Petrol in a Diesel Car in Tarland: How Worried Should You Be?
Not started? Then less anxious than you probably are. Petrol sitting in a diesel tank does nothing to the engine until something draws it through your fuel system — the ignition priming your pump, the starter, or driving on its own. So the fair answer to the first question anyone around Tarland asks, "have I ruined it?", is generally no. Petrol in Diesel is who to ring, with your engine left off, so it stays that way. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has got, and the way to make sure you don't do it again.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey round a motor. Before it ignites, it lubricates — and then it ignites. The high-pressure fuel pump and your injectors are made to extremely fine tolerances, and the diesel passing through them is what keeps those surfaces from wearing down against each other.
Petrol handles the first job poorly and the second not at all. It is thinner than diesel and strips away the lubrication your fuel system hinges on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
Taken together, they make clear what shape the issue has. Not contact but movement is what causes the harm. A tank with petrol in it is a fuel problem. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with your fuel to the fuel injectors downstream.
How bad is petrol in a diesel? Four scenarios our engineers see around Tarland
Filled but never started — as good as it gets. On a forecourt, and really only there, the petrol is still confined to that tank — since anywhere else your car was driven to reach it. The task is emptying and purging on the spot.
Your ignition switched on, or a short start. Your system has been bled, and so petrol has left that tank and reached your filter and the fuel lines. That's usually still a simple task — a drain, a flush, and the fuel filter dealt with.
Driven a couple of miles. Now the pump has spent those miles running on diluted fuel. Tank, lines, filter, then clean fuel run through the whole system: that is the work, and the way the vehicle was driven matters as much as the distance. Short trips, such as the school run to the local primary school, are one thing. Driving as far as Aberdeen, under 50 miles away, makes a very different job — as does any distance on the M90, over 50 miles from Tarland, with the motor running hard the whole time.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven till it complained. The fuel is not acting like diesel any more, and the engine is saying so. Leave it wherever it has stopped: a lay-by, a side street, the verge on Melgum Road. A vehicle stopped quickly very seldom has long-term damage, since the drain and the flush-through, which still come first, sort it out.
Petrol in a diesel stories Tarland motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed by topping up — you are left with a bigger tank, still the same mix. The idea behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel sends its fuel through smaller parts at higher pressure, which makes the protection matter more, not less.
"It starts, it drives, so no harm done" — the myth that catches more motorists than any other. A petrol motor fed diesel generally won't run, so the motorist stops and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, whilst your pump wears. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated fix for a different problem. What petrol has diluted remains weakened, and the petrol remains inside your tank anyway.
If the engine has been run, part of that petrol is in your filter and the lines, not the tank — and the next start sends it straight back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. Clearing petrol into a can by the roadside is also really dangerous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol motor at all. The forecourt makes it easy, and the error runs one way.
Habit and your car falling out of step is how it takes place. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the drive of the same household. A forecourt you know, only with its pumps laid out differently. Rushing for a train at the nearest station and fuelling up en route. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it happens. Add rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
How to prevent petrol in a diesel on your next fill-up in Tarland
- 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 counts.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: plenty of motors print the fuel type there.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a home with one of each.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- While you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the petrol pump.
- Less petrol makes a weaker mixture, so stop the moment you notice — though remembering that your next stage is unchanged. It is still not to start the car.
Petrol already in a diesel in Tarland? Begin here
Then the order of things is brief. Do not turn your ignition on, and don't start it. Ask the attendants to help you roll it clear of the petrol pump if you're still on the forecourt, whether that's Gulf or somewhere else. Call 0333 366 0103 next, with three facts — the fuel, the rough quantity, and if it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate issue — Tarland has a page just for it.
Why one petrol in a diesel job around Tarland costs more than another
The four situations above are four separate tasks, so no single price for this would be fair. Mostly, your cost shifts with which one you are in. Where the vehicle is counts too, and whether our van can safely get to it, after the proportion of petrol to what your tank holds.
What went in, how much, and if it has run — three queries our technicians ask before quoting, not after, for precisely that reason. The answers change a range into a straight figure.
About Tarland
Tarland is a small village in Aberdeenshire, situated on the banks of a river at an elevation of around 148 metres. Tarland lies approximately 28 miles west of Aberdeen and is surrounded by nearby places such as Coull, Ordie, and Coynach. Tarland has a population of around 633 people and features predominantly semi-detached housing. Tarland is located in a rural area, about 404 miles north of London.
Tarland and Aberdeenshire: where our fuel drain cover reaches
Petrol in diesel calls around Tarland — part of the AB postcode area — go to vans that likewise cover the locations round it, Coull, Ordie and Coynach included. Our engineers drain wherever the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in Tarland, right now?
The best place there is, then — that's where you are. Keep it off. Phone.