Should You Worry? Petrol in a Diesel Car in Merryhill Green
Less than you probably are, if it hasn't been started. Petrol resting in a diesel tank does nothing to your engine until something draws it through the system — the ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first question everyone around Merryhill Green asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to phone, with the engine left off, so it stays that way. Keep reading for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and the way to make sure you never do it again.
The engine and petrol in a diesel: what happens
On its way through a motor, diesel does two tasks. Oiling comes before burning; it does both. Built to extremely fine tolerances, the fuel injectors and your pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that's petrol. It's runnier than diesel and removes the protection the system hinges on, so a pump running on a petrol mix 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 rattling comes from.
Put these together and the shape of the problem is plain. The harm is done by circulation, not by contact. All a tank with petrol in it amounts to is a fuel fault. Once the pump has been running on that petrol, a mechanical fault has started: whatever is shed by a pump that's grinding is carried downstream to your injectors with your fuel.
Four situations our technicians see around Merryhill Green: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there is. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With that petrol held inside that tank alone, it is cleared and rinsed right where it stands, and nothing more is needed.
A moment's running, or merely the ignition on. Once primed, the fuel system has pulled petrol from that tank as far as the fuel filter and the fuel lines. That is normally still a simple job — a drain, a flush, and your filter dealt with.
Your pump now worked a few miles on diluted fuel — that's what driving the vehicle does. How hard your car was driven matters as much as how far, and the work takes in that tank, the fuel lines, the fuel filter and clean fuel through the entire circuit. A school run to Winnersh Primary School is one matter. Any mileage on the A329(M), under a mile from Merryhill Green, means the motor has worked hard throughout, and a run to Oxford, under 50 miles away, is a very different job as well.
Driven on until it complained — knocking, smoke, a lumpy idle, a dead throttle. What you are hearing is your engine signalling fuel that no longer acts like diesel. Whether it is the verge on Meadow View, a lay-by or a side street, stop there then leave it. A vehicle stopped soon very rarely has permanent damage, as the fuel drain and the flush-through, which still go first, sort it out.
What Merryhill Green people get told about petrol in a diesel — and the stories in it
False: topping up to full with diesel makes it fine. It does not. Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. A diesel fuel system does not tolerate petrol by percentage in the way that advice assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Lubrication matters more on modern diesels, not less, because their fuel passes through smaller components at higher pressure.
The myth that catches drivers off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that won't run: the motorist stops, and so does the damage. Whilst your pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an outdated workaround for a separate problem. None of what petrol weakened gets put back by it — and afterwards, that tank still contains that petrol.
The next start draws petrol back round the pump from your lines and the fuel filter, where some of it sits once the motor has been run. That's why a DIY tank drain does not leave you sorted — a myth. And, a can of petrol filled by the kerbside is genuinely hazardous.
Why petrol in a diesel happens at all
It's rarely carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol car at all. So the error runs one way.
The moment routine stops matching your car is the moment it happens. A new motor, a hire car or a courtesy car. A household with one petrol and one diesel on the driveway. Your usual forecourt, its pumps suddenly in a different order. Racing for a train at Winnersh and fuelling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist used to petrol: exactly when it takes place. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
Merryhill Green people: how to avoid petrol in a diesel next time
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- Check your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on your first fill in a vehicle you don't know.
- Label the key. In a home with one of each, a coloured fob or a sticker on your 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 pump. It sounds silly and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck your phone away and keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to refuse a petrol nozzle, and add-on devices exist for the rest. Treat it as a safety net, and keep checking the pump.
- Spotting it halfway? Stop at once. A weaker mixture results from less petrol in the tank, yet your next step remains the same: do not crank it.
Petrol already in a diesel in Merryhill Green? Start here
Then the order of things is short. Don't turn your ignition on, and don't start it. Yet at the forecourt, at BP or anywhere else? Ask the staff to help you push it away from the petrol pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it has been run.
Say so if it was AdBlue rather than petrol: it is a different issue, with its own page for Merryhill Green, because AdBlue brings corrosion and deposits rather than lost protection.
Merryhill Green petrol in a diesel tasks: why one costs more than another
A fair single price doesn't exist here: four scenarios, four separate jobs. Which of them you are in is mostly what moves your cost. Two things follow that: the petrol that got in as a proportion of what that tank holds, then the spot the car is in and whether our van can get to it safely.
What got in, how much, and whether it's run — three queries our engineers ask before costing, not after, for exactly that reason. A range turns into a straight figure once the answers are in.
About Merryhill Green itself
Merryhill Green is a suburban area in Berkshire, situated near the River Loddon and close to the villages of Winnersh and Sindlesham. Merryhill Green has a relatively low elevation of 41 metres and is located near the town of Wokingham, with easy access to the nearby city of Oxford. Merryhill Green is characterized by its predominantly detached housing stock, reflecting its suburban nature.
Fuel drain cover around Merryhill Green and across Berkshire
Winnersh, Emmbrook and Sindlesham are among the places near Merryhill Green that the same vans work, answering petrol in diesel call-outs across Merryhill Green's RG postcode area. The car does not need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump around Merryhill Green?
Then you're in the best spot there is. Keep it off. Phone.