Lewisham: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you probably feel. "Have I ruined it?" is the first thing anyone around Lewisham asks, and the truthful answer is usually no, because petrol left in a diesel tank hurts nothing till it's drawn through your fuel system — by ignition priming, by your starter, or by being driven. Petrol in Diesel is who to call, with the motor kept off, and so it stays that way. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
The engine and petrol in a diesel: what goes on
On its way through a motor, diesel has two tasks. It protects first, and only then does it burn. The high-pressure fuel pump and your injectors are made to very fine clearances, and your diesel passing through them is what stops those surfaces from grinding against each other.
Of those two tasks, petrol manages the first badly and the second not at all. It's thinner than diesel and strips away the lubrication the fuel system hinges on, and 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 clattering comes from.
Combined, those leave the shape of the issue clear. Contact does not do the damage — circulation does. Petrol in the tank is a fuel problem. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Lewisham, petrol in a diesel: four situations, from mild to serious
Filled up, never started. The best case there is. That petrol is inside the tank and just your tank, and the task is a drain and a flush where the car sits. This is the one scenario that can only truly occur at a forecourt, because anywhere else your car has been driven to get there.
Started for a moment, or only your ignition on. Petrol has come out of that tank and reached the fuel filter and the fuel lines, because your system has been bled. That is generally still a simple job — a drain, a flush, and the filter seen to.
Your pump has worked a couple of miles on diluted fuel — that is what driving the car meant. Tank, lines, filter, then fresh fuel run through the whole circuit: that's the work, and the way your car was driven counts as much as the distance. On the school run to St Mary's Lewisham Church of England Primary School, the mileage is short. A run as far as London, under 10 miles away, is a very different job. So is any miles on the M11, under 10 miles from Lewisham, where the engine has been labouring hard the whole time.
Driven until it protested. Rattling, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer runs like diesel. Leave it wherever it stops: a lay-by, a quiet street, the verge on Lewisham High Street. Lasting damage is very rare if a car is stopped early, and the drain and flush that still go first sort it out.
Petrol in a diesel stories Lewisham motorists hear
False: topping up to full with diesel makes it fine. It does not. Nothing is removed when you top up — your tank simply carries more of the same mixture. The idea behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel sends its fuel through smaller parts at higher pressure, which makes the lubrication matter more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol motor and it normally will not run, and so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it usually fires up, ticks over and drives away as if nothing has happened — all while its pump is wearing. Running is not the same as fine.
An outdated workaround for a different fault lies behind this one. Myth: "Add some two-stroke oil and drive the car home." It doesn't put back what petrol has thinned, and the petrol is still in the tank later.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol sits in the filter and lines, ready to go straight back through the pump on the next start. It is also genuinely dangerous to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. One way only, since of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol car. That is how the forecourt makes it simple.
When habit and your car stop matching, it occurs. Hire cars, courtesy cars, and vehicles that are new to you. One petrol and one diesel on the drive of the same household. Your ordinary forecourt, its pumps now in a different order. A train to catch, and a rushed fill en route to Ladywell. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: precisely when it takes place. Add rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Avoiding petrol in a diesel next time you fill up around Lewisham
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the petrol pump's label; the colour is only a clue.
- In a motor you do not know, look inside the flap over your filler or at the cap before your first fill: many cars print the fuel type there.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, for a household with one of each.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- Mistakes like this are simple to make whilst your mind is on something else, so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the pump.
- As soon as you realise, stop: less petrol in your tank makes a thinner mixture. What to do next doesn't change, though — still do not fire it up.
Put petrol in a diesel in Lewisham already?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. Ask the staff to help you roll it clear of the petrol pump if you're still at the forecourt, whether that's Esso or somewhere else. Phone 0333 366 0103 next, with three answers — your fuel, the rough amount, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a separate fault — Lewisham has a page just for it.
Lewisham petrol in a diesel tasks: why one costs more than another
There's no fair single price for this, since the four scenarios above are four different jobs. Chiefly, the cost moves with which situation you are in. The share matters next, meaning how much of that tank is petrol, and then the position of the car and whether reaching it is safe for our van.
Three questions come first, before quoting, instead of after — what was put in, how much, has it run — and that is the reason. A range becomes a straight figure once those replies are in.
About Lewisham and where it is
Lewisham is a locality in south-east London, situated on the River Ravensbourne at an elevation of around 15 metres. Lewisham is located approximately 6 miles from central London and is close to nearby places such as Ladywell, Hither Green, and Crofton Park. Lewisham has a population of around 6175 people and is predominantly composed of flat housing. Lewisham is a residential area with a mix of old and new buildings, including modern flats and older housing stock.
Lewisham and Greater London: where our fuel drain cover runs
Lewisham sits in the SE postcode area, and the vans that answer petrol in diesel jobs there work the spots around it as well — Ladywell, Hither Green and Crofton Park among them. No need to move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
Still at the pump in Lewisham?
The best spot there is, then — that's where you are. Call, and leave it switched off.