Cardenden: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — provided no one has started it. Everyone in Cardenden starts with "have I wrecked it?", and the honest answer is generally no: petrol left inside that tank of a diesel remains harmless until priming, cranking or driving draws it into the system. Petrol in Diesel is who to call, with your motor left off, so it remains that way. The rest of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what goes on
Two jobs fall to diesel on its journey round a motor. It lubricates first, and only then does it burn. The high-pressure pump and the fuel injectors are built to extremely fine tolerances, and your diesel passing through them is what stops those surfaces from grinding against each other.
Petrol handles the first job badly and the second not at all. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the lubrication your fuel system depends on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any rattling starts.
Put these together and the shape of the issue is plain. Contact doesn't do the damage — circulation does. A tank with petrol in it is a fuel fault. The beginning of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors beyond it.
Four situations our engineers see around Cardenden: how serious is petrol in a diesel?
Filled up, never started. The best case there can be. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held inside the tank alone, it's cleared and rinsed on the spot, and nothing more is needed.
A brief spell of running, or merely your ignition on. Petrol has come out of the tank and reached your filter and the lines, since your system has been primed. Usually little more than draining, purging and seeing to the fuel filter, so still straightforward.
Some miles driven, and your pump has spent each of them labouring on weakened fuel. Mileage is only half of that; how hard it was driven matters just as much. Either way this work runs to that tank, the fuel lines, the filter and clean fuel through the whole system. The school run to the local primary school is one matter. Any mileage on the M90, under 10 miles from Cardenden, means the engine has worked hard throughout, and a run to Dunfermline, under 10 miles away, makes a very different job as well.
Driven until it protested. Rattling, a ragged idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel has stopped behaving like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Cardenden Road. What goes first is still the drain and flush, and that sorts it out, with lasting damage very uncommon if a vehicle is stopped soon.
What Cardenden motorists get told about petrol in a diesel — and the myths in it
Myth: topping up to full with diesel makes it fine. It doesn't. Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. That advice presumes a diesel fuel system handles petrol by percentage. It does not.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. Lubrication counts more on modern diesels, not less, since their fuel passes through smaller parts at higher pressure.
Myth: "If it starts and drives, there's no damage done." This is the one that catches people. Feed diesel to a petrol engine and it usually will not run, and so the motorist stops — and the harm stops with them. While the pump wears, a diesel fed petrol normally starts, ticks over and drives away as though nothing has happened. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It is an old workaround for a different problem. What petrol has diluted stays thinned, and the petrol stays in that tank anyway.
Myth: "Drain the tank yourself and you're sorted." After the engine has been run, some of the petrol is no longer inside that tank: it's in the filter and the lines, and it goes straight back through your pump on your next start. On top of that, petrol cleared into a can by the road is genuinely dangerous.
How it happens: petrol in a diesel
Nobody does it on purpose, and it is rarely carelessness. A diesel nozzle generally won't go into a petrol car, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in that direction.
Routine and the car falling out of step is when it happens. Any 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. A familiar forecourt with the pumps in a different order. Racing for a train outside the nearest station and fuelling up en route. Years of petrol cars behind you, a diesel Renault Clio in front of you on the forecourt for its first tank — that's when. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up around Cardenden
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on every forecourt. The label is what matters.
- Plenty of vehicles state the fuel inside the filler flap or on the cap, so check there on the first fill in a car you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, in a home with one of each.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems silly. It works.
- Mistakes like this are simple to make while your mind is on something else, and so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available for the rest. Count it as a backstop, then keep checking the petrol pump.
- As soon as you realise, stop: less petrol in your tank makes a thinner blend. What to do next does not change, though — still don't start the car.
Put petrol in a diesel in Cardenden already?
Then the order of things is short. Starting it is out, and so is switching on the ignition. The staff at the forecourt — whether at Sainsbury's itself or wherever you filled up — will normally help roll it clear of the pump if you ask. Then phone 0333 366 0103 and tell us what was put in, roughly how much, and if it has run.
Say so if it was AdBlue instead of petrol: it's a separate issue, with its own page for Cardenden, because AdBlue brings corrosion and deposits instead of lost protection.
Why one petrol in a diesel task in Cardenden costs more than another
There is no honest single quote for this, because the four situations above are four separate jobs. What shifts your cost is chiefly which of them you're in. After that it's the share — how much petrol got in against how much your tank holds — and then where the car is and whether a technician can get to it safely.
What went in, how much, and whether it's run — three queries our technicians ask before costing, not after, for precisely that reason. Given the answers, there is a straight figure instead of a range.
About Cardenden
Cardenden is a village situated on the banks of a river in Fife, with a mix of terraced housing and other residential properties. Cardenden has a population of around 1790 people and is located near the towns of Dunfermline and Auchterderran. Cardenden sits at an elevation of 81 metres, providing views of the surrounding countryside. Cardenden is close to several nearby places, including Dundonald and Bowhill, and is within commuting distance of Dunfermline.
Fuel drain cover in Cardenden and across Fife
Cardenden waits in the KY postcode area, and our vans that answer petrol in diesel call-outs there work the spots near it as well — Dundonald, Bowhill and Auchterderran among them. No need to bring your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places we drain.
At the pump around Cardenden, still?
Then you are in the best place there can be. Call, and leave it switched off.