How Worried Should You Be? Petrol in a Diesel Car in West Mersea
Far less than you likely are, provided it hasn't been started. Everyone around West Mersea starts with "have I wrecked it?", and the fair answer is usually no: petrol resting in your tank of any diesel stays harmless until priming, cranking or driving pulls it into your fuel system. Petrol in Diesel is who to phone, with your motor kept off, and so it remains that way. What petrol actually does to a diesel, how to gauge how far it has gone, and how to keep it from happening a second time: that is the remainder of this page.
Inside the engine: what petrol in a diesel does
Diesel has two tasks on its way through an engine. Oiling comes before burning; it does both. Made to very fine gaps, the fuel injectors and your pump depend on the diesel moving through them to stop their surfaces wearing against one another.
Of these two tasks, petrol handles the first badly and the second never. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the protection the fuel system depends on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where the knocking starts.
Put those together and the shape of the problem is clear. It's circulation that does the harm, not contact. All a tank with petrol in it amounts to is a fuel issue. Once the pump has been running on that petrol, a mechanical fault has begun: whatever is shed by a pump that is wearing down is carried downstream to the injectors with the fuel.
Petrol in a diesel around West Mersea: 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 task is clearing the tank and cleaning the fuel system where the vehicle stands. This situation can only really occur at a forecourt: anywhere else, the car got there by being driven.
Your ignition switched on, or a short start. With the system primed, your lines and filter now contain petrol that came from your tank. Drain, flush, deal with the fuel filter: still usually simple.
Some miles driven, and the pump has spent each of them running on diluted fuel. Tank, lines, filter, then fresh fuel run through the entire system: that is the work, and the way the car was driven matters as much as the mileage. Short trips, like the school run to Mersea Island School, are one matter. Any mileage on the M25, under 50 miles from West Mersea, means your engine has worked hard throughout, and a run to Colchester, under 10 miles away, makes a very different job too.
Driven till it protested. Knocking, an uneven idle, smoke, a throttle that has gone soft. What you are hearing is your motor signalling fuel that no longer runs like diesel. Stop on the spot — on the verge on High Street, at the kerb, down a side road — and don't move it. Lasting damage is very rare when a car is pulled over soon, and the fuel drain and flush-through that still come first take care of it.
Myths West Mersea motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. A fuller tank of the same mix is all you get, because topping up removes nothing. The idea behind the advice — that diesel fuel systems accept petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. Smaller components and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, so there is no harm" — the myth that catches more motorists than any other. Diesel in a petrol motor normally means a motor that will not run: the driver stops, and so does the damage. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, while the pump grinds. Being able to run isn't the same as being fine.
An old fix for a different issue lies behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside your tank after that, and whatever it has diluted isn't put back.
If your engine has been run, part of that petrol is in your filter and the fuel lines, not that tank — and the next start sends it right back through the pump. So the myth "drain the tank yourself and you're sorted" doesn't stand up. It's also really hazardous to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
No one does it on purpose, and it's rarely carelessness. The petrol nozzle is the narrower of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly will not go into a petrol car at all. The forecourt makes it simple, and the mistake runs one way.
The moment habit stops matching the car is the moment it occurs. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. A train to catch, and a rushed fill en route to Wivenhoe. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it occurs. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Avoiding petrol in a diesel next time you fill up around West Mersea
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Check the petrol pump's label; the colour is just a clue.
- Inspect the filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in a vehicle you don't know.
- Mark the key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away and keep your mind on the pump.
- Add-on devices exist for motors without one, and some diesels are built with a filler that won't take a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol inside the tank makes a thinner blend. What to do next does not change, though — still do not crank it.
West Mersea: already put petrol in a diesel?
The order of things is brief, then. Don't start it, and don't turn your ignition on. The staff on the forecourt — whether at Old Forge Filling Station itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. What was put in, about how much, and if it's run: tell us that when you phone 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a separate problem, with its own page for West Mersea, because AdBlue brings corrosion and deposits instead of lost lubrication.
Why one petrol in a diesel job in West Mersea costs more than another
The four scenarios above are four different tasks, so no single quote for this would be fair. The scenario itself does most of the work of moving the cost. Where your car is matters too, and whether a technician can safely reach it, after the ratio of petrol to what the tank holds.
Ahead of any quote, not after, we ask three questions: your fuel that went in, its amount, and if it's run. That is why. Their replies are what change a range into one firm number.
About West Mersea and its setting
West Mersea is a coastal town in Essex, situated on the Mersea Island, with an elevation of around 17 metres above sea level. West Mersea lies off the coast of mainland Essex, near the city of Colchester, and is connected to the mainland by a causeway. West Mersea is characterized by its predominantly detached housing stock and its proximity to nearby places such as Barrow Hill and Peldon. West Mersea has a population of approximately 6788 residents.
Fuel drain cover around West Mersea and across Essex
Our teams answering petrol in diesel calls around West Mersea, in the CO postcode area, equally work the places near it, Barrow Hill, Peldon and Downhall Beach Estate included. Our technicians drain where your vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the pump around West Mersea, right now?
No position is better: that's where you are. Keep the car turned off, and ring.