward, and only in that direction.
It happens when habit and the car stop matching. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. Rushing for a train outside the nearest station and fuelling up en route. Years of petrol vehicles behind you, a diesel Volkswagen Tiguan in front of you on the forecourt for its first tank — that is when. Add rain, a phone call or a back seat full of kids, and your hand does what it has always done.
How to avoid petrol in a diesel on your next fill-up in Cargan
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Check the petrol pump's label; the colour is only a hint.
- The first fill in a strange vehicle is the time to check the filler flap — on it, or on the cap, plenty of motors state the fuel to use.
- Label your key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds silly and it works.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck your phone away then keep your mind on the pump.
- Add-on devices exist for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside the tank makes a thinner mixture. What to do next does not change, though — still don't start it.
Already put petrol in a diesel in Cargan?
The order of things is short, then. Do not crank it, and do not turn the ignition on. The attendants on the forecourt — whether at the nearest petrol station itself or wherever you filled up — will usually help push it away from the pump if you ask. Then ring 0333 366 0103 and tell us what was put in, about how much, and whether it's run.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Cargan, because AdBlue brings corrosion and deposits instead of lost lubrication.
What makes one Cargan petrol in a diesel job cost more than the next
There is no honest single quote for this, because the four situations above are four different jobs. Which of them you are in is mostly what moves the cost. The proportion counts next, meaning how much of your tank is petrol, and then the location of the vehicle and whether getting to it is safe for a technician.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. With the replies, there is a straight figure instead of a range.
About Cargan and where it is
Cargan is a small locality in County Antrim, situated inland at an elevation of 179 metres. Cargan lies approximately 29 miles northwest of Belfast, near the villages of Newtown Crommelin, Martinstown, and Cloughmills. Cargan has a population of around 714 people, predominantly living in semi-detached housing. Cargan is located about 347 miles northwest of London, in the northern part of Northern Ireland.
Fuel drain cover around Cargan and across County Antrim
Newtown Crommelin, Martinstown and Cloughmills are among the locations near Cargan that the same teams work, answering petrol in diesel calls across Cargan's BT postcode area. The vehicle does not need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Cargan: still at the pump?
No position is better: that's where you are. Keep it off. Phone.