Petrol in a Diesel Car in Rainham: How Worried Should You Be?
Likely less than you are now — as long as no one has started the vehicle. Until your ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does nothing. Which means the truthful reply to the first Rainham question — "have I ruined it?" — usually no. To leave the car that way, ring Petrol in Diesel then leave your motor alone. Further down, this page sets out what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you again.
Inside the engine: what petrol in a diesel does
Passing through a motor, diesel does two jobs at the same time. Oiling comes before burning; it does both. The high-pressure fuel pump and your injectors are designed to very fine tolerances, and your diesel passing through them is what keeps those surfaces from grinding against each other.
Poorly at the first, not at all at the second: that is petrol. It's runnier than diesel and strips away the lubrication your fuel system hinges on, so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from.
Seen together, they make clear what shape the trouble has. Contact does not do the harm — circulation does. Petrol in the tank is a fuel problem. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors further on.
Four scenarios our engineers see around Rainham: how bad is petrol in a diesel?
Filled but not once started — as good as it gets. That petrol is inside that tank and just your tank, and the job is a drain and a flush where the car sits. This is the one scenario that can only truly occur on a forecourt, since anywhere else the vehicle has been driven to get there.
Ignition on, or started for a moment. With the fuel system primed, the lines and filter now hold petrol that came from the tank. That's usually still an easy job — a drain, a flush, and your filter seen to.
Some miles driven, and your pump has spent each of them labouring on thinned fuel. Tank, lines, filter, then clean fuel put through the entire system: that is the work, and the way your car was driven counts as much as the mileage. On the school run to Rainham Village Primary School, the mileage is short. A run as far as London, under 15 miles away, is a very different task. So is any distance on the M25, under 5 miles from Rainham, where the engine has been running hard the whole time.
Driven on till it protested — clattering, smoke, an uneven idle, a dead throttle. The fuel is not behaving like diesel any more, and the motor is saying so. Pull up on the spot — on the verge on Broadway, at the kerb, down a side road — and don't move it again. Long-term damage is very unusual when a vehicle is stopped soon, and the drain and flush that still come first deal with it.
What Rainham people get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Myth: a modern diesel copes with a bit of petrol. If anything, the reverse. Finer 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 there is no harm" — the myth that trips up more motorists than any other. Any petrol engine fed diesel normally won't run, and so the motorist stops and the damage stops with them. While your pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated workaround for a different issue. What petrol has weakened stays diluted, and the petrol stays inside the tank anyway.
If your engine has been run, part of that petrol sits in your filter and your lines, not your tank — and the next start sends it straight back through your pump. So the myth "drain your tank yourself and you are sorted" doesn't stand up. It's also really hazardous to drain petrol into a can at the kerbside.
How does petrol in a diesel occur?
A careless moment is rarely the cause, and no one means to do it. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol motor. That's how the forecourt makes it simple.
The moment routine stops matching the vehicle is the moment it occurs. Hire cars, courtesy cars, and cars that are new to you. Two cars on one drive, one petrol, one diesel. A forecourt you know, but with its pumps laid out differently. Racing for a train at Rainham (Essex) and filling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a driver used to petrol: exactly when it occurs. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
How to prevent petrol in a diesel at your next fill-up in Rainham
- A green handle for unleaded and black for diesel is usual in the UK — but not on every forecourt. Trust the label on the pump, not the colour.
- In a car you don't know, look inside the flap over your filler or at the cap before your first fill: plenty of vehicles print the fuel there.
- Label the 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 meaning to remember.
- It sounds silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to block a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop checking the pump.
- Stop as soon as you notice. Less petrol inside the tank makes a thinner blend. It doesn't change what to do next, which is still not to start the vehicle.
Put petrol in a diesel in Rainham already?
Then the order of things is brief. Leave it unstarted, with the ignition off as well. The staff at the forecourt — whether at the nearest petrol station itself or wherever you filled up — will usually help push it clear of the petrol pump if you ask. What was put in, roughly how much, and whether it has run: tell us those when you phone 0333 366 0103.
If it was AdBlue instead of petrol, say so. That is a different fault — corrosion and deposits rather than lost protection — and it has its own page for Rainham.
What makes one Rainham petrol in a diesel job cost more than the next
The four scenarios above are four different tasks, so no single quote for this would be fair. Which of them you are in is chiefly what moves your cost. Two things come after that: the petrol that got in as a share of what that tank holds, then the place the car is in and whether a technician can reach it safely.
Before any quote, not after, we ask three queries: your fuel that went in, the amount, and if it has run. That's why. The answers turn a range into a straight figure.
About Rainham and its setting
Rainham is a locality in east London, situated on the north bank of the River Thames at a low elevation of around 5 metres. Rainham lies within the Greater London area, approximately 13.7 miles from central London, and is near the communities of South Hornchurch, Wennington, and Dagenham. Rainham is characterized by its predominantly flat housing stock, reflecting its urban setting.
Fuel drain cover across Greater London, Rainham included
Our vans answering petrol in diesel jobs around Rainham, in the RM postcode area, also work the spots near it, South Hornchurch, Wennington and Dagenham included. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots where we work.
In Rainham and still at the pump?
In that case, you couldn't be in a better spot. Ring, and leave it turned off.