California: Petrol in a Diesel Car? How Worried to Be
Provided it hasn't been started, you can worry less than you probably are. "Have I ruined it?" is the first thing anyone around California asks, and the truthful answer is generally no, since petrol left in a diesel tank harms nothing until it's drawn through the system — by ignition priming, by your starter, or by driving. To keep it like that, call Petrol in Diesel and leave the engine switched off. The remainder of this page sets out what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Inside the motor: what petrol in a diesel really does
Diesel does two tasks on its way through a motor. It ignites, and before it ignites it protects. The high-pressure pump and the fuel injectors are built to extremely fine clearances, and the diesel passing through them is what stops those surfaces from wearing down against one another.
Petrol does the first job badly and the second not at all. Being less viscous than diesel, petrol strips out the protection a fuel system needs, leaving a pump running on the blend wearing itself. It's also made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the rattling.
Seen together, they show what shape the trouble takes. It's circulation that causes the damage, not contact. Any tank with petrol in it is a fuel problem. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on.
California, petrol in a diesel: four situations, from mild to major
The best case there can be: filled up, not once started. Being on a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With that petrol kept inside the tank alone, it is cleared and flushed right where it stands, and nothing more is needed.
Ignition on, or started for a moment. Petrol has come out of that tank and got to the filter and the lines, because the fuel system has been bled. That's generally still a straightforward task — a drain, a flush, and the fuel filter seen to.
Those few miles on the road meant the pump running on fuel thinned by petrol the whole way. How hard the vehicle was driven counts as much as how far, and this work covers your tank, your lines, the filter and fresh fuel through the entire system. On the school run to Whale Hill Primary School, the distance is small. A run as far as Durham, under 25 miles away, is a very different job. So is any mileage on the A1(M), under 25 miles from California, where your engine has been working hard the whole time.
Driven until it complained. Clattering, a ragged idle, smoke, a throttle that has gone soft. The fuel is not acting like diesel any more, and your motor is saying so. Stop wherever you are — the verge on Cleveland Street, a lay-by, a side street — and leave the vehicle there. What goes first is still the fuel drain and flush, and that deals with it, with lasting damage very unusual when a vehicle is stopped soon.
What California people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing comes out when you top up — your tank just holds more of the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
If anything, the reverse is true. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through more precise components: that's how a newer diesel moves its fuel, so the lubrication matters more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools drivers. Feed diesel to a petrol motor and it usually won't run, and so the motorist stops — and the damage stops with them. A diesel fed petrol normally starts, ticks over and drives away as though nothing has happened, while your pump wears. A running engine doesn't mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated workaround for a separate problem. None of what petrol diluted is put back by it — and afterwards, the tank still holds that petrol.
Myth: "Drain that tank yourself and you are sorted." Once the engine has run, some of that petrol is no longer in that tank: it's in the filter and your lines, and it goes right back through your pump on the next start. It's also truly risky to drain petrol into a can at the kerbside.
Petrol in a diesel: how does it happen?
A careless moment is seldom the cause, and no one means to do it. One way only, since of the nozzles: the smaller 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.
It happens when routine and the car stop matching. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps arranged differently. Filling up in a hurry on the way to South Bank, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Next time you fill up around California: avoiding petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Read the petrol pump's label; the colour is only a hint.
- In a car you don't know, look inside the flap over the filler or at the cap before your first fill: plenty of motors state the fuel type 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.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for cars without one. They are a safety net, not a reason to stop checking the petrol pump.
- Noticing it halfway? Stop there and then. A thinner blend follows from less petrol in your tank, yet your next step remains the same: do not crank it.
Already put petrol in a diesel around California?
In that case, there is just a short order of things. Starting it is out, and so is switching on your ignition. Still at the forecourt, at Shell or anywhere else? Ask the staff to help you roll the vehicle clear of the petrol pump. Call 0333 366 0103 next, with three answers — your fuel, the rough volume, and whether it's run.
Say so if it was AdBlue instead of petrol: it is a different fault, with its own page for California, since AdBlue brings corrosion and deposits rather than lost protection.
California petrol in a diesel tasks: why one costs more than another
The four situations above are four separate jobs, so no single price for this would be fair. Which of them you are in is chiefly what moves your cost. Where the vehicle is matters too, and whether a technician can safely reach it, after the proportion of petrol to what your tank takes.
That's why we ask three queries before costing rather than after: what went in, how much, and whether it's run. Their replies are what change a range into one firm number.
About California, for a moment
California is a suburban area in North Yorkshire, situated on the riverside at an elevation of 48 metres. California is located near the towns of Eston, Lackenby, and Normanby, and is approximately 23 miles from the city of Durham. California has a population of around 6090 people, predominantly living in semi-detached housing. California is also relatively distant from London, at a distance of 215 miles.
California and North Yorkshire: where our fuel drain cover reaches
Eston, Lackenby and Normanby are among the spots near California that the same vans work, answering petrol in diesel jobs across California's TS postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians drain, and the car does not need to move to us.
At the pump around California, still?
The best position there is, then — that is where you are. Phone, and leave it switched off.