How Worried Should You Be? Petrol in a Diesel Car in Coalburn
Likely less than you already are — provided nobody has started the vehicle. Until your ignition primes the pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which makes the truthful reply to that first Coalburn question — "have I wrecked it?" — usually no. Keep it like that: leave your motor off then call Petrol in Diesel. The rest of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to the engine
Diesel does two jobs on its way through a motor. Before it combusts, it protects — and then it burns. Made to extremely fine tolerances, the injectors and your pump rely on your diesel moving through them to keep their surfaces from wearing against one another.
Of these two jobs, petrol handles the first badly and the second never. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and takes away the lubrication your fuel system relies on. Petrol is also made to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any knocking comes.
Combined, those make the shape of the problem clear. Contact doesn't do the damage — movement does. All a tank with petrol in it amounts to is a fuel issue. 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 your fuel to the fuel injectors downstream.
Coalburn, petrol in a diesel: four cases, from mild to significant
Fuelled up, not once started. The best case there is. On a forecourt, and really only there, that petrol is still limited to your tank — since everywhere else your car was driven to reach it. The task is draining and cleaning on the spot.
Ignition on, or started for a moment. Petrol has left the tank and reached your filter and your lines, because the system has been bled. Still usually straightforward: drain, flush, and your filter sorted.
Your pump now spent a couple of miles on diluted fuel — that is what driving the car does. How hard the vehicle was driven matters as much as how far, and this work takes in the tank, the fuel lines, your filter and fresh fuel through the entire circuit. The school run to the local primary school is one matter. Very different a second time: a trip to Glasgow, under 25 miles away, or any distance on the M74, under 3 miles from Coalburn, where the engine kept working hard.
Driven on until it protested — knocking, smoke, a ragged idle, a dead throttle. The fuel is not acting like diesel any more, and your motor is telling you. Stop on the spot — on the verge on Dunn Crescent, at the kerb, down a side road — and don't move it. What comes first is still the fuel drain and flush, and that sorts it out, with lasting damage very uncommon if a car is stopped soon.
Coalburn drivers and the petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed when you top up — the tank simply holds more of the same mixture. Percentage is not how a diesel fuel system copes with petrol, however much that advice presumes.
Not so: a newer diesel copes with a bit of petrol. If anything, the opposite. Lubrication matters more on current diesels, not less, because their fuel runs through smaller parts at higher pressure.
This is the one that fools drivers. Myth: "If it starts and drives, there is no damage done." Feed diesel to a petrol engine and it usually will not run, so the driver stops — and the harm stops with them. While your pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive it home." It is an outdated workaround for a separate problem. What petrol has weakened stays thinned, and the petrol stays inside your tank regardless.
The next start sends petrol back round the pump out of the fuel lines and your filter, where some of it ends up once the motor has run. That is why draining the tank yourself doesn't leave you sorted — a myth. Emptying petrol into a can at the kerbside is also truly dangerous.
Why petrol in a diesel occurs at all
On purpose? Never. Through carelessness? Rarely, if ever. One way only, since of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol motor. That is how the forecourt makes it straightforward.
It occurs when habit and the vehicle stop matching. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. Racing for a train outside Lanark and filling up en route. Precisely the moment it occurs: after years of driving petrol, someone fills a diesel Volkswagen Tiguan for the first time. Throw in a back seat full of children, a phone call or rain, and habit wins.
Coalburn motorists: how to avoid petrol in a diesel next time
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on each forecourt. The label is what matters.
- In a motor you do not know, look inside the flap over your filler or at the cap before the first fill: many vehicles state the fuel there.
- One of each in the house? Label your key to the diesel — a bright fob, a sticker — because meaning to remember is not enough.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new car, say "diesel" out loud. Daft, yes, yet it does the trick.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- Add-on devices exist for cars 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 in the tank makes a thinner blend. What to do next does not change, though — still do not start the vehicle.
Coalburn: already put petrol in a diesel?
The order of things is short, then. Starting it is out, and so is switching on your ignition. The attendants at the forecourt — whether at Shell itself or wherever you filled up — will usually help push it away from the pump if you ask. Call 0333 366 0103 next, with three facts — your fuel, the rough amount, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate problem — Coalburn has a page just for it.
Coalburn petrol in a diesel tasks: why one costs more than another
There is no honest single price for this, because the four scenarios above are four separate tasks. What moves your cost is chiefly which of them you are in. Two things follow that: the petrol that got in as a share of what your tank takes, then the spot the car is in and whether a technician can get to it safely.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. Those replies turn a range into a straight figure.
About Coalburn and where it is
Coalburn is a village in South Lanarkshire, situated on the banks of a river at an elevation of 237 metres. Coalburn sits in a rural area, approximately 23 miles from Glasgow and 321 miles from London. Coalburn has a mix of housing types, with semi-detached homes being predominant. Coalburn is close to nearby settlements such as Auchlochan and Douglas West.
Fuel drain cover across South Lanarkshire, Coalburn included
Coalburn sits in the ML postcode area, and our vans that answer petrol in diesel call-outs there work the spots around it as well — Auchlochan, New Trows and Douglas West among them. No need to move the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations where we work.
Coalburn: still at the petrol pump?
Then, you couldn't be in a better place. Leave the vehicle switched off, and ring.