Petrol in a Diesel Car in Cornbank: How Worried Should You Be?
Likely less than you already are — as long as nobody has started the car. Until your ignition primes the pump, the starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which makes the honest reply to the first Cornbank query — "have I wrecked it?" — usually no. Petrol in Diesel is who to phone, with your engine left off, so it remains that way. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and the way to make sure you don't repeat it.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two tasks. Before it combusts, it protects — and then it combusts. What stops the surfaces inside the high-pressure pump and the injectors from grinding against one another is your diesel flowing through them — they are made to extremely fine gaps.
The second job petrol does not do at all, and the first it does poorly. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on the blend to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the knocking.
Put these together and the shape of the problem is clear. Contact does not do the harm — movement does. A tank with petrol in it is a fuel fault. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to your injectors downstream.
Cornbank, petrol in a diesel: four situations, from mild to serious
The best case there can be: filled up, never started. On a forecourt, and truly only there, the petrol is still confined to the tank — because anywhere else the vehicle was driven to reach it. The task is draining and rinsing on the spot.
Ignition on, or started for a moment. The fuel system has been primed, and so petrol has left that tank and reached the fuel filter and the lines. That's generally still an easy job — a drain, a flush, and the filter dealt with.
Your pump has spent a few miles on diluted fuel — that is what driving the car meant. How hard your car was driven counts as much as how far, and the work covers that tank, the lines, the fuel filter and fresh fuel through the whole circuit. The school run to the local primary school is one thing. A run as far as Edinburgh, under 10 miles away, is a very different task. So is any distance on the M8, under 10 miles from Cornbank, where the engine has been running hard throughout.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone uneven. The fuel is not acting like diesel any more, and your engine is saying so. Stop wherever you are — the verge on Brockwood Avenue, a lay-by, a side street — and leave the car where it is. A car pulled over quickly very seldom has permanent damage, as the fuel drain and the flush-through, which still go first, deal with it.
What Cornbank motorists get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. The assumption behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
If anything, the reverse holds. Myth: "A modern diesel can cope with a bit of petrol." A current diesel sends its fuel through more precise parts at higher pressure, which makes the protection matter more, not less.
"It starts, it drives, so no harm done" — the myth that trips up more drivers than any other. Diesel in a petrol motor normally leaves a motor that won't run: the motorist stops, and so does the harm. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump grinds. Fine and running are not the same at all.
Not so: a two-stroke additive lets you to drive home. It was an old fix, meant for another issue. None of what petrol weakened is put back by it — and later, that tank still contains the petrol.
The next start draws petrol back round your pump from your lines and your filter, where some of it sits after the engine has run. That is why draining the tank yourself does not leave you sorted — a myth. Emptying petrol into a can at the kerbside is also genuinely hazardous.
Petrol in a diesel: how does it happen?
It's seldom carelessness, and no one does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol motor. That's how the forecourt makes it easy.
The moment routine stops matching your car is the moment it occurs. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the driveway of the same household. Your normal forecourt, its pumps suddenly in a different order. Fuelling up in a rush en route to Curriehill, with a train to catch. Exactly the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Golf for the first time. Add a back seat full of children, a phone call or rain, and habit wins.
Cornbank people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Trust the label on the petrol pump, not the colour.
- Check your filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a vehicle you do not know.
- Mark your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems daft. 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 petrol pump.
- Add-on devices exist for cars without one, and some diesels come with a filler that won't accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in the tank means a weaker mix. What to do next doesn't change, though — still do not crank it.
Cornbank: already put petrol in a diesel?
Then, there is only a short order of things. Leave it unstarted, with your ignition off too. Ask the attendants to help you roll it clear of the petrol pump if you're still on the forecourt, whether that's Tesco or anywhere else. What went in, about how much, and whether it's run: tell us that when you phone 0333 366 0103.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate fault — Cornbank has a page all for it.
Cornbank petrol in a diesel tasks: why one costs more than another
An honest single quote doesn't exist here: four scenarios, four separate jobs. The situation itself does most of the work of moving your cost. The share counts next, meaning how much of your tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a technician.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. Their answers are what change a range into one firm number.
About Cornbank and its setting
Cornbank is a suburban area situated on the riverside in Midlothian, with a mix of semi-detached housing and a population of around 3688 residents. Cornbank sits at an elevation of 222 metres, close to the nearby towns of Penicuik and Cuiken, and is approximately 8.5 miles from Edinburgh. Cornbank forms part of the wider residential area surrounding Edinburgh, with easy access to the city and its amenities. Cornbank is also near Deanburn, another local community in the region.
Cornbank and Midlothian: where our fuel drain cover runs
Cornbank sits in the EH postcode area, and our vans that answer petrol in diesel jobs there work the places around it as well — Deanburn, Penicuik and Cuiken among them. The vehicle does not need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Cornbank?
The best position there is, then — that's where you are. Ring, and keep it switched off.