Rose Hill: Petrol in a Diesel Car? How Worried to Be
Far less than you probably are, if it has not been started. Until your ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank simply sits there and does no harm. Which makes the truthful reply to that first Rose Hill question — "have I ruined it?" — normally no. Keep it that way: leave the motor off and ring Petrol in Diesel. Below, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel really does
Passing through a motor, diesel is doing two things at the same time. Lubricating comes before burning; it does both. The high-pressure pump and the fuel injectors are built to extremely fine clearances, and the diesel passing through them is what keeps those surfaces from grinding against each other.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump on the blend to wear itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is where you hear the knocking.
The shape of the trouble is plain once you put those together. It is circulation that does the damage, not contact. A tank with petrol in it is a fuel issue. Whatever a worn pump sheds goes on, carried by the fuel, into the injectors further along, which is why a pump that has worked on the petrol is where a mechanical problem begins.
Petrol in a diesel around Rose Hill: how serious is it? Four cases
Fuelled but not once started — the best it gets. On a forecourt, and really only there, that petrol is still confined to that tank — since everywhere else the car was driven to reach it. The task is emptying and rinsing on the spot.
Started for a moment, or just your ignition on. Once primed, the fuel system has drawn petrol out of your tank as far as your filter and your lines. That is usually still a straightforward job — a drain, a flush, and the filter seen to.
Those few miles driven were your pump running on fuel diluted by petrol the whole way. Tank, lines, filter, then fresh fuel put through the whole circuit: that is the work, and the way your car was driven counts as much as the mileage. On the school run to St Paul's CofE Primary School, the distance is short. Any mileage on the M25, under 5 miles from Rose Hill, means the motor working hard throughout, and a run to Westminster, under 25 miles away, makes a very different task as well.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. The engine is telling you your fuel is no longer behaving like diesel. Whether it is the verge on Beresford Road, a lay-by or a side road, stop where you are then leave it. What goes first is still the fuel drain and flush, and that takes care of it, with permanent damage very uncommon if a car is pulled over quickly.
What Rose Hill motorists get told about petrol in a diesel — and the stories in it
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 bigger tank of the same mix. That guidance presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
"Newer diesels can handle a little petrol" — a myth, and closer to the opposite. More precise parts and higher pressure are how a newer diesel runs its fuel, and that makes the lubrication matter more, not less.
One myth that catches drivers out: if it starts and drives, it must be unharmed. The driver of a petrol motor fed diesel normally stops, because it will not run, and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, whilst your pump wears. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive it home." It's an old workaround for a different issue. None of what petrol weakened gets put back by it — and afterwards, the tank still contains that petrol.
The next start sends petrol back round the pump from the lines and the filter, where some of that sits after your engine has been run. That is why a DIY tank drain doesn't sort it — a myth. Also, a can of petrol drained at the roadside is truly hazardous.
How petrol ends up: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol vehicle at all. So the mistake runs one way.
It happens when habit and the car stop matching. A vehicle that's new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Dorking West. Years of petrol cars behind you, a diesel Volkswagen Tiguan in front of you at the forecourt for its first tank — that is when. The hand does what it has always done once you add rain, a phone call or a back seat full of kids.
How to avoid petrol in a diesel on your next fill-up around Rose Hill
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- The first fill in an unfamiliar motor is the time to check the filler flap — on it, or on the cap, many cars state the fuel they take.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a home has one of each. So mark it.
- Before the nozzle leaves the pump the first time you fill a hired or new car, say "diesel" aloud. Silly, yes, yet it does the trick.
- Tuck your phone away. This is an easy mistake to make while you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to block a petrol nozzle, and add-on devices exist for motors without one. They are a backstop, not a reason to stop reading the petrol pump.
- Stop as soon as you notice. Less petrol inside that tank means a thinner mixture. It does not change what to do next, which is still not to crank it.
Already put petrol in a diesel around Rose Hill?
The order of things is short, then. Starting it is out, and so is switching on the ignition. The staff on the forecourt — whether at BP itself or wherever you filled up — will usually help push it away from the pump if you ask. Phone 0333 366 0103 next, with three facts — your fuel, the approximate quantity, and if it has run.
If it was AdBlue rather than petrol, say so. That's a separate problem — corrosion and deposits and not lost lubrication — and it has its own page for Rose Hill.
One petrol in a diesel job in Rose Hill costs more than another. Why?
A fair single price does not exist here: four situations, four separate jobs. The situation itself does most of the work of moving your cost. Where the car is matters too, and whether a van can safely get to it, after the proportion of petrol to what the tank takes.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and this is the reason. A range becomes a straight figure when those replies are in.
About Rose Hill itself
Rose Hill is a suburban area in Surrey, situated on the riverside with an elevation of 81 metres, and is located approximately 21 miles from London. Rose Hill is characterized by its predominant housing type, which is flat, and is near to other places such as Dorking and Deepdene. Rose Hill has a population of around 6588 residents and is close to the nearby city of Westminster. Rose Hill is also near to Tower Hill, which is another nearby place of interest.
Fuel drain cover across Surrey, Rose Hill included
Rose Hill sits in the RH postcode area, and our vans that answer petrol in diesel calls there work the places near it as well — Dorking, Deepdene and Tower Hill among them. Our technicians drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Rose Hill and still at the petrol pump?
No position is better: that's where you now are. Turned off it remains; then phone.