Should You Worry? Petrol in a Diesel Car in Holywell
Not started? Then less anxious than you likely are. Until the ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which means the honest reply to the first Holywell question — "have I ruined it?" — usually no. Keep it that way: leave your engine off and phone Petrol in Diesel. Further down, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its route through a motor. Oiling comes before burning; it does both. Very fine gaps are built into your injectors and the high-pressure fuel pump, and only the diesel flowing through stops those surfaces grinding together.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on that mixture wearing itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the rattling.
Put those together and the shape of the trouble is clear. It is movement that does the damage, not contact. 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 the fuel to the injectors downstream.
Four scenarios our technicians see around Holywell: how serious is petrol in a diesel?
Filled up, not once started. The best case there can be. That petrol is in that tank and just your tank, and the task is a drain and a flush where the car stands. This is the one scenario that can only truly occur on a forecourt, since anywhere else the car has been driven to get there.
Started for a moment, or only your ignition on. Once primed, the system has pulled petrol out of that tank up to the fuel filter and the fuel lines. That is normally still a simple job — a drain, a flush, and the fuel filter seen to.
Your pump has spent a couple of miles on diluted fuel — that's what driving it meant. Mileage is only half of that; how hard it was driven matters equally. Either way the work includes your tank, the fuel lines, the filter and clean fuel through the whole circuit. The school run to Studham Village CofE Academy is one thing. Any mileage on the M1, under 5 miles from Holywell, means the motor has worked hard throughout, and a run to St Albans, under 15 miles away, makes a very different job too.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. That's the engine telling you its fuel has stopped behaving like diesel. Whether it's the verge on Studham Lane, a lay-by or a side road, stop there then leave it. What comes first is still the drain and flush, and that takes care of it, with lasting damage very rare when a car is pulled over soon.
Stories Holywell drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — your tank just holds more of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance assumes.
Not so: a current diesel copes with a bit of petrol. Rather, the reverse. At higher pressure, through more precise components: that's how a current diesel handles its fuel, and so the protection counts more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches people. The driver of a petrol motor fed diesel normally has no choice but to stop, since it will not run, and the damage stops there. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, while your pump grinds. Fine and running aren't the same thing.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different problem. It doesn't put back what petrol has weakened, and the petrol is still inside the tank later on.
If the motor has been run, part of the petrol sits in the fuel filter and your lines, not that tank — and the next start pulls it straight back through the pump. So the myth "drain your tank yourself and you're sorted" doesn't hold. Besides, petrol emptied into a can by the road is genuinely hazardous.
How does petrol in a diesel happen?
Carelessness is rarely the cause, and no one means to do it. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol car at all. The forecourt makes it simple, and the slip runs one way.
The moment routine stops matching the vehicle is the moment it occurs. Courtesy car, hire car, or a car that is brand new. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps suddenly in a different order. Fuelling up in a rush on the way to Tring, with a train to catch. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Holywell motorists: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Check the pump's label; the colour is just a hint.
- Inspect your filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, in a household with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It sounds silly and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away then keep your mind on the petrol pump.
- Add-on devices exist for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol in the tank means a weaker mix. What to do next does not change, though — still do not crank it.
Put petrol in a diesel in Holywell already?
Short and simple, then, is the order of things. Starting it is out, and so is switching on your ignition. Still on the forecourt, at Gulf or anywhere else? Ask the staff to help you push the car clear of the petrol pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Holywell, because AdBlue brings corrosion and deposits rather than lost lubrication.
What makes one Holywell petrol in a diesel job cost more than the next
A fair single quote doesn't exist here: four situations, four separate tasks. What moves your cost is mostly which of them you are in. Two things come after that: the petrol that was put in as a proportion of what that tank takes, then the spot the vehicle is in and whether our van can reach it safely.
That's why our technicians ask three queries before pricing rather than after: what was put in, how much, and whether it's run. Those answers are what turn a range into one firm number.
About Holywell
Holywell is a small village in Bedfordshire, situated in the rolling countryside of the Eastern region, with an elevation of around 186 metres. Holywell lies approximately 28.8 miles north of London and 10.2 miles northwest of St Albans, near the villages of Whipsnade and Studham. Holywell has a population of around 599 people, predominantly living in detached houses, and is surrounded by woodland areas such as Oldhill Wood.
Fuel drain cover around Holywell and across Bedfordshire
Petrol in diesel call-outs around Holywell — part of the LU postcode area — go to teams that likewise cover the locations round it, Whipsnade, Studham and Oldhill Wood included. We drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Holywell: still at the pump?
No position is better: that is where you are. Call, and leave it turned off.