How Worried Should You Be? Petrol in a Diesel Car in Diggs
If it hasn't been started, worry less than you likely are. Till the ignition primes your pump, your starter turns, or the car is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the truthful reply to the first Diggs question — "have I ruined it?" — usually no. Keep it like that: leave the motor off then call Petrol in Diesel. The rest of this page sets out what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two tasks. It lubricates to begin with, and only then does it burn. What stops the surfaces inside the high-pressure pump and the injectors from grinding against one another is your diesel flowing through them — they are built to extremely fine tolerances.
Petrol handles the first job badly and the second not at all. A pump running on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the lubrication the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where the clattering comes.
Put those together and the shape of the issue is plain. Contact does not do the damage — circulation does. Petrol in a tank is a fuel fault. 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 your fuel to your injectors further on.
How bad is petrol in a diesel? Four situations our engineers see around Diggs
Filled but not once started — the best it gets. At a forecourt, and genuinely only there, the petrol is still limited to your tank — since everywhere else your car was driven to get to it. The task is draining and purging on the spot.
Started for a moment, or only your ignition on. Petrol has left that tank and reached your filter and the fuel lines, because the system has been bled. Still generally simple: drain, flush, and your filter dealt with.
The pump now spent a few miles on thinned fuel — that's what driving the car meant. Tank, lines, filter, then fresh fuel put through the whole system: that is the work, and the way the car was driven counts as much as the miles. Driving the children to Haddenham St Mary's Church of England School is one kind of trip. Very different again: a trip to Oxford, under 15 miles away, or some distance on the M40, under 10 miles from Diggs, where your engine never stopped working hard.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. That is your engine telling you its fuel no longer is acting like diesel. Whether it is the verge on Whitecross Road, a lay-by or a side street, stop where you are and leave it. The drain and flush-through still come first, and they take care of it: when a vehicle is stopped early, permanent damage is very uncommon.
What Diggs drivers get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A fuller tank of the same mixture is all it gives, since topping up removes nothing. Percentage is not how a diesel fuel system copes with petrol, however much that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Protection matters more on current diesels, not less, since their fuel passes through finer parts at higher pressure.
One myth that catches drivers out: if it starts and drives, it must be unharmed. Any petrol engine fed diesel normally won't run, so the driver stops and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Running is not the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different fault. None of what petrol thinned is put back by it — and later, the tank still holds the petrol.
The next start draws petrol back round your pump out of the lines and the fuel filter, where some of it ends up once the engine has been run. That's why draining your tank yourself does not sort it — a myth. It is also really dangerous to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
Nobody does it on purpose, and it's rarely carelessness. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol car at all. So the slip runs one way.
The moment habit stops matching your car is the moment it happens. Courtesy car, hire car, or a motor that is new. Two cars on one driveway, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. Rushing for a train outside Haddenham & Thame Parkway and filling up en route. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Volkswagen Passat for the first time. Throw in rain, a phone call or a back seat full of children, and your hand repeats what it has always done.
Next time you fill up in Diggs: preventing petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is just a clue.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many vehicles state the fuel type there.
- One of each in the home? Label the key to the diesel — a bright fob, a sticker — since meaning to remember isn't enough.
- "Diesel", aloud, before you pick up the nozzle — each time a new or hired car gets its first tank. It sounds silly. It works.
- Mistakes like this are simple to make while your mind is on something else, and so the phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and add-on devices exist for the rest. Treat it as a safety net, then keep checking the petrol pump.
- Noticing it halfway? Stop at once. A weaker mixture results from less petrol inside the tank, but your next stage remains the same: don't crank it.
Diggs: already put petrol in a diesel?
Then the order of things is short. Never crank it, and do not switch your ignition on. Yet on the forecourt, at Gulf or anywhere else? Ask the staff to help you push it clear of the pump. What was put in, about how much, and whether it's run: tell us that when you phone 0333 366 0103.
Corrosion and deposits are the issue with AdBlue, where petrol means lost lubrication. So if it was AdBlue, say so — and read its own Diggs page.
Diggs petrol in a diesel jobs: why one costs more than another
An honest single price does not exist here: four situations, four separate jobs. Mostly, your cost shifts with which one you're in. Beyond that it is the share — how much petrol got in against how much that tank holds — and then where your car is and whether a van can get to it safely.
That is why we ask three questions before pricing instead of after: what was put in, how much, and if it's run. A range turns into a straight figure when the replies are in.
About Diggs itself
Diggs is a suburban area in Buckinghamshire, situated inland at an elevation of around 80 metres, and is located approximately 38.9 miles from London. Diggs is close to the city of Oxford, which is about 13.9 miles away, and is near other places such as Haddenham, Church End, and Fort End. Diggs has a population of around 2372 people and is characterised by predominantly detached housing.
Fuel drain cover across Buckinghamshire, Diggs included
Petrol in diesel jobs around Diggs — part of the HP postcode area — go to teams that also cover the places round it, Haddenham, Church End and Fort End included. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians drain, and your car doesn't need to come to us.
Diggs: still at the petrol pump?
In that case, you couldn't be in a better place. Switched off it remains; then ring.