Burnhead: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you probably are. Until your ignition primes your pump, the starter turns, or your vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which means the honest reply to that first Burnhead question — "have I ruined it?" — normally no. Petrol in Diesel is who to phone, with your engine left off, and so it remains that way. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and the way to make sure you never repeat it.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey round a motor. Before it ignites, it lubricates — then it combusts. Extremely fine gaps are built into the fuel injectors and the high-pressure fuel pump, and just your diesel flowing through keeps those surfaces from grinding together.
Poorly at the first, not at all at the second: that's petrol. It's thinner than diesel and removes the protection your fuel system hinges on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the rattling comes from.
Put those together and the shape of the problem is clear. Not contact but circulation is what does the harm. Any tank with petrol in it is a fuel fault. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on.
Burnhead, petrol in a diesel: four situations, from mild to major
The best case there can be: filled up, not once started. At a forecourt, and genuinely only there, the petrol is still limited to that tank — because anywhere else your car was driven to get to it. The job is emptying and rinsing on the spot.
Ignition on, or started for a moment. With the fuel system primed, the lines and filter now hold petrol that has come from your tank. Still usually simple: drain, flush, and the fuel filter sorted.
A few miles driven, and your pump has spent every one of them labouring on thinned fuel. The work is your tank, your lines, the filter and fresh fuel through the entire system, and how hard the car was driven counts as much as how far. Driving the children to the local primary school is one sort of trip. Very different a second time: a run to Glasgow, under 15 miles away, or any distance on the M74, under a mile from Burnhead, where the engine kept labouring hard.
Driven on till it protested — knocking, smoke, a lumpy idle, a dead throttle. The engine is telling you the fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Maitland Bank, a lay-by, a side street — and leave the car there. The drain and flush still come first, and they deal with it: when a car is pulled over quickly, lasting damage is very uncommon.
Petrol in a diesel myths Burnhead people hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed when you top up — your tank just carries more of the same mixture. That advice supposes a diesel fuel system tolerates petrol by percentage. It does not.
If anything, the opposite is true. Myth: "A current diesel can cope with a bit of petrol." Lubrication counts more on newer diesels, not less, since their fuel passes through finer components at higher pressure.
"It starts, it drives, and so there is no harm" — the myth that trips up more people than any other. Diesel in a petrol motor normally leaves a motor that won't run: the driver stops, and so does the damage. Whilst your pump grinds, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Running doesn't mean fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old workaround for a distinct fault. It does not put back what petrol has thinned, and the petrol is still inside that tank later on.
If your engine has run, part of that petrol sits in the filter and the lines, not that tank — and your next start pulls it right back through the pump. So the myth "drain that tank yourself and you're sorted" doesn't hold. It is also genuinely hazardous to drain petrol into a can at the roadside.
Why petrol in a diesel takes place at all
Nobody does it on purpose, and it's rarely carelessness. A diesel nozzle mostly will not fit a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in that direction.
Habit and the vehicle falling out of step is how it takes place. Hire cars, courtesy cars, and cars that are new to you. Two motors on one driveway, one petrol, one diesel. Your usual forecourt, its pumps now in a different order. Racing for a train at Larkhall and fuelling up en route. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it occurs. Add rain, a phone call or a back seat full of kids, and the hand does what it has always done.
Avoiding petrol in a diesel next time you fill up in Burnhead
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, yet not on every forecourt. The label is what matters.
- The first fill in a new vehicle is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state the fuel they take.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, in a home with one of each.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems daft. It does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away.
- Some diesels come with a filler built to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- Less petrol makes a weaker mix, so stop the moment you notice — though remembering that your next step is unchanged. It is still not to start it.
Already put petrol in a diesel in Burnhead?
The order of things is brief, then. Never start the car, and do not turn your ignition on. The staff at the forecourt — whether at Shell itself or wherever you filled up — will usually help push it clear of the petrol pump if you ask. What got in, roughly how much, and if it has run: tell us those when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a separate problem — corrosion and deposits rather than lost lubrication — and it has its own page for Burnhead.
Burnhead petrol in a diesel jobs: why one costs more than another
The four scenarios above are four separate tasks, so no single quote for this would be fair. The situation itself does most of the work of moving the cost. The ratio matters next, meaning how much of your tank is petrol, followed by the position of your car and whether reaching it is safe for a van.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and that is the reason. The replies turn a range into a straight figure.
About Burnhead
Burnhead is a suburban area situated on the riverside in South Lanarkshire, with a mix of semi-detached housing and local amenities. Burnhead sits at an elevation of 107 metres, close to the nearby communities of Shawsburn, Meadowhill, and Hareleeshill. Burnhead is located near Glasgow, Scotland's largest city, and is approximately 331.6 miles from London. Burnhead has a population of around 3255 residents, living in a predominantly semi-detached housing stock.
Fuel drain cover around Burnhead and across South Lanarkshire
Petrol in diesel call-outs in Burnhead — part of the ML postcode area — go to teams that likewise cover the locations round it, Shawsburn, Meadowhill and Hareleeshill included. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our engineers drain, and your vehicle does not need to come to us.
In Burnhead and still at the pump?
Then you're in the best position there is. Keep the vehicle switched off, and ring.