Should You Worry? Petrol in a Diesel Car in Landywood
If it has not been started, you can worry far less than you probably are. Everyone in Landywood begins with "have I ruined it?", and the fair answer is normally no: petrol left in your tank of any diesel remains harmless till priming, cranking or driving draws it into the fuel system. Keep it like that: leave the motor off then ring Petrol in Diesel. The remainder of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
The motor and petrol in a diesel: what happens
On its way through a motor, diesel has two jobs. Lubricating comes before burning; it does both. Built to very fine gaps, the fuel injectors and your pump rely on your diesel flowing through them to keep their surfaces from wearing against one another.
Poorly at the first, not at all at the second: that's petrol. A pump working on a petrol mix is wearing itself out, since petrol is thinner than diesel and strips out the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where the knocking comes.
The shape of the problem is clear when you put those together. It's movement that does the harm, not contact. Petrol in a tank is a fuel fault. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with your fuel to your injectors downstream.
Four situations our technicians see around Landywood: how bad is petrol in a diesel?
Fuelled but never started — the best it gets. That petrol is inside your tank and only the tank, and the job is a drain and a flush where the vehicle sits. This is the one situation that can only truly take place on a forecourt, because anywhere else your car has been driven to get there.
Ignition on, or started for a moment. Once primed, the fuel system has pulled petrol from the tank up to your filter and the lines. That is normally still a simple job — a drain, a flush, and the fuel filter dealt with.
Driven a few miles. Now your pump has spent these miles running on diluted fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way this work includes the tank, your lines, your filter and clean fuel through the whole circuit. On the school run to Landywood Primary School, the miles is small. Driving as far as Wolverhampton, under 10 miles away, makes a very different job — as does any distance on the M6 Toll, under 3 miles from Landywood, with the engine running hard the whole time.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The engine is telling you the fuel is no longer behaving like diesel. Stop where you are — on the verge on Tower View Road, at the kerb, down a side road — and don't move it. The drain and flush-through still come first, and they take care of it: if a car is pulled over early, permanent damage is very rare.
Myths Landywood 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 will be." A fuller tank of the same mix is all it gives, since topping up removes nothing. That advice supposes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Smaller components and higher pressure are how a modern diesel runs its fuel, and that makes the protection matter more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools motorists. Feed diesel to a petrol motor and it normally won't run, so the motorist stops — and the harm stops with them. Whilst the pump wears, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Fine and running aren't the same thing.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another issue. That petrol is still inside the tank afterwards, and whatever it has diluted isn't put back.
Once your engine has run, part of the petrol sits in the fuel filter and the lines, not your tank — and the next start pulls it right back through your pump. So the myth "drain that tank yourself and you are sorted" does not hold. Clearing petrol into a can at the roadside is also genuinely dangerous.
Petrol in a diesel: how does it occur?
No one does it on purpose, and it's seldom carelessness. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol car at all. The forecourt makes it easy, and the mistake runs one way.
Routine and your car getting out of step is when it happens. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the drive of the same household. Your usual forecourt, its pumps suddenly in a different order. A hurried fill on the way to the nearest station with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist used to petrol: precisely when it occurs. With rain, a call coming in, or a car full of children to deal with, your hand just does what it always has.
Next time you fill up around Landywood: avoiding petrol in a diesel
- Green for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the pump, not the colour.
- The first fill in a new car is the time to check your filler flap — inside it, or on the cap, many vehicles state which fuel to use.
- Label your key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Before the nozzle leaves the pump the first time you fill a hired or new car, say "diesel" aloud. Silly, perhaps, but it works.
- Tuck your phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- As soon as you realise, stop: less petrol in that tank makes a weaker blend. What to do next doesn't change, though — still don't crank it.
Already put petrol in a diesel in Landywood?
The order of things is short, then. Leave it unstarted, with your ignition switched off as well. Still at the forecourt, at Esso or anywhere else? Ask the staff to help you push the car clear of the pump. Then call 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
If it was AdBlue and not petrol, say so. That is a different fault — corrosion and deposits rather than lost protection — and it has its own page for Landywood.
One petrol in a diesel job in Landywood costs more than another. Why?
Four separate jobs lie behind the four situations above — which is why there's no fair single quote. Mostly, the cost moves with which situation you are in. The ratio matters next, meaning how much of that tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a van.
Ahead of any quote, not after, come three queries: your fuel that was put in, its volume, and if it's run. That is why. The answers turn a range into a straight figure.
About Landywood itself
Landywood is a suburban area in Staffordshire, situated approximately 6 miles from Wolverhampton and 112 miles northwest of London. Landywood sits at an elevation of around 159 metres, characterised by its predominantly semi-detached housing stock. Landywood is located near other residential areas, including Upper Landywood, Newtown, and Great Wyrley, and is home to a population of around 3910 people.
Across Staffordshire and in Landywood: fuel drain cover
Upper Landywood, Newtown and Great Wyrley are among the locations around Landywood that the same vans work, answering petrol in diesel calls across Landywood's WS postcode area. The vehicle does not need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Landywood?
Nothing beats it: that is where you now are. Turned off it stays; then phone.