How Worried Should You Be? Petrol in a Diesel Car in Dale Brow
If it hasn't been started, worry far less than you likely are. Till the ignition primes the pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which makes the truthful reply to that first Dale Brow question — "have I wrecked it?" — normally no. Petrol in Diesel is who to call, with your motor kept off, and so it remains that way. The remainder 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 does not happen to you a second time.
Petrol in a diesel: what does it do to the engine?
Diesel does two tasks on its way through an engine. It combusts, and before it combusts it lubricates. The high-pressure fuel pump and your injectors are built to very fine clearances, and your diesel passing through them is what keeps those surfaces from wearing down against each other.
The second job petrol doesn't do at all, and the first it does badly. It is thinner than diesel and strips away the lubrication the system rests on, so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the clattering comes from.
Combined, those make the shape of the trouble clear. Contact doesn't do the damage — circulation does. Where the petrol is only inside that tank, it is an issue of fuel, nothing more. Once your pump has been working on that petrol, a mechanical fault has started: whatever is shed by a pump that's grinding is carried onward to the injectors with the fuel.
Four situations our technicians see in Dale Brow: how serious is petrol in a diesel?
Fuelled, and not started: nothing beats it. That petrol is inside the tank and just that tank, and the job is a drain and a flush where your car sits. This is the one scenario that can only really occur on a forecourt, since anywhere else the car has been driven to get there.
Started for a second, or only your ignition on. Your system has been primed, so petrol has left that tank and reached the fuel filter and the fuel lines. That is usually still an easy job — a drain, a flush, and the filter seen to.
Your pump now spent a couple of miles on thinned fuel — that's what driving it meant. How hard your car was driven matters as much as how far, and the work covers that tank, the lines, your filter and fresh fuel through the whole circuit. Driving the children to Prestbury CofE Primary School is one sort of trip. Any miles on the M56, under 10 miles from Dale Brow, means the motor has worked hard throughout, and a run to Manchester, under 15 miles away, makes a very different job as well.
Driven on till it complained — rattling, smoke, a ragged idle, a dead throttle. The engine is telling you the fuel is no longer acting like diesel. Whether it's the verge on Broad Walk, a lay-by or a side street, stop where you are and leave it. Lasting damage is very unusual when a car is pulled over soon, and the drain and flush that still go first take care of it.
Stories Dale Brow people hear about petrol in a diesel
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 — the tank simply holds more of the same blend. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." Protection counts more on modern diesels, not less, because their fuel runs through finer components at higher pressure.
The myth that catches people off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that won't run: the motorist stops, and so does the harm. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. Being able to run isn't the same as being fine.
An old workaround for a separate fault is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol diluted gets put back by it — and afterwards, your tank still contains that petrol.
Myth: "Drain the tank yourself and you are sorted." After your engine has been run, some of that petrol is no longer inside your tank: it is in your filter and your lines, and it goes straight back through the pump at your next start. Clearing petrol into a can at the kerbside is also really risky.
How does petrol in a diesel take place?
No one does it on purpose, and it's rarely carelessness. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol car at all. So the error runs one way.
Habit and the vehicle falling out of step is how it happens. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. The pumps in a different order on a well-known forecourt. A hurried fill en route to Prestbury with a train to catch. The first fill-up in a diesel Peugeot 308 after years of driving petrol is precisely the moment it takes place. Throw in a back seat full of kids, a phone call or rain, and habit wins.
Avoiding petrol in a diesel next time you fill up around Dale Brow
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what matters.
- Many motors state the fuel inside your filler flap or on the cap, so check there on your first fill in a vehicle you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, for a house with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It sounds silly and it does the trick.
- While you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Some diesels have a filler designed to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop as soon as you realise. Less petrol inside the tank makes a thinner mix. It doesn't change what to do next, which is still not to fire it up.
Dale Brow: already put petrol in a diesel?
Then, there's just a short order of things. Starting it is out, and so is turning on the ignition. The staff on the forecourt — whether at Shell itself or wherever you filled up — will usually help roll it clear of the pump if you ask. What was put in, roughly how much, and if it has run: tell us that when you phone 0333 366 0103.
Say so if it was AdBlue instead of petrol: it is a different fault, with its own page for Dale Brow, since AdBlue brings corrosion and deposits instead of lost lubrication.
Dale Brow petrol in a diesel tasks: why one costs more than another
There is no honest single price for this, since the four situations above are four separate jobs. Chiefly, the cost shifts with which one you're in. Two things follow that: the petrol that went in as a share of what the tank holds, then the spot the vehicle is in and whether a technician can get to it safely.
That's why our technicians ask three queries before costing rather than after: what got in, how much, and whether it's run. Those replies change a range into a straight figure.
About Dale Brow
Dale Brow is a suburban area situated on the riverside in Cheshire, with a mix of detached housing and a population of around 1161 residents. Dale Brow sits at an elevation of 126 metres, close to nearby places such as Prestbury and Butley Town. Dale Brow is located near the city of Manchester, approximately 13.9 miles away, and is around 149.5 miles from London. Dale Brow remains a residential community with a scenic riverside setting.
Across Cheshire and around Dale Brow: fuel drain cover
Dale Brow sits in the SK postcode area, and our vans that answer petrol in diesel call-outs there work the places near it as well — Prestbury, Butley Town and Bradley Mount among them. We drain where your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Dale Brow: still at the petrol pump?
Then you are in the best spot there can be. Switched off it stays; then phone.