How Worried Should You Be? Petrol in a Diesel Car in Derry Downs
Probably less than you are now — as long as nobody has started the car. "Have I wrecked it?" is the first question anyone around Derry Downs asks, and the truthful answer is normally no, since petrol resting in a diesel tank hurts nothing till it's drawn through the system — by ignition priming, by your starter, or by being driven. Petrol in Diesel is who to ring, with the motor left off, and so it remains that way. What petrol really does to a diesel, how to judge how far it's travelled, and how to keep it from happening again: that's the remainder of this page.
The motor and petrol in a diesel: what goes on
Two tasks fall to diesel on its route round a motor. Oiling comes before burning; it does both. What stops the surfaces inside the high-pressure pump and the injectors from wearing down against each other is the diesel passing through them — they're built to very fine clearances.
The second job petrol does not do at all, and the first it does poorly. A pump working on a petrol mix is wearing itself out, since petrol is runnier than diesel and takes away the protection the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where any knocking starts.
Seen together, they show the shape the problem has. Not contact but movement is what causes the harm. Where the petrol is only inside the tank, it is a fault of fuel, nothing more. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors downstream.
Petrol in a diesel around Derry Downs: how bad is it? Four cases
Filled but never started — as good as it gets. The petrol is in the tank and just that tank, and the job is a drain and a flush where the car stands. This is the one scenario that can only truly occur on a forecourt, as anywhere else your car has been driven to get there.
Ignition on, or started for a second. Once primed, the system has pulled petrol out of that tank up to the fuel filter and the lines. Usually nothing more than clearing, purging and seeing to your filter, and so still easy.
Your pump has worked a few miles on thinned fuel — that is what driving it meant. Tank, lines, filter, then clean fuel put through the entire circuit: that is this work, and the way the car was driven matters as much as the miles. A school run to St Philomena's Primary School is one thing. Getting as far as London, under 15 miles away, makes a very different task — as does any mileage on the M25, under 3 miles from Derry Downs, with the motor labouring hard the whole time.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is the engine signalling fuel that no longer runs like diesel. Pull up where you are — on the verge on Mungo Park Way, at the kerb, down a side road — and don't move it. What comes first is still the drain and flush-through, and that takes care of it, with lasting damage very rare if a car is stopped soon.
Petrol in a diesel myths Derry Downs motorists hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — the tank just holds more of the same blend. The assumption behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: a newer diesel copes with a bit of petrol. If anything, the reverse. Smaller parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication count more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most drivers than any other. Any petrol engine fed diesel generally will not run, and so the motorist stops and the harm stops with them. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, while the pump grinds. Fine and running are not the same thing.
An old fix for a separate fault is behind this one. Myth: "Add some two-stroke oil and drive the car home." It does not put back what petrol has thinned, and that petrol is still inside the tank later.
The next start draws petrol back round your pump from the fuel lines and the filter, where some of it sits after the motor has been run. That is why a DIY tank drain does not sort it — a myth. Besides, petrol emptied into a can by the road is truly dangerous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle mostly won't go into a petrol car, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake straightforward, and just in one direction.
When routine and the vehicle stop matching, it happens. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. The pumps in a different order on a familiar forecourt. Filling up in a rush en route to St Mary Cray, with a train to catch. A new-to-you diesel Renault Clio, its first fuelling, and a motorist used to petrol: exactly when it occurs. Throw in a back seat full of kids, a phone call or rain, and habit wins.
Next time you fill up around Derry Downs: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Trust the label on the petrol pump, not the colour.
- Inspect the filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a vehicle you don't know.
- Mark your key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Daft, perhaps, but it does the trick.
- Put your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices are available 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 your tank makes a thinner mixture. What to do next does not change, though — still do not crank it.
Derry Downs: already put petrol in a diesel?
Then the order of things is brief. Leave it unstarted, with your ignition switched off too. If you're still on the forecourt — Texaco or anywhere else — ask the attendants to help you roll the vehicle clear of the pump. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it's been run.
Corrosion and deposits are the issue with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and see its own Derry Downs page.
One petrol in a diesel task in Derry Downs costs more than another. Why?
The four situations above are four separate tasks, so no single price for this would be honest. Chiefly, your cost shifts with which situation 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 our van can get to it safely.
Three queries come first, before any quote, rather than after — what got in, how much, has it run — and this is the reason. Given the replies, you get a straight figure rather than a range.
About Derry Downs and where it is
Derry Downs is a suburban area in south-east London, situated approximately 13 miles from central London. Derry Downs has a relatively low elevation of around 65 metres and is characterised by semi-detached housing. Derry Downs is located near other suburban areas such as St Mary Cray, Kevingtown, and Ramsden, and is home to a population of around 6128 residents.
Fuel drain cover in Derry Downs and across Greater London
The vans answering petrol in diesel call-outs around Derry Downs, in the BR postcode area, also work the places near it, St Mary Cray, Kevingtown and Ramsden included. Our technicians drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Derry Downs and still at the petrol pump?
Then you're in the best place there is. Keep it off. Ring.