St Julians: Petrol in a Diesel Car? How Worried to Be
Probably less than you already are — as long as no one has started the vehicle. Until your ignition primes the pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank simply waits there and does nothing. Which means the honest reply to that first St Julians question — "have I wrecked it?" — normally no. Keep it like that: leave the motor off then phone Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it's gone, and how to stop it from happening again: that is the remainder of this page.
Inside your engine: what petrol in a diesel does
Two tasks fall to diesel on its route round a motor. It lubricates first, and only then does it burn. Made to very fine clearances, the injectors and the pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Of these two jobs, petrol manages the first badly and the second not at all. It is runnier than diesel and removes the protection your fuel system rests on, and 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 knocking comes from.
Put those together and the shape of the problem is clear. Contact doesn't do the damage — circulation does. Where that petrol is only inside that tank, it is a fault of fuel, nothing more. Whatever a worn pump sheds travels on, borne by the fuel, into the fuel injectors downstream, which is why a pump that has worked on that petrol is where a mechanical fault starts.
Petrol in a diesel around St Julians: how serious is it? Four cases
The best case there can be: filled up, not once started. Just that tank has petrol in it, so the task is draining your tank and rinsing your system where your car stands. This situation can only truly take place on a forecourt: anywhere else, the car got there by being driven.
A moment's running, or merely your ignition on. Petrol has come out of the tank and reached your filter and the fuel lines, because the fuel system has been bled. Still generally easy: drain, flush, and the filter seen to.
Driven a couple of miles. Now your pump has spent these miles working on weakened fuel. Miles is only half of it; how hard it was driven matters equally. Either way this work includes that tank, the lines, the fuel filter and clean fuel through the entire system. On the school run to St Adrian Roman Catholic Primary School, the mileage is small. Very different a second time: a trip to St Albans, under 3 miles away, or some distance on the M1, under 3 miles from St Julians, where the motor kept working hard.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven till it complained. What you are hearing is your motor reporting fuel that no longer behaves like diesel. Whether it is the verge on Falstaff Gardens, a lay-by or a side road, stop where you are and leave it. Permanent damage is very unusual if a car is pulled over early, and the drain and flush that still go first sort it out.
Petrol in a diesel stories St Julians drivers hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing is removed by topping up — you're left with a bigger tank, still the same mixture. That advice presumes a diesel fuel system tolerates petrol by percentage. It does not.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that's how a newer diesel handles its fuel, and so the lubrication counts for more, not less.
"It starts, it drives, so no harm done" — the myth that catches most motorists than any other. Diesel in a petrol motor generally leaves a motor that will not run: the driver stops, and so does the harm. Feed petrol to a diesel and it usually starts, idles and pulls away as if nothing happened — all the while its pump wears. Being able to run isn't the same as being fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old workaround, meant for another problem. That petrol is still inside your tank after that, and what it has thinned isn't put back.
The next start draws petrol back round the pump from your lines and the fuel filter, where some of that ends up once the motor has been run. That's why draining the tank yourself does not leave you sorted — a myth. Draining petrol into a can at the kerbside is also really dangerous.
How does petrol in a diesel take place?
No one does it on purpose, and it is seldom carelessness. The petrol nozzle is the smaller of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol car at all. The forecourt makes it simple, and the slip runs one way.
The moment habit stops matching your car is the moment it happens. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Rushing for a train outside St Albans Abbey and filling up en route. Exactly the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Golf for the first time. With rain, a call coming in, or children to deal with, the hand simply does what it has always done.
St Julians drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most usually do. Check the petrol pump's label; the colour is just a clue.
- Plenty of vehicles state the fuel type inside the filler flap or on the cap, and so check it on the first fill in any motor you don't know.
- One of each in the house? Mark your key to the diesel — a bright fob, a sticker — because meaning to remember is not enough.
- Before the nozzle leaves the petrol pump the first time you fill a hired or new motor, say "diesel" aloud. Silly, perhaps, yet it works.
- Mistakes like this are straightforward to make while your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse 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.
- The moment you notice, stop: less petrol in the tank means a thinner mix. What to do next doesn't change, though — still do not fire it up.
Already put petrol in a diesel in St Julians?
Short and simple, then, is the order of things. Starting it is out, and so is turning on the ignition. Yet on the forecourt, at Sainsbury's or anywhere else? Ask the attendants to help you roll the vehicle away from the petrol pump. Call 0333 366 0103 next, with three answers — your fuel, the approximate quantity, and whether it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate issue — St Julians has a page all for it.
One petrol in a diesel task in St Julians costs more than another. Why?
Four different jobs sit behind the four situations above — which is why there's no honest single price. The scenario itself does most of the work of moving the cost. Where the car is counts too, and whether our van can safely get to it, after the ratio of petrol to what your tank holds.
Three questions come first, before any quote, rather than after — what went in, how much, has it run — and that is the reason. A range becomes a straight figure when the answers are in.
About St Julians
St Julians is a suburban area located near St Albans in Hertfordshire, sitting at an elevation of around 104 metres in the inland landscape of the Eastern region. St Julians is close to nearby places such as St Stephens, Sopwell, and Chiswell Green, and is approximately 18.7 miles from London. St Julians has a population of around 4480 people and is characterised by predominantly detached housing.
St Julians and Hertfordshire: where our fuel drain cover reaches
St Julians sits in the AL postcode area, and our vans that answer petrol in diesel calls there work the locations near it as well — St Stephens, Sopwell and Chiswell Green among them. Our technicians drain wherever your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in St Julians, still?
In that case, you couldn't be in a better position. Ring, and keep it turned off.