Petrol in a Diesel Car in Halfway: How Worried Should You Be?
Less than you probably are, if it has not been started. Petrol resting in a diesel tank does nothing to the engine until something draws it through the fuel system — the ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first question anyone around Halfway asks, "have I ruined it?", is generally no. Leave your engine off and phone Petrol in Diesel — that keeps it that way. Below, this page sets out what petrol actually does inside a diesel, how far it might have gone, 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. It burns, and before it ignites it protects. The high-pressure pump and the fuel injectors are built to very fine clearances, and the diesel passing through them is what stops those surfaces from wearing against one another.
Of these two tasks, petrol handles the first poorly and the second not at all. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump running on the blend wearing itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is why you hear the clattering.
Combined, those make the shape of the problem clear. Contact doesn't do the damage — circulation does. Petrol in a tank is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical problem begins.
How bad is petrol in a diesel? Four scenarios our technicians see in Halfway
Fuelled up, never started. The best case there can be. Just that tank has petrol in it, and so the task is emptying that tank and rinsing the system where the car stands. This scenario can only truly happen at a forecourt: anywhere else, your car got there by being driven.
The ignition switched on, or a short start. The fuel system has been primed, and so petrol has left the tank and reached the filter and the fuel lines. Still generally easy: drain, flush, and the filter dealt with.
A few miles driven, and your pump has spent each of them working on weakened fuel. The work is your tank, the fuel lines, the filter and clean fuel through the whole circuit, and how hard the car was driven counts as much as how far. Short trips, like the school run to the local primary school, are one matter. Getting as far as Glasgow, under 10 miles away, makes a very different task — as does any distance on the M74, under 3 miles from Halfway, with the motor labouring hard the whole time.
Driven till it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. That is the motor telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Mill Road, a lay-by, a side street — then leave the vehicle where it is. A vehicle pulled over quickly very rarely has long-term damage, since the fuel drain and the flush, which still go first, deal with it.
Myths Halfway motorists hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up removes nothing; it gives you a bigger tank of the same mix. A diesel fuel system does not accept petrol by percentage in the way that advice presumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the opposite. More precise parts and higher pressure are the way a current diesel runs its fuel, and that makes the protection matter more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it usually will not run, and so the motorist stops — and the damage stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump grinds. Running is not the same as fine.
An old workaround for a distinct problem lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." It does not put back what petrol has diluted, and the petrol is still inside the tank afterwards.
The next start draws petrol back round your pump from your lines and the filter, where some of it ends up after the engine has run. That is why draining the tank yourself doesn't leave you sorted — a myth. Emptying petrol into a can at the kerbside is also truly risky.
Why petrol in a diesel occurs at all
On purpose? Never. Through carelessness? Seldom, if ever. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol car at all. So the error runs one way.
Habit and the vehicle falling out of step is how it takes place. A new motor, a hire car or a courtesy car. Two motors on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. A hurried fill en route to Newton with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: exactly when it takes place. With rain, a call coming in, or children to deal with, your hand simply does what it has always done.
Preventing petrol in a diesel next time you fill up around Halfway
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the petrol pump's label; the colour is just a clue.
- Many cars state the fuel type inside your filler flap or on the cap, and so check it on your first fill in a vehicle you don't know.
- Label the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- It sounds daft and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Mistakes like this are simple to make whilst your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the pump.
- Less petrol makes a thinner mix, and so stop the moment you realise — though remembering that the next step is unchanged. It is still not to fire it up.
Halfway: already put petrol in a diesel?
The order of things is brief, then. Do not start the vehicle, and don't turn the ignition on. The attendants at the forecourt — whether at the nearest petrol station itself or wherever you filled up — will normally help push it clear of the petrol pump if you ask. Then phone 0333 366 0103 and tell us what went in, roughly how much, and if it has run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Halfway page.
What makes one Halfway petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four situations, four separate jobs. Which of them you're in is chiefly what moves the cost. Two things follow that: the petrol that was put in as a share of what your tank holds, then the place your car is in and whether our van can reach it safely.
What went in, how much, and if it has run — three questions we ask before costing, not after, for exactly that reason. Their replies are what change a range into one firm number.
About Halfway, briefly
Halfway is a suburban area in South Lanarkshire, situated on the riverside at an elevation of 48 metres, with semi-detached housing being the predominant type of accommodation. Halfway lies approximately 5 miles from Glasgow, Scotland's largest city, and is surrounded by other nearby places such as Cairns, Flemington, and Westburn. Halfway has a population of around 6075 residents, making it a moderately sized community. Halfway is located relatively close to the urban centre of Glasgow, yet is far enough to maintain a distinct identity, being 339.8 miles from London.
Fuel drain cover across South Lanarkshire, Halfway included
Halfway rests in the G postcode area, and our teams that answer petrol in diesel calls there work the places near it as well — Cairns, Flemington and Westburn among them. No need to bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
In Halfway and still at the petrol pump?
Then, you could not be in a better place. Phone, and keep it switched off.