Audlem: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, provided it hasn't been started. Everyone around Audlem begins with "have I ruined it?", and the fair answer is normally no: petrol left inside that tank of any diesel stays harmless until priming, cranking or driving pulls it into your fuel system. Petrol in Diesel is who to call, with the engine left off, and so it remains that way. The rest of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you a second time.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its journey through a motor. Before it combusts, it protects — and then it ignites. Your high-pressure pump and your injectors are built to very fine clearances, and your diesel passing through them is what keeps those surfaces from grinding against one another.
Of those two tasks, petrol handles the first badly and the second never. Being less viscous than diesel, petrol strips out the lubrication a fuel system needs, so a pump on that mixture to wear itself. It is equally made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
Together, those leave the shape of the issue plain. It's movement that causes the damage, not contact. Where that petrol is only in your tank, it's an issue of fuel, nothing more. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Four situations our engineers see in Audlem: how bad is petrol in a diesel?
Fuelled, and never started: no case is better. That petrol is inside that tank and only that tank, and the task is a drain and a flush where the vehicle stands. This is the one situation that can only truly occur at a forecourt, as anywhere else your car has been driven to get there.
Ignition on, or started for a second. Petrol has left the tank and got to the fuel filter and the lines, because the system has been primed. Usually nothing more than emptying, flushing and sorting the filter, so still easy.
Some miles driven, and your pump has spent every one of them running on diluted fuel. Mileage is only half of that; how hard it was driven matters equally. Either way the work includes your tank, the fuel lines, the filter and clean fuel through the entire system. A school run to Audlem St James' CofE Primary School is one thing. Any distance on the M6, under 10 miles from Audlem, means your engine working hard throughout, and a run to Stoke-on-Trent, under 15 miles away, is a very different task as well.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. What you are hearing is the motor signalling fuel that no longer acts like diesel. Leave it wherever it has stopped: a lay-by, a side street, the verge on Vicarage Lane. A vehicle stopped soon very rarely has lasting damage, as the drain and the flush, which still come first, take care of it.
Petrol in a diesel myths Audlem drivers hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed when you top up — the tank just holds more of the same mixture. That advice assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the opposite holds. Myth: "A modern diesel can cope with a bit of petrol." A newer diesel sends its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
This is the one that fools people. Myth: "If it starts and drives, there is no damage done." Feed diesel to a petrol engine and it usually won't run, and so the motorist stops — and the damage stops with them. Feed petrol to a diesel and it usually starts, idles and pulls away as if nothing happened — all while its pump is wearing. Running isn't the same as fine.
An outdated fix for a distinct issue lies behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has weakened, and the petrol is still inside the tank after that.
Myth: "Drain the tank yourself and you're sorted." After your engine has been run, some of that petrol is no longer inside the tank: it's in the fuel filter and the fuel lines, and it goes right back through the pump on your next start. Also, a can of petrol filled by the roadside is genuinely hazardous.
How petrol ends up: petrol in a diesel
A careless moment is seldom the cause, and no one means to do it. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
It occurs when routine and the car stop matching. Any motor that's new to you — hired, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. Your normal forecourt, its pumps now in a different order. A hurried fill en route to Wrenbury with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you at the forecourt for its first tank — that is when. With rain, a call coming in, or children to deal with, the hand simply does what it has always done.
How to avoid petrol in a diesel at your next fill-up around Audlem
- Green for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the petrol pump, not the colour.
- The first fill in a new vehicle is the time to check the filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use.
- Label your key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems daft and it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, and so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the pump.
- As soon as you notice, stop: less petrol in your tank makes a thinner mix. What to do next does not change, though — still do not crank it.
Already put petrol in a diesel around Audlem?
Then the order of things is brief. Leave it unstarted, with the ignition switched off as well. Yet on the forecourt, at the nearest petrol station or anywhere else? Ask the staff to help you roll the vehicle away from the pump. Then call 0333 366 0103 and tell us what went in, about how much, and if it's run.
If it was AdBlue and not petrol, say so. That is a separate issue — corrosion and deposits rather than lost protection — and it has its own page for Audlem.
Audlem petrol in a diesel jobs: why one costs more than another
The four scenarios above are four different tasks, so no single quote for this would be honest. Which of them you're in is mostly what shifts the cost. Where the vehicle is counts too, and whether our van can safely get to it, after the proportion of petrol to what the tank holds.
Ahead of any quote, not after, we ask three queries: your fuel that got in, the amount, and if it's run. That's why. Given the answers, there is a straight figure rather than a range.
About Audlem
Audlem is a village in Cheshire, situated on the banks of the River Weaver, with a mix of old and new buildings, including many detached houses. Audlem has a population of around 1225 people and is located near other small settlements such as Little Heath and Chapel End. Audlem sits at an elevation of 64 metres, close to the Shropshire border, and is about 14 miles from Stoke-on-Trent. Audlem is part of the wider North West region of England, approximately 143 miles from London.
Fuel drain cover across Cheshire, Audlem included
The teams answering petrol in diesel calls around Audlem, in the CW postcode area, also work the locations near it, Little Heath, Chapel End and Browns Bank included. The vehicle doesn't need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the pump around Audlem, right now?
Nothing beats it: that's where you now are. Keep it off. Call.