Minley: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you probably are. Until your ignition primes the pump, your starter cranks, or the car is driven, petrol in a diesel tank just rests there and does no harm. Which means the honest reply to the first Minley question — "have I wrecked it?" — usually no. Leave your engine off and call Petrol in Diesel — that is how you keep it like that. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and the way to make sure you never do it again.
What petrol in a diesel does to the motor
On its way through an engine, diesel has two tasks. It protects first, and after that does it burn. What keeps the surfaces inside your high-pressure pump and the injectors from grinding against each other is your diesel passing through them — they are made to very fine gaps.
Badly at the first, not at all at the second: that is petrol. It is thinner than diesel and removes the protection the fuel system depends on, so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the trouble is plain once you put those together. Contact doesn't do the harm — circulation does. Where the petrol is only inside your tank, it's a problem of fuel, nothing more. The beginning of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors beyond it.
Four situations our engineers see in Minley: how serious is petrol in a diesel?
Filled but never started — as good as it gets. At a forecourt, and really only there, that petrol is still limited to your tank — because anywhere 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. Once primed, the system has pulled petrol from that tank up to the fuel filter and your lines. That is usually still a simple job — a drain, a flush, and your filter dealt with.
A few miles driven, and the pump has spent every one of them running on thinned fuel. How hard the vehicle was driven counts as much as how far, and the work takes in that tank, the lines, your filter and fresh fuel through the whole circuit. On the school run to Potley Hill Primary School, the distance is short. A run as far as Winchester, under 50 miles away, is a very different job. So is any mileage on the M3, under 3 miles from Minley, where your engine has been running hard the whole time.
Driven on till it protested — rattling, smoke, a lumpy idle, a soft throttle. The fuel isn't acting like diesel any more, and your motor is saying so. Stop where you are — on the verge on Ripon Road, at the kerb, down a side road — and do not move it again. A vehicle stopped quickly very rarely has lasting damage, since the fuel drain and the flush, which still come first, deal with it.
Minley motorists and the petrol in a diesel stories they hear
Myth: topping up to full with diesel makes it fine. It does not. Nothing comes out when you top up — that tank just carries more of the same blend. A diesel fuel system does not tolerate petrol by percentage in the way that advice assumes.
If anything, the reverse holds. Myth: "A modern diesel can cope with a bit of petrol." More precise components and higher pressure are how a newer diesel runs its fuel, and that makes the protection matter more, not less.
"It starts, it drives, and so there is no harm" — the myth that trips up most drivers than any other. The motorist of a petrol motor fed diesel normally stops, since it will not run, and the harm stops there. Whilst the pump wears, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Fine and running are not the same at all.
An outdated workaround for a separate fault lies behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside that tank afterwards, and what it has diluted isn't put back.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol lies in your filter and lines, ready to go straight back through your pump on your next start. It's also really risky to drain petrol into a can at the kerbside.
How petrol ends up: petrol in a diesel
Carelessness is seldom the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol vehicle at all. So the mistake runs one way.
It happens when routine and the car stop matching. A new car, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. Filling up in a hurry en route to Fleet, with a train to catch. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is precisely the moment it takes place. Throw in a back seat full of children, a phone call or rain, and habit wins.
Avoiding petrol in a diesel next time you fill up in Minley
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in a new motor is the time to check the filler flap — inside it, or on the cap, many vehicles state the fuel to use.
- Good intentions count for less than a sticker or a fob in a bright colour on your diesel's key when a household has one of each. So mark it.
- 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 petrol pump. It sounds silly and it does the trick.
- Mistakes like this are easy to make whilst your mind is on something else, so your phone goes away.
- Add-on devices exist for cars without one, and some diesels come with a filler that won't accept a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- Less petrol means a thinner blend, so stop as soon as you notice — while remembering that the next step is unchanged. It's still not to start the car.
Put petrol in a diesel in Minley already?
Then, there's only a short order of things. Don't fire it up, and don't turn your ignition on. If you're still at the forecourt — Shell or anywhere else — ask the staff to help you roll it clear of the pump. Ring 0333 366 0103 next, with three facts — your fuel, the approximate volume, and if it has run.
Say so if it was AdBlue rather than petrol: it's a separate fault, with its own page for Minley, because AdBlue brings corrosion and deposits instead of lost protection.
Why one petrol in a diesel job around Minley costs more than another
The four scenarios above are four different jobs, so no single price for this would be fair. What moves your cost is chiefly which of them you are in. Where the vehicle is counts too, and whether a technician can safely get to it, after the proportion of petrol to what the tank holds.
Three queries come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. Their answers are what change a range into one firm number.
About Minley
Minley is a locality in Hampshire, situated inland at an elevation of around 101 metres, approximately 32.5 miles from London. Minley lies near several other small places, including Cricket Hill, Darby Green, and Frogmore, and is close to the city of Winchester, which is 27.7 miles away. Minley has a population of around 1041 people and is characterised by a predominance of flat housing. Minley is part of the wider South East region of England, with its residents likely commuting to nearby cities for work and amenities.
Minley and Hampshire: where our fuel drain cover runs
The teams answering petrol in diesel jobs in Minley, in the GU postcode area, also work the locations near it, Cricket Hill, Darby Green and Frogmore included. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our technicians work, and the car does not need to come to us.
Still at the petrol pump around Minley?
Then you are in the best spot there can be. Keep the car turned off, and ring.