Woodcote: Petrol in a Diesel Car? How Worried to Be
If it has not been started, worry far less than you likely are. "Have I ruined it?" is the first thing everyone in Woodcote asks, and the honest answer is generally no, since petrol left in a diesel tank hurts nothing until it's drawn through the fuel system — by ignition priming, by the starter, or by driving. To leave the car like that, phone Petrol in Diesel and leave the motor switched off. What petrol really does to a diesel, how to gauge how far it has travelled, and how to keep it from happening again: that's the remainder of this page.
Your engine and petrol in a diesel: what goes on
Passing through a motor, diesel is doing two things at once. It lubricates to begin with, and only then does it burn. Designed to very fine gaps, the injectors and your pump depend on the diesel moving through them to keep their surfaces from wearing against one another.
The second task petrol does not do at all, and the first it does poorly. A pump running on a petrol mix is wearing itself out, because petrol is runnier than diesel and takes away the protection your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where any rattling comes.
Together, those leave the shape of the issue plain. Not contact but circulation is what causes the harm. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, borne by your fuel, into the injectors downstream, which is why a pump that has worked on that petrol is where a mechanical fault begins.
Petrol in a diesel in Woodcote: how bad is it? Four situations
Filled up, never started. The best case there is. Just that tank has petrol in it, and so the job is emptying the tank and flushing the system where your car sits. This scenario can only really take place on a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or only your ignition on. Petrol has left that tank and reached the fuel filter and the fuel lines, since the fuel system has been primed. Usually nothing more than draining, cleaning and seeing to the fuel filter, and so still straightforward.
The pump has worked a couple of miles on thinned fuel — that is what driving the car does. Tank, lines, filter, then clean fuel put through the whole circuit: that's the work, and the way the car was driven matters as much as the miles. The school run to Woodcote Primary School is one matter. Any distance on the M23, under 5 miles from Woodcote, means the motor has worked hard throughout, and a run to Westminster, under 15 miles away, is a very different task too.
Driven on till it protested — clattering, smoke, a lumpy idle, a soft throttle. What you are hearing is the engine signalling fuel that no longer runs like diesel. Leave it where it stops: a lay-by, a side street, the verge on Woodcote Valley Road. What comes first is still the drain and flush, and that sorts it out, with long-term damage very uncommon when a car is stopped quickly.
Stories Woodcote motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up removes nothing; it gives you a fuller tank of the same mixture. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. At higher pressure, through smaller parts: that's how a newer diesel handles its fuel, so the lubrication counts more, not less.
"It starts, it drives, so there is no harm" — the myth that trips up more drivers than any other. Diesel in a petrol motor normally means a motor that will not run: the motorist stops, and so does the harm. Feed petrol to a diesel and it usually starts, ticks over and pulls away like nothing has happened — all the while its pump is wearing. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. It does not put back what petrol has weakened, and the petrol is still inside that tank after that.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the fuel filter and lines, waiting to go straight back through the pump on your next start. On top of that, petrol emptied into a can by the road is truly hazardous.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and nobody means to do it. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol motor. That is how the forecourt makes it easy.
When habit and the vehicle stop matching, it occurs. Any vehicle that's new to you — hired, on loan as a courtesy car, or just bought. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. Fuelling up in a hurry en route to Reedham (London), with a train to catch. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Volkswagen Passat for the first time. Add a back seat full of children, a phone call or rain, and the hand wins.
Woodcote people: 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 pump's label; the colour is just a clue.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — inside it, or on the cap, many motors state which fuel they take.
- Mark your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds silly and it does the trick.
- While you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels have a filler designed to refuse a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the pump.
- Spotting it mid-fill? Stop at once. A weaker mixture results from less petrol inside your tank, but the next stage remains the same: don't crank it.
Put petrol in a diesel around Woodcote already?
Then, there is only a short order of things. Don't crank it, and do not turn the ignition on. If you're still on the forecourt — Tesco or anywhere else — ask the attendants to help you push the vehicle clear of the pump. Ring 0333 366 0103 next, with three facts — your fuel, the rough volume, and if it has run.
Say so if it was AdBlue instead of petrol: it is a different problem, with its own page for Woodcote, since AdBlue brings corrosion and deposits instead of lost lubrication.
Woodcote petrol in a diesel tasks: why one costs more than another
The four situations above are four different jobs, so no single quote for this would be honest. Which of them you are in is chiefly what moves your cost. The proportion counts next, meaning how much of that tank is petrol, and then the location of your car and whether getting to it is safe for a van.
Three questions come first, before quoting, rather than after — what got in, how much, has it run — and that is the reason. With those replies, you get a straight figure instead of a range.
About Woodcote and where it is
Woodcote is a suburban area in south London, situated approximately 12 miles from central London and near the towns of Purley and Coulsdon. Woodcote sits at an elevation of around 106 metres, with predominantly detached housing stock. Woodcote is close to Russell Hill and other residential areas, forming part of the wider suburban landscape of Greater London.
Woodcote and Greater London: where our fuel drain cover reaches
Woodcote sits in the CR postcode area, and the vans that answer petrol in diesel calls there work the places around it as well — Russell Hill, Purley and Coulsdon among them. The car doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Woodcote?
No position is better: that is where you are. Phone, and keep it switched off.