Petrol in a Diesel Car in Merton Park: How Worried Should You Be?
Far less than you likely are, provided it has not been started. Till your ignition primes your pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank simply waits there and does no harm. Which means the truthful reply to the first Merton Park query — "have I wrecked it?" — normally no. To keep the vehicle that way, ring Petrol in Diesel then leave your motor switched off. Below, this page sets out what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you a second time.
Inside the engine: what petrol in a diesel really does
Two tasks fall to diesel on its route round a motor. It lubricates to begin with, and only then does it burn. Very fine gaps are built into your injectors and the high-pressure fuel pump, and just the diesel running through stops their surfaces grinding together.
Petrol handles the first task badly and the second not at all. A pump working on a petrol blend is wearing itself out, because petrol is thinner than diesel and strips out the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the clattering comes.
Put these together and the shape of the issue is plain. The harm is done by movement, not by contact. Any tank with petrol in it is a fuel fault. Whatever a worn pump sheds travels on, carried by your fuel, into the fuel injectors downstream, which is why a pump that has been working on that petrol is where a mechanical fault begins.
Petrol in a diesel around Merton Park: how serious is it? Four cases
Filled up, and never started: no case is better. Being on a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With that petrol held inside your tank alone, it is cleared and rinsed right where it stands, and nothing more is needed.
Ignition on, or started for a moment. Petrol has come out of that tank and reached your filter and your lines, since your system has been bled. Still normally simple: drain, flush, and your filter sorted.
Those few miles on the road meant your pump labouring on fuel diluted by petrol the whole way. The work is your tank, your lines, the fuel filter and fresh fuel through the entire circuit, and how hard the car was driven counts as much as how far. Short trips, such as the school run to Merton Park Primary School, are one thing. A run as far as Westminster, under 10 miles away, is a very different task. So is any miles on the M4, under 10 miles from Merton Park, where the engine has been running hard throughout.
It complained, and only then stopped: smoke, clattering, 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 Dorset Road, a lay-by or a side street, stop there and leave it. Permanent damage is very unusual if a car is pulled over soon, and the fuel drain and flush-through that still go first take care of it.
Myths Merton Park drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up takes out nothing; it gives you a bigger tank of the same mix. A diesel fuel system does not accept petrol by percentage in the way that advice assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. A current diesel runs its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
Myth: "If it starts and drives, there is no damage done." This is the one that catches motorists. The motorist of a petrol motor fed diesel usually stops, since it will not run, and the damage stops there. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump grinds. Being able to run is not proof of being fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old fix for a distinct problem. None of what petrol weakened is put back by it — and afterwards, that tank still contains that petrol.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the fuel filter and lines, ready to go right back through your pump at the next start. Also, a can of petrol drained by the roadside is genuinely hazardous.
Petrol in a diesel: how does it occur?
No one does it on purpose, and it is rarely carelessness. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol motor at all. The forecourt makes it simple, and the slip runs one way.
When routine and the car stop matching, it occurs. Hire cars, courtesy cars, and motors that are new to you. Two motors on one driveway, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. Filling up in a rush en route to South Merton, with a train to catch. Precisely the moment it takes place: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
How to prevent petrol in a diesel on your next fill-up around Merton Park
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- The first fill in a strange car is the time to check your filler flap — inside it, or on the cap, many motors state the fuel they take.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, for a household with one of each.
- It sounds daft and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Put your phone away. This is an easy mistake to make while you're thinking about something else.
- Add-on devices exist for cars without one, and some diesels come with a filler that won't take a petrol nozzle. Helpful — but a safety net only, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol in the tank means a thinner mix. What to do next doesn't change, though — still don't start the car.
Put petrol in a diesel in Merton Park already?
The order of things is short, then. Do not turn your ignition on, and do not crank it. Ask the attendants to help you push it clear of the pump if you're still at the forecourt, whether that is Esso or somewhere else. What was put in, about how much, and if it has run: tell us that when you phone 0333 366 0103.
Corrosion and deposits form the problem with AdBlue, where petrol brings lost lubrication. So if it was AdBlue, say so — and see its own Merton Park page.
Merton Park petrol in a diesel jobs: why one costs more than another
Four different jobs lie behind the four situations above — which is why there is no honest single quote. What moves your cost is chiefly which of them you are in. The proportion matters next, meaning how much of that tank is petrol, followed by the position of your car and whether reaching it is safe for a technician.
Three queries come first, before quoting, instead of after — what was put in, how much, has it run — and that is the reason. Their answers are what change a range into one firm number.
About Merton Park itself
Merton Park is a suburban area in southwest London, situated approximately 7 miles from the city centre. Merton Park has a relatively low elevation of 19 metres and is characterised by its predominantly terraced housing stock. Merton Park is located near other residential areas such as South Wimbledon and Wimbledon, and is part of the wider Merton borough.
Fuel drain cover in Merton Park and across Greater London
Our teams answering petrol in diesel jobs around Merton Park, in the SW postcode area, also work the spots around it, South Wimbledon, Wimbledon and Merton included. We drain wherever your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Still at the pump in Merton Park?
The best position there is, then — that's where you are. Phone, and leave it switched off.