Chiswell Green: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, provided it has not been started. Till your ignition primes the pump, your starter turns, or the car is driven, petrol in a diesel tank simply sits there and does nothing. Which means the truthful reply to that first Chiswell Green query — "have I ruined it?" — usually no. To keep the vehicle that way, ring Petrol in Diesel and leave the engine switched off. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and ways to make sure you never do it again.
Petrol in a diesel: what does it do to your engine?
On its way through a motor, diesel has two jobs. It lubricates first, and only then does it burn. The high-pressure pump and the fuel injectors are built to extremely fine gaps, and the diesel passing through them is what keeps those surfaces from wearing down against one another.
Of those two tasks, petrol handles the first poorly and the second never. A pump working on a petrol mixture is wearing itself out, because petrol is thinner than diesel and takes away the protection the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where the clattering comes.
Together, those make the shape of the issue plain. Contact does not do the damage — movement does. Where the petrol is only inside that tank, it is a fault of fuel, nothing more. Whatever a worn pump sheds goes on, carried by your fuel, into the fuel injectors downstream, which is why a pump that has worked on the petrol is where a mechanical issue starts.
How serious is petrol in a diesel? Four scenarios our engineers see around Chiswell Green
Filled up, and not started: no case is better. The petrol is in the tank and just the tank, and the job is a drain and a flush where the car stands. This is the one scenario that can only truly occur at a forecourt, as anywhere else the vehicle has been driven to get there.
Ignition on, or started for a second. Your system has been primed, and so petrol has left the tank and reached the filter and the lines. Still normally simple: drain, flush, and the filter sorted.
A few miles driven, and the pump has spent every one of them labouring on diluted fuel. Tank, lines, filter, then clean fuel put through the whole system: that's the work, and the way the car was driven matters as much as the miles. On the school run to Killigrew Primary and Nursery School, the distance is small. Driving as far as St Albans, under 3 miles away, makes a very different job — as does any miles on the M25, under 3 miles from Chiswell Green, with the engine labouring hard the whole time.
Knocking, a ragged idle, smoke, a throttle gone soft: driven till it complained. That is the engine telling you its fuel has stopped behaving like diesel. Stop wherever you are — the verge on Chiswell Green Lane, a lay-by, a side street — and leave the car there. The drain and flush-through still come first, and they deal with it: when a vehicle is pulled over soon, long-term damage is very uncommon.
What Chiswell Green people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A bigger tank of the same mixture is all you get, because topping up takes out nothing. That guidance presumes a diesel fuel system handles petrol by percentage. It does not.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." Protection counts more on newer diesels, not less, because their fuel passes through smaller parts at higher pressure.
This is the one that catches people. Myth: "If it starts and drives, there is no harm done." 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 generally starts, idles and drives away as if nothing has happened, while the pump grinds. A running engine doesn't mean fine.
An old fix for a distinct problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." The petrol is still inside your tank afterwards, and whatever it has weakened isn't put back.
Myth: "Drain that tank yourself and you are sorted." After the motor has run, some of that petrol is no longer inside your tank: it is in the fuel filter and your lines, and it goes right back through the pump at your next start. Clearing petrol into a can at the roadside is also genuinely risky.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. One way only, since of the nozzles: the slimmer petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol car. That is how the forecourt makes it easy.
The moment routine stops matching the vehicle is the moment it happens. A car that's new to you — hired, on loan as a courtesy car, or brand new. Two cars on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. Filling up in a hurry on the way to Park Street, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it occurs. Add rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Chiswell Green people: how to prevent petrol in a diesel next time
- Read the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what counts.
- In a vehicle you do not know, look inside the flap over the filler or at the cap before your first fill: plenty of motors state the fuel type there.
- Mark your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new car, say "diesel" aloud. Daft, yes, yet it does the trick.
- While you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Add-on devices exist for motors without one, and some diesels come with a filler that won't take a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- Noticing it halfway? Stop there and then. A thinner blend follows from less petrol inside your tank, yet your next step stays the same: do not start the vehicle.
Petrol already in a diesel in Chiswell Green? Begin here
Short and simple, then, is the order of things. Starting it is out, and so is turning on your ignition. The attendants on the forecourt — whether at Shell itself or wherever you filled up — will usually help push it away from the petrol pump if you ask. What was put in, roughly how much, and if it has run: tell us those when you phone 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and read its own Chiswell Green page.
Why one petrol in a diesel job around Chiswell Green costs more than another
Four different jobs sit behind the four scenarios above — which is why there is no honest single price. Chiefly, your cost shifts with which situation you're in. Where your car is counts too, and whether a technician can safely reach it, after the proportion of petrol to what the tank takes.
That's why our engineers ask three questions before costing instead of after: what went in, how much, and whether it has run. With those answers, there is a straight figure instead of a range.
About Chiswell Green and where it is
Chiswell Green is a village in Hertfordshire, situated near the city of St Albans and approximately 18 miles from London. Chiswell Green sits in a relatively low-lying area at an elevation of around 99 metres, surrounded by other local communities such as How Wood and Park Street. Chiswell Green has a population of around 2766 people, predominantly living in semi-detached housing.
Fuel drain cover across Hertfordshire, Chiswell Green included
Petrol in diesel calls around Chiswell Green — part of the AL postcode area — go to teams that also cover the spots about it, How Wood, St Julians and Park Street among them. You need not bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
In Chiswell Green and still at the petrol pump?
The best position there is, then — that is where you are. Ring, and keep it switched off.