How Worried Should You Be? Petrol in a Diesel Car in Putney
Unstarted? Then less worried than you likely feel. Until your ignition primes the pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank just sits there and does no harm. Which makes the truthful reply to the first Putney question — "have I ruined it?" — usually no. Leave your motor off then phone Petrol in Diesel — that is how you keep it like that. What petrol really does to a diesel, how to judge how far it's travelled, and how to keep it from happening a second time: that's the rest of this page.
The motor and petrol in a diesel: what goes on
Two jobs fall to diesel on its journey round a motor. It ignites, and before it combusts it lubricates. Very fine clearances go into the injectors and the high-pressure pump, and only your diesel running through stops those surfaces grinding together.
Petrol does the first job poorly and the second not at all. A pump working on a petrol mixture is wearing itself out, because petrol is runnier than diesel and takes away the lubrication your fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any clattering starts.
Seen together, they show the shape the problem takes. The damage is done by movement, not by contact. A tank with petrol in it is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors further on.
Petrol in a diesel around Putney: how serious is it? Four cases
Fuelled up, never started. The best case there is. At a forecourt, and genuinely only there, that petrol is still confined to your tank — since everywhere else your car was driven to reach it. The task is emptying and cleaning on the spot.
The ignition switched on, or a short start. Your system has been bled, and so petrol has left your tank and reached the fuel filter and the fuel lines. Still normally straightforward: drain, flush, and your filter seen to.
Driven a couple of miles. Now the pump has spent these miles labouring on diluted fuel. The work is your tank, the fuel lines, the filter and fresh fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. A school run to Our Lady of Victories Catholic Primary School is one matter. A run as far as Westminster, under 5 miles away, is a very different job. So is any mileage on the M4, under 5 miles from Putney, where the motor has been running hard throughout.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone lumpy. The engine is telling you the fuel is no longer acting like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Putney High Street. Lasting damage is very unusual if a car is pulled over soon, and the drain and flush that still come first sort it out.
Putney people and the petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. That advice supposes a diesel fuel system handles petrol by percentage. It doesn't.
"Current diesels can handle a little petrol" — a myth, and closer to the reverse. A newer diesel sends its fuel through more precise components at higher pressure, which makes the protection matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." Diesel in a petrol motor normally means a motor that won't run: the driver stops, and so does the damage. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, while the pump wears. A running engine does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different fault. None of what petrol thinned gets put back by it — and afterwards, the tank still contains the petrol.
Once the engine has been run, part of that petrol sits in the filter and your lines, not the tank — and your next start pulls it straight back through your pump. So the myth "drain that tank yourself and you're sorted" doesn't stand up. On top of that, petrol cleared into a can by the road is truly dangerous.
Petrol in a diesel: how does it happen?
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle generally will not fit a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and only in that direction.
The moment habit stops matching the car is the moment it happens. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. Your ordinary forecourt, its pumps suddenly in a different order. Fuelling up in a rush on the way to the nearest station, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it happens. Your hand does what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel at your next fill-up in Putney
- Green for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- The first fill in an unfamiliar vehicle is the time to check the filler flap — on it, or on the cap, many motors state the fuel to use.
- 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.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to refuse a petrol nozzle, and add-on devices exist for the remainder. Count it as a safety net, then keep checking the pump.
- As soon as you realise, stop: less petrol in your tank makes a weaker blend. What to do next doesn't change, though — still do not fire it up.
Putney: already put petrol in a diesel?
The order of things is short, then. Don't crank it, and do not turn the ignition on. Ask the attendants to help you push it away from the pump if you are still at the forecourt, whether that's Sainsbury's or anywhere else. What went in, roughly how much, and if it has run: tell us those when you call 0333 366 0103.
Corrosion and deposits form the problem with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own Putney page.
Why one petrol in a diesel job around Putney costs more than another
There is no honest single quote for this, because the four situations above are four separate tasks. Mostly, your cost shifts with which situation you're in. Two things come after that: the petrol that went in as a share of what that tank takes, then the place the vehicle is in and whether our van can get to it safely.
Three questions come first, before any quote, rather than after — what was put in, how much, has it run — and this is the reason. Those replies are what change a range into one firm number.
About Putney and its setting
Putney is a locality in southwest London, situated on the southern bank of the River Thames at an elevation of around 18 metres. Putney sits close to several nearby places, including Putney Heath, Fulham, and Southfields, and is approximately 5 miles from central London. Putney is predominantly composed of flat dwellings and has a population of around 8324 residents. Putney is well connected to the surrounding area, with nearby Westminster just 4.8 miles away.
Putney and Greater London: where our fuel drain cover reaches
Putney waits in the SW postcode area, and our teams that answer petrol in diesel call-outs there work the spots near it as well — Putney Heath, Fulham and Southfields among them. No need to bring your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
At the petrol pump in Putney, still?
In that case, you couldn't be in a better spot. Phone, and keep it turned off.