Petrol in a Diesel Car in Derwent Haugh: How Worried Should You Be?
If it has not been started, worry less than you probably are. "Have I ruined it?" is the first thing anyone in Derwent Haugh asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing until it's dragged through the fuel system — by ignition priming, by the starter, or by driving. Keep it that way: leave your engine off then ring Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it's travelled, and how to keep it from happening again: that's the rest of this page.
The motor and petrol in a diesel: what goes on
Two jobs fall to diesel on its journey round a motor. Oiling comes before burning; it does both. Very fine tolerances go into the injectors and the high-pressure pump, and just your diesel running through stops their surfaces grinding together.
The second task petrol does not do at all, and the first it does badly. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the protection your 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 is where any knocking starts.
Combined, those leave the shape of the trouble plain. Not contact but movement is what causes the harm. A tank with petrol in it is a fuel problem. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Four scenarios our technicians see around Derwent Haugh: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there is. On a forecourt, and really only there, that petrol is still limited to that tank — because anywhere else the car was driven to reach it. The job is draining and cleaning on the spot.
A moment's running, or merely the ignition on. Once primed, your system has drawn petrol out of that tank up to the filter and the fuel lines. That is generally still an easy task — a drain, a flush, and your filter seen to.
Driven a few miles. Now your pump has spent these miles working on weakened fuel. How hard the car was driven counts as much as how far, and the work covers the tank, your lines, your filter and fresh fuel through the whole system. A school run to Swalwell Primary School is one thing. A run as far as Newcastle upon Tyne, under 3 miles away, is a very different task. So is any distance on the Central Motorway East, under 3 miles from Derwent Haugh, where the motor has been running hard the whole time.
Driven on until it protested — knocking, smoke, a lumpy idle, a soft throttle. That is your engine telling you its fuel no longer is acting like diesel. Whether it is the verge on Hollinside Road, a lay-by or a side street, stop there and leave it. A car stopped early very seldom has permanent damage, as the fuel drain and the flush-through, which still go first, sort it out.
Petrol in a diesel stories Derwent Haugh drivers hear
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 fuller tank, still the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." A current diesel runs its fuel through more precise components at higher pressure, which makes the lubrication matter more, not less.
"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 means a motor that won't run: the driver stops, and so does the damage. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, whilst the pump grinds. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. What petrol has thinned stays weakened, and that petrol remains inside the tank anyway.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in your filter and lines, waiting to go right back through your pump at your next start. Also, a can of petrol filled by the roadside is truly hazardous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it easy, and the error runs one way.
It takes place when routine and the vehicle stop matching. Courtesy car, hire car, or a motor that's new. Two motors on one drive, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. Fuelling up in a hurry en route to Metrocentre, with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
How to prevent petrol in a diesel at your next fill-up in Derwent Haugh
- A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Trust the label on the pump, not the colour.
- Check the filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on the first fill in any car you do not know.
- Label the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds silly and it does the trick.
- Mistakes like this are easy to make while your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices are available for cars without one. They are a backstop, not a reason to stop checking the pump.
- Less petrol makes a weaker mixture, and so stop as soon as you realise — while remembering that the next stage is unchanged. It's still not to start it.
Already put petrol in a diesel around Derwent Haugh?
The order of things is short, then. Leave it unstarted, with the ignition off too. Still on the forecourt, at Asda or anywhere else? Ask the attendants to help you push the car away from the pump. What got in, roughly how much, and whether it's run: tell us that when you phone 0333 366 0103.
If it was AdBlue and not petrol, say so. That is a different fault — corrosion and deposits instead of lost protection — and it has its own page for Derwent Haugh.
Derwent Haugh petrol in a diesel tasks: why one costs more than another
The four scenarios above are four separate jobs, so no single quote for this would be honest. Which of them you're in is mostly what moves your cost. Where your car is matters too, and whether a van can safely reach it, after the ratio of petrol to what your tank takes.
That is why our engineers ask three queries before costing instead of after: what got in, how much, and whether it's run. Given those answers, you get a straight figure instead of a range.
About Derwent Haugh and where it is
Derwent Haugh is a suburban area located on the River Derwent in Tyne and Wear, with semi-detached housing being the predominant type of accommodation. Derwent Haugh sits at a low elevation of around 8 metres, close to the city of Newcastle upon Tyne, which is approximately 2.9 miles away. Derwent Haugh is near several other suburban areas, including Swalwell, Paradise, and Beechgrove, and is part of the wider Newcastle upon Tyne urban area.
Derwent Haugh and Tyne and Wear: where our fuel drain cover reaches
Petrol in diesel jobs in Derwent Haugh — part of the NE postcode area — go to teams that also cover the locations round it, Swalwell, Paradise and Beechgrove among them. The car doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Derwent Haugh: still at the pump?
No position is better: that is where you now are. Phone, and leave it switched off.