Brookmans Park: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as no one has started the vehicle. Until your ignition primes the pump, the starter turns, or the car is driven, petrol in a diesel tank just rests there and does nothing. Which means the honest reply to the first Brookmans Park question — "have I wrecked it?" — usually no. To leave the vehicle like that, call Petrol in Diesel and leave the engine alone. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and ways to make sure you don't do it again.
The motor and petrol in a diesel: what happens
Passing through an engine, diesel does two things at the same time. It combusts, and before it burns it lubricates. Extremely fine clearances are built into the fuel injectors and the high-pressure pump, and only the diesel flowing through stops those surfaces grinding together.
Petrol handles the first task 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 takes away the protection your fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the knocking comes.
Taken together, they make clear what shape the trouble has. It is circulation that causes the damage, not contact. All a tank with petrol in it amounts to is a fuel problem. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Four situations our engineers see around Brookmans Park: how bad is petrol in a diesel?
Fuelled, and never started: nothing beats it. Just your tank has petrol in it, and so the job is clearing your tank and purging the system where the vehicle sits. This scenario can only really happen on a forecourt: anywhere else, your car got there by being driven.
The ignition switched on, or a short start. Once primed, your system has drawn petrol from the tank as far as the fuel filter and the lines. Drain, flush, see to your filter: still normally easy.
Your pump has worked a couple of miles on weakened fuel — that is what driving the car does. The work is your tank, your lines, your filter and fresh fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. Short trips, such as the school run to Brookmans Park Primary School, are one thing. Driving as far as St Albans, under 10 miles away, makes a very different task — as does any miles on the A1(M), under a mile from Brookmans Park, with the motor running hard the whole time.
Driven till it protested. Clattering, an uneven idle, smoke, a throttle that has gone soft. That is your motor telling you its fuel has stopped acting like diesel. Pull up wherever you are — the verge on Brookmans Avenue, a lay-by, a side street — and leave the vehicle where it is. A car pulled over quickly very seldom has permanent damage, because the fuel drain and the flush-through, which still come first, sort it out.
Petrol in a diesel stories Brookmans Park drivers hear
Myth: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mixture is all you get, because topping up takes out nothing. A diesel fuel system does not tolerate petrol by percentage in the way that advice supposes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Protection matters more on current diesels, not less, because their fuel runs through finer parts at higher pressure.
"It starts, it drives, so no harm done" — the myth that trips up more drivers than any other. Feed diesel to a petrol motor and it generally won't run, so the motorist stops — and the harm stops with them. A diesel fed petrol generally starts, idles and drives away as if nothing has happened, while the pump grinds. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct issue. The petrol is still in your tank after that, and what it has diluted is not put back.
The next start draws petrol back round your pump from the lines and the fuel filter, where some of that sits once your engine has been run. That is why a DIY tank drain doesn't sort it — a myth. On top of that, petrol cleared into a can by the road is truly hazardous.
Petrol in a diesel: how does it occur?
It is seldom carelessness, and no one does it on purpose. A diesel nozzle generally won't fit a petrol motor, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake easy, and just in one direction.
Habit and the car falling out of step is how it occurs. A motor that's new to you — hired, on loan as a courtesy car, or just bought. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. A train to catch, and a hurried fill en route to the nearest station. The first fill-up in a diesel Skoda Octavia after years of driving petrol is precisely the moment it occurs. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
How to prevent petrol in a diesel at your next fill-up around Brookmans Park
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Inspect the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in any car you don't know.
- One of each in the house? Mark the key to your diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new car, say "diesel" out loud. Daft, yes, yet it does the trick.
- Whilst you're thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for cars without one, and some diesels come with a filler that won't accept a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- Stop as soon as you realise. Less petrol inside your tank makes a thinner mix. It doesn't change what to do next, which is still not to start it.
Petrol already in a diesel around Brookmans Park? Begin here
In that case, there is just a short order of things. Don't switch the ignition on, and don't start it. Ask the attendants to help you roll it clear of the pump if you're still at the forecourt, whether that's Esso or somewhere else. Then phone 0333 366 0103 and tell us what was put in, about how much, and if it has run.
If it was AdBlue instead of petrol, say so. That's a separate issue — corrosion and deposits instead of lost protection — and it has its own page for Brookmans Park.
One petrol in a diesel task around Brookmans Park costs more than another. Why?
An honest single quote does not exist here: four situations, four separate jobs. Mostly, the cost moves with which one you are in. After that it is the ratio — how much petrol went in against how much the tank takes — and then where the car is and whether a van can reach it safely.
Before any quote, not after, we ask three queries: the fuel that got in, the volume, and if it's run. That is why. Given those replies, there is a straight figure rather than a range.
About Brookmans Park, for a moment
Brookmans Park is a village in Hertfordshire, situated approximately 15 miles north of London and 6 miles south of St Albans. Brookmans Park sits in a relatively low-lying area at around 97 metres above sea level, near the villages of Water End, Bell Bar, and Swanley Bar. Brookmans Park has a population of around 1735 people, predominantly living in semi-detached houses.
Fuel drain cover across Hertfordshire, Brookmans Park included
Water End, Bell Bar and Swanley Bar are among the locations near Brookmans Park that the same vans work, answering petrol in diesel jobs across Brookmans Park's AL postcode area. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations we drain.
At the petrol pump in Brookmans Park, still?
Nothing beats it: that's where you now are. Leave it switched off, and ring.