Firgrove: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as nobody has started the vehicle. Until the ignition primes your pump, your starter turns, or the car is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the honest reply to the first Firgrove question — "have I ruined it?" — normally no. Petrol in Diesel is who to phone, with the motor left off, so it stays that way. The remainder of this page sets out what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
The motor and petrol in a diesel: what goes on
Diesel does two tasks on its way through a motor. It combusts, and before it combusts it protects. The high-pressure pump and the injectors are made to extremely fine tolerances, and your diesel passing through them is what keeps those surfaces from wearing down against one another.
Of these two tasks, petrol manages the first badly and the second never. It's thinner than diesel and takes away the lubrication the 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 opposite of what a diesel needs from its fuel. That's where the rattling comes from.
Combined, those leave the shape of the problem plain. The harm is done by movement, not by contact. Where the petrol is only inside that tank, it's an issue of fuel, nothing more. Whatever a worn pump sheds travels on, carried by the fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical issue starts.
How serious is petrol in a diesel? Four situations our engineers see in Firgrove
Fuelled but not once started — the best it gets. Being at 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 emptied and flushed right where it stands, and nothing more is needed.
Started for a second, or only your ignition on. With the system primed, the fuel lines and filter already contain petrol that has come from that tank. Still normally straightforward: drain, flush, and the fuel filter seen to.
A few miles driven, and the pump has spent each of them labouring on weakened fuel. Tank, lines, filter, then clean fuel put through the entire circuit: that's the work, and the way the car was driven counts as much as the mileage. Short trips, like the school run to Moorhouse Academy, are one thing. Very different a second time: a run to Manchester, under 15 miles away, or some distance on the M62, under a mile from Firgrove, where your engine kept running hard.
Driven on till it protested — knocking, smoke, a lumpy idle, a dead throttle. The engine is telling you the fuel is no longer acting like diesel. Whether it's the verge on Willows Lane, a lay-by or a side road, stop where you are and leave it. Permanent damage is very unusual if a vehicle is stopped soon, and the fuel drain and flush that still come first take care of it.
Firgrove drivers and the petrol in a diesel myths they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. A bigger tank of the same mixture is all it gives, since topping up takes out nothing. Percentage isn't how a diesel fuel system tolerates petrol, however much that advice assumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise parts: that's how a current diesel handles its fuel, and so the lubrication counts more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it normally won't run, and so the motorist stops — and the damage stops with them. While the pump wears, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Fine and running are not the same at all.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, meant for another problem. What petrol has thinned remains diluted, and that petrol stays inside the tank anyway.
Once the motor has run, part of the petrol sits in your filter and the lines, not that tank — and the next start sends it right back through the pump. So the myth "drain the tank yourself and you are sorted" doesn't hold. Emptying petrol into a can at the kerbside is also genuinely risky.
Petrol in a diesel: how does it take place?
Nobody does it on purpose, and it is seldom carelessness. One way only, since of the nozzles: the slimmer petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol motor. That is how the forecourt makes it simple.
When routine and the vehicle stop matching, it takes place. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. The pumps in a different order on a familiar forecourt. A train to catch, and a hurried fill en route to Rochdale. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Throw in rain, a phone call or a back seat full of kids, and the hand does what it has always done.
Firgrove drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is only a clue.
- In a motor you do not know, look inside the flap over the filler or at the cap before the first fill: many motors print the fuel there.
- Label your 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.
- It seems daft and it works: on the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- Add-on devices are available for motors without one, and some diesels are built with a filler that won't accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Noticing it halfway? Stop at once. A weaker mixture results from less petrol inside the tank, but your next step remains the same: don't start it.
Firgrove: already put petrol in a diesel?
Then the order of things is short. Leave it unstarted, with the ignition switched off as well. Ask the attendants to help you push it clear of the petrol pump if you're still on the forecourt, whether that's Morrisons or anywhere else. What was put in, about how much, and whether it's run: tell us those when you call 0333 366 0103.
Say so if it was AdBlue instead of petrol: it is a separate issue, with its own page for Firgrove, since AdBlue brings corrosion and deposits rather than lost lubrication.
Firgrove petrol in a diesel jobs: why one costs more than another
The four situations above are four separate tasks, so no single quote for this would be honest. Which of them you are in is chiefly what moves the cost. After that it is the share — how much petrol went in against how much the tank takes — and then where the vehicle is and whether our van can get to it safely.
Before any quote, not after, we ask three questions: the fuel that got in, its volume, and if it's run. That's why. Those answers are what change a range into one firm number.
About Firgrove itself
Firgrove is a suburban area in Greater Manchester, situated near the River Roch and close to the towns of Newbold and Milnrow. Firgrove sits at an elevation of 152 metres, with semi-detached housing being the predominant type of accommodation. Firgrove is located approximately 10.5 miles from Manchester, making it a commuter-friendly area. Firgrove has a population of around 4132 residents.
Firgrove and Greater Manchester: where our fuel drain cover reaches
The vans answering petrol in diesel calls in Firgrove, in the OL postcode area, equally work the places near it, Newbold, Milnrow and Belfield included. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations we drain.
At the petrol pump in Firgrove, still?
Then you are in the best position there can be. Ring, and keep it turned off.