Should You Worry? Petrol in a Diesel Car in Fen Drayton
Not started? Then less worried than you likely are. Until the ignition primes your pump, the starter turns, or the car is driven, petrol in a diesel tank simply waits there and does nothing. Which makes the truthful reply to that first Fen Drayton query — "have I wrecked it?" — usually no. To keep it like that, ring Petrol in Diesel then leave your engine switched off. What petrol actually does to a diesel, how to gauge how far it's travelled, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel does two tasks. Lubricating comes before burning; it does both. The high-pressure fuel pump and the fuel injectors are designed to very fine tolerances, and your diesel passing through them is what keeps those surfaces from wearing against each other.
Of those two tasks, petrol manages the first badly and the second not at all. A pump working on a petrol blend is wearing itself out, since petrol is runnier than diesel and strips out the protection 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 is where the rattling starts.
The shape of the issue is plain once you put those together. It's circulation that causes the harm, not contact. Any tank with petrol in it is a fuel problem. Whatever a worn pump sheds travels on, borne by your fuel, into your injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem starts.
Fen Drayton, petrol in a diesel: four cases, from mild to serious
The best case there can be: filled up, never started. Only the tank has petrol in it, and so the task is draining the tank and rinsing the system where your car sits. This scenario can only truly occur on a forecourt: anywhere else, your car got there by being driven.
Ignition on, or started for a moment. Petrol has come out of your tank and reached your filter and the fuel lines, since your system has been primed. Drain, flush, deal with the filter: still normally simple.
Driven a few miles. Now the pump has spent these miles working on weakened fuel. Tank, lines, filter, then clean fuel run through the whole system: that's this work, and the way the vehicle was driven matters as much as the mileage. On the school run to Fen Drayton Primary School, the miles is small. Any distance on the M11, under 10 miles from Fen Drayton, means the motor has worked hard throughout, and a run to Cambridge, under 10 miles away, is a very different job too.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. That is your engine telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Park Lane, a lay-by, a side street — then leave it there. Long-term damage is very uncommon if a vehicle is stopped soon, and the fuel drain and flush that still come first take care of it.
Fen Drayton drivers and that petrol in a diesel stories 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 by topping up — you are left with a bigger tank, still the same mix. That advice presumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. Finer components and higher pressure are the way a newer diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there's no damage done." The motorist of a petrol engine fed diesel normally stops, because it will not run, and the damage stops with them. Whilst the pump wears, a diesel fed petrol normally starts, ticks over and drives away as if nothing has happened. Being able to run is not the same as being fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, meant for another fault. None of what petrol thinned is put back by it — and later, that tank still contains the petrol.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in the fuel filter and lines, waiting to go right back through your pump on your next start. Draining petrol into a can by the roadside is also truly hazardous.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Seldom, if ever. One way only, because of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol motor. That is how the forecourt makes it easy.
When routine and your car stop matching, it takes place. A vehicle that's new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. A well-known forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Huntingdon. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Volkswagen Tiguan for the first time. Add a back seat full of children, a phone call or rain, and the hand takes over.
Next time you fill up around Fen Drayton: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before the first fill: plenty of cars state the fuel there.
- One of each in the household? Mark your key to your diesel — a coloured fob, a sticker — because meaning to remember isn't enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" aloud. Silly, perhaps, yet it works.
- Mistakes like this are straightforward to make whilst 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 reject a petrol nozzle, and aftermarket devices are available for the rest. Treat it as a safety net, then keep reading the pump.
- Stop the moment you realise. Less petrol in your tank means a weaker mix. It does not change what to do next, which is still not to crank it.
Put petrol in a diesel around Fen Drayton already?
The order of things is brief, then. Never fire it up, and don't switch the ignition on. If you're still on the forecourt — Shell or anywhere else — ask the staff to help you roll it clear of the petrol pump. What went in, about how much, and if it has run: tell us that when you call 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a different issue — Fen Drayton has a page just for it.
Fen Drayton petrol in a diesel jobs: why one costs more than another
There is no honest single price for this, because the four situations above are four separate jobs. The scenario itself does most of the work of moving your cost. Next it's the share — how much petrol was put in against how much your tank takes — and then where the vehicle is and whether a technician can get to it safely.
Ahead of any quote, not after, come three queries: the fuel that went in, the amount, and if it's run. That is why. Those answers change a range into a straight figure.
About Fen Drayton
Fen Drayton is a village in Cambridgeshire, situated on the shores of lakes and wetlands at a low elevation of around 12 metres. Fen Drayton lies near the cities of Cambridge and the smaller settlements of Fenstanton and Holywell, and is characterized by its predominantly detached housing stock. Fen Drayton is located within commuting distance of London, approximately 54.7 miles away, and is also close to the village of Conington.
Fuel drain cover around Fen Drayton and across Cambridgeshire
Fen Drayton waits in the CB postcode area, and our teams that answer petrol in diesel call-outs there work the spots around it as well — Fenstanton, Holywell and Conington among them. Our engineers drain where the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Fen Drayton and still at the petrol pump?
In that case, you couldn't be in a better spot. Keep the vehicle switched off, and ring.