Should You Worry? Petrol in a Diesel Car in Cookshill
Less than you likely are, provided it hasn't been started. Till your ignition primes the pump, the starter turns, or your car is driven, petrol in a diesel tank just sits there and does no harm. Which makes the truthful reply to that first Cookshill query — "have I ruined it?" — normally no. Petrol in Diesel is who to phone, with your engine kept off, and so it stays that way. 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 does
Diesel has two tasks on its way through a motor. Before it combusts, it protects — and then it combusts. The high-pressure pump and the injectors are built to very fine tolerances, and the diesel passing through them is what stops those surfaces from wearing down against each other.
The second job petrol does not do at all, and the first it does badly. The knocking comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection your system hinges on, and any pump running on such a mix is wearing itself.
Seen together, they make clear what shape the issue takes. The damage is done by circulation, not by contact. Petrol in the tank is a fuel issue. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors beyond it.
Petrol in a diesel around Cookshill: how serious is it? Four cases
Fuelled, and not started: no case is better. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept inside your tank alone, it is drained and purged right where it stands, and nothing more is needed.
Ignition on, or started for a second. Petrol has left that tank and reached the fuel filter and the fuel lines, because the fuel system has been bled. Usually little more than emptying, cleaning and seeing to the fuel filter, and so still straightforward.
Those few miles on the road meant your pump working on fuel thinned by petrol the whole way. Mileage is only half of it; how hard it was driven counts equally. Either way the work includes your tank, the fuel lines, the filter and clean fuel through the entire circuit. The school run to St Peter's Church of England Primary School is one thing. Driving as far as Stoke-on-Trent, under 5 miles away, makes a very different job — as does any mileage on the M6, under 10 miles from Cookshill, with the engine running hard all the way.
Driven till it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. What you are hearing is your engine signalling fuel that no longer behaves like diesel. Stop where you are — on the verge on The Green, at the kerb, down a side road — and don't move it. A car stopped soon very seldom has permanent damage, as the fuel drain and the flush-through, which still go first, sort it out.
Petrol in a diesel myths Cookshill motorists hear
Myth: topping up to full with diesel makes it fine. It does not. A bigger tank of the same mix is all you get, because topping up removes nothing. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a newer diesel copes with a bit of petrol. If anything, the opposite. More precise components and higher pressure are the way a current diesel runs its fuel, and that makes the lubrication count more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools motorists. Any petrol engine fed diesel normally will not run, and so the motorist stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile your pump grinds. A running engine doesn't mean fine.
An outdated workaround for a different issue is behind this one. Myth: "Add some two-stroke oil and drive it home." It does not put back what petrol has weakened, and the petrol is still inside that tank after that.
"Drain it yourself and you're sorted" — a myth, because after it has been running some petrol sits in the filter and lines, waiting to go right back through your pump on the next start. Besides, petrol drained into a can by the road is genuinely risky.
How does petrol in a diesel happen?
A careless moment is seldom the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol vehicle at all. So the slip runs one way.
When habit and the car stop matching, it happens. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the drive. Your ordinary forecourt, its pumps suddenly in a different order. A hurried fill on the way to Blythe Bridge with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a driver used to petrol: exactly when it occurs. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
Avoiding petrol in a diesel next time you fill up in Cookshill
- Green for unleaded and black for diesel is normal in the UK — but not on every forecourt. Trust the label on the petrol pump, not the colour.
- In a car you don't know, look inside the flap over the filler or at the cap before your first fill: many motors print the fuel there.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, in a household with one of each.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Mistakes like this are easy to make while your mind is on something else, and so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices are available for the rest. Count it as a safety net, and keep checking the pump.
- The moment you realise, stop: less petrol in your tank means a weaker mix. What to do next does not change, though — still don't start the vehicle.
Petrol already in a diesel in Cookshill? Begin here
The order of things is short, then. Starting it is out, and so is turning on your ignition. Ask the staff to help you roll it clear of the pump if you're still at the forecourt, whether that's BP or somewhere else. What got in, about how much, and if it's run: tell us that when you call 0333 366 0103.
Say so if it was AdBlue instead of petrol: it is a different issue, with its own page for Cookshill, because AdBlue brings corrosion and deposits rather than lost lubrication.
One petrol in a diesel task around Cookshill costs more than another. Why?
The four situations above are four different jobs, so no single price for this would be honest. Which of them you're in is chiefly what moves your cost. Next it is the share — how much petrol was put in against how much that tank holds — and then where the vehicle is and whether our van can get to it safely.
That is why our technicians ask three queries before pricing rather than after: what went in, how much, and if it has run. Those replies turn a range into a straight figure.
About Cookshill itself
Cookshill is a small village in Staffordshire, situated on the riverside at an elevation of 196 metres, with semi-detached housing being the predominant type of accommodation. Cookshill lies close to the city of Stoke-on-Trent, approximately 4.5 miles away, and is near other villages such as Caverswall and Weston Coyney. Cookshill has a population of around 618 people and is located in a rural area, with the nearest major city being Stoke-on-Trent. Cookshill is also relatively distant from London, at a distance of 131.5 miles.
Fuel drain cover across Staffordshire, Cookshill included
Cookshill sits in the ST postcode area, and our vans that answer petrol in diesel jobs there work the spots near it as well — Caverswall, Roughcote and Weston Coyney among them. The car doesn't need to move to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump around Cookshill?
No position is better: that's where you are. Turned off it remains; then call.