Should You Worry? Petrol in a Diesel Car in Fairhill
If it has not been started, you can worry far less than you probably are. Everyone around Fairhill starts with "have I wrecked it?", and the fair answer is usually no: petrol left inside that tank of a diesel remains harmless till priming, cranking or driving draws it into the system. Keep it like that: leave the engine off then phone Petrol in Diesel. What petrol actually does to a diesel, how to gauge how far it's travelled, and how to keep it from happening a second time: that's the rest of this page.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey round a motor. Before it ignites, it protects — then it combusts. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing against each other is the diesel flowing through them — they're built to extremely fine gaps.
The second task petrol does not do at all, and the first it does badly. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where the rattling comes.
Seen together, they show what shape the trouble has. Not contact but circulation is what causes the damage. Petrol in the tank is a fuel problem. Whatever a worn pump sheds goes on, borne by the fuel, into your injectors further along, which is why a pump that has worked on the petrol is where a mechanical fault starts.
Petrol in a diesel around Fairhill: how serious is it? Four situations
Filled up, and never started: nothing beats it. On a forecourt, and really only there, the petrol is still confined to the tank — since everywhere else your car was driven to get to it. The task is draining and flushing on the spot.
The ignition switched on, or a brief start. Petrol has left the tank and reached the fuel filter and the lines, because the fuel system has been bled. That's usually still an easy job — a drain, a flush, and your filter seen to.
Some miles driven, and the pump has spent each of them labouring on weakened fuel. Distance is only half of it; how hard it was driven counts just as much. Either way this work runs to your tank, the fuel lines, the fuel filter and fresh fuel through the whole circuit. Short trips, like the school run to the local primary school, are one thing. A run as far as Glasgow, under 10 miles away, is a very different job. So is any mileage on the M74, under 3 miles from Fairhill, where your engine has been labouring hard the whole time.
Driven on until it protested — clattering, smoke, a ragged idle, a dead throttle. The fuel is not behaving like diesel any more, and your motor is saying so. Pull up wherever you are — the verge on Neilsland Road, a lay-by, a side street — and leave it where it is. Lasting damage is very rare if a vehicle is pulled over soon, and the drain and flush-through that still go first deal with it.
What Fairhill motorists get told about petrol in a diesel — and the stories in it
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed when you top up — that tank just holds more of the same mixture. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." Protection counts more on current diesels, not less, since their fuel passes through more precise components at higher pressure.
"It starts, it drives, so there is no harm" — the myth that trips up most people than any other. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the harm. Feed petrol to a diesel and it generally starts, ticks over and drives away like nothing happened — all the while its pump is wearing. Being able to run isn't proof of being fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a separate problem. None of what petrol diluted is put back by it — and later, the tank still contains that petrol.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol lies in your filter and lines, waiting to go right back through the pump at the next start. It is also genuinely risky to drain petrol into a can by the roadside.
Petrol in a diesel: how does it take place?
It is seldom carelessness, and no one does it on purpose. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol car at all. So the mistake runs one way.
When habit and your car stop matching, it happens. A motor that's new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. Fuelling up in a rush en route to Hamilton Central, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it takes place. Throw in rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Preventing petrol in a diesel next time you fill up in Fairhill
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Trust the label on the pump, not the colour.
- In a car you don't know, look inside the flap over the filler or at the cap before the first fill: plenty of vehicles state the fuel type there.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, in a household with one of each.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car needs its first tank. It seems silly. It works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Add-on devices are available for motors without one, and some diesels come with a filler that won't take a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside your tank means a thinner mixture. What to do next doesn't change, though — still don't crank it.
Put petrol in a diesel around Fairhill already?
Then, there's only a short order of things. Starting it is out, and so is turning on the ignition. The attendants at the forecourt — whether at BP itself or wherever you filled up — will normally help push it clear of the pump if you ask. What was put in, roughly how much, and whether it has run: tell us those when you ring 0333 366 0103.
If it was AdBlue instead of petrol, say so. That is a different fault — corrosion and deposits instead of lost protection — and it has its own page for Fairhill.
What makes one Fairhill petrol in a diesel task cost more than the next
The four scenarios above are four different tasks, so no single quote for this would be honest. Which of them you are in is mostly what shifts the cost. Where your car is matters too, and whether a van can safely reach it, after the ratio of petrol to what that tank holds.
That's why we ask three queries before pricing instead of after: what was put in, how much, and if it's run. A range turns into a straight figure when those replies are in.
About Fairhill and its setting
Fairhill is a suburban area situated on the riverside in South Lanarkshire, with a mix of semi-detached housing and local amenities. Fairhill lies close to the nearby places of Laighstonehall, Meikle Earnock, and Cadzow, and is approximately 9.8 miles from Glasgow. Fairhill has a population of around 6759 residents and is located at an elevation of 95 metres. Fairhill is part of the wider Glasgow urban area, with the city centre within commuting distance.
Fuel drain cover across South Lanarkshire, Fairhill included
Our teams answering petrol in diesel jobs around Fairhill, in the ML postcode area, also work the spots around it, Laighstonehall, Meikle Earnock and Cadzow among them. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our engineers work, and the vehicle does not need to move to us.
Fairhill: still at the petrol pump?
In that case, you could not be in a better place. Switched off it remains; then call.