Petrol in a Diesel Car in Horsey: How Worried Should You Be?
Far less than you likely are, provided it has not been started. Everyone in Horsey starts with "have I ruined it?", and the fair answer is normally no: petrol resting in that tank of a diesel stays harmless till priming, cranking or driving pulls it into the fuel system. Leave the engine off then phone Petrol in Diesel — that is how you keep it that way. Below, you will find what petrol really 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 jobs fall to diesel on its route round a motor. Oiling comes before burning; it does both. Designed to very fine gaps, your injectors and your pump depend on the diesel flowing through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that is petrol. It's thinner than diesel and takes away the protection your fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
Taken together, they show what shape the issue takes. It's circulation that causes the damage, not contact. Where that petrol is only inside that tank, it's an issue of fuel, nothing more. Whatever a worn pump sheds goes on, borne by the fuel, into the injectors downstream, which is why a pump that has been working on the petrol is where a mechanical problem starts.
Four scenarios our engineers see around Horsey: how bad is petrol in a diesel?
Filled but never started — as good as it gets. Only the tank has petrol in it, so the job is clearing that tank and purging your system where the car sits. This scenario can only truly happen at a forecourt: anywhere else, the car got there by being driven.
Started for a second, or just your ignition on. Once primed, the system has pulled petrol out of the tank up to the fuel filter and your lines. Still generally straightforward: drain, flush, and your filter sorted.
The pump now spent a couple of miles on thinned fuel — that is what driving the car meant. Mileage is only half of that; how hard it was driven counts equally. Either way the work runs to your tank, the lines, the fuel filter and clean fuel through the whole system. On the school run to Willowdown Primary School, the distance is small. A run as far as Wells, under 15 miles away, is a very different job. So is any miles on the M5, under a mile from Horsey, where the motor has been labouring hard throughout.
Driven on till it protested — clattering, smoke, a ragged idle, a dead throttle. What you are hearing is your motor signalling fuel that no longer acts like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Zeta Close. What goes first is still the fuel drain and flush, and that deals with it, with permanent damage very rare when a car is stopped quickly.
Horsey drivers and that petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice presumes.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. A current diesel sends its fuel through more precise components at higher pressure, which makes the protection matter more, not less.
"It starts, it drives, so no harm done" — the myth that trips up more people than any other. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the damage. While your pump grinds, a diesel fed petrol usually starts, idles and drives away as though nothing has happened. Fine and running aren't the same at all.
An old fix for a distinct problem lies behind this one. Myth: "Add some two-stroke oil and drive the car home." What petrol has diluted stays thinned, and the petrol remains inside the tank regardless.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol sits in the fuel filter and lines, waiting to go right back through your pump at your next start. Besides, petrol emptied into a can by the road is truly risky.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and no one means to do it. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol car at all. So the slip runs one way.
When habit and your car stop matching, it takes place. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. Filling up in a hurry en route to Bridgwater, with a train to catch. Years of petrol vehicles behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
How to prevent petrol in a diesel at your next fill-up in Horsey
- The label is what counts, so read the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on each forecourt.
- Plenty of cars state the fuel inside your filler flap or on the cap, and so check it on the first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember, in a home with one of each.
- Before the nozzle leaves the pump the first time you fill a hired or new car, say "diesel" out loud. Daft, perhaps, yet it works.
- Mistakes like this are straightforward to make while your mind is on something else, so the phone goes away.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- Stop as soon as you realise. Less petrol in the tank makes a weaker mixture. It doesn't change what to do next, which is still not to crank it.
Already put petrol in a diesel in Horsey?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. Ask the attendants to help you push it clear of the petrol pump if you're still at the forecourt, whether that's Shell or somewhere else. Call 0333 366 0103 next, with three facts — your fuel, the approximate volume, and if it has run.
Say so if it was AdBlue rather than petrol: it's a separate problem, with its own page for Horsey, because AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel job around Horsey costs more than another
Four different tasks sit behind the four scenarios above — which is why there is no fair single price. What moves your cost is chiefly which of them you are in. After that it is the ratio — how much petrol was put in against how much that tank holds — and then where the vehicle is and whether our van can reach it safely.
That's why our technicians ask three questions before costing rather than after: what was put in, how much, and if it's run. Their replies are what change a range into one firm number.
About Horsey itself
Horsey is a small village in inland Somerset, situated near the Somerset Levels and close to the nearby settlements of Slape Cross and Bradney. Horsey has a low elevation of around 5 metres, and its semi-detached housing stock is typical of many rural villages in the area. Horsey is located near the city of Wells, which is approximately 14.8 miles away, and is around 125.4 miles from London.
Horsey and Somerset: where our fuel drain cover runs
Slape Cross, Bradney and East Bower are among the locations near Horsey that the same teams work, answering petrol in diesel call-outs across Horsey's TA postcode area. We drain where your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the petrol pump in Horsey?
Then, you could not be in a better position. Leave it turned off, and ring.