Faldingworth: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as no one has started it. Everyone in Faldingworth starts with "have I wrecked it?", and the honest answer is generally no: petrol resting in your tank of any diesel remains harmless until priming, cranking or driving draws it into the system. Petrol in Diesel is who to ring, with the engine kept off, and so it remains that way. Further down, you will find what petrol actually does inside a diesel, how far it may have gone, and how to stop it happening to you again.
What petrol in a diesel does to the engine
Passing through a motor, diesel does two things at once. It protects first, and only then does it burn. What stops the surfaces inside your high-pressure pump and the injectors from wearing down against one another is the diesel flowing through them — they're made to extremely fine gaps.
Of these two jobs, petrol handles the first poorly and the second never. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump on the mixture to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
The shape of the trouble is clear when you put those together. Contact does not do the damage — circulation does. All a tank with petrol in it amounts to is a fuel issue. After your pump has been labouring on that petrol, a mechanical problem has started: whatever is shed by a pump that is wearing travels downstream to your injectors with the fuel.
Four scenarios our technicians see around Faldingworth: how bad is petrol in a diesel?
Filled but never started — as good as it gets. The petrol is inside that tank and just the tank, and the job is a drain and a flush where your car sits. This is the one situation that can only really occur on a forecourt, because anywhere else the vehicle has been driven to get there.
A moment's running, or just the ignition on. Petrol has left your tank and reached the filter and the lines, since the system has been bled. Normally nothing more than emptying, purging and seeing to your filter, and so still straightforward.
Those few miles driven were the pump labouring on fuel thinned by petrol throughout. The work is that tank, the fuel lines, the fuel filter and clean fuel through the whole circuit, and how hard your car was driven counts as much as how far. Driving the kids to Faldingworth Community Primary School is one sort of trip. Driving as far as Lincoln, under 10 miles away, makes a very different task — as does any distance on the M180, under 15 miles from Faldingworth, with your engine running hard all the way.
Clattering, an uneven idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is your motor reporting fuel that no longer behaves like diesel. Stop wherever you are — the verge on Stocks Lane, a lay-by, a side street — and leave the vehicle where it is. The drain and flush still go first, and they take care of it: if a car is stopped early, permanent damage is very rare.
What Faldingworth people get told about petrol in a diesel — and the stories in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. The idea behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Not so: a newer diesel copes with a bit of petrol. If anything, the reverse. A current diesel sends its fuel through more precise parts at higher pressure, which makes the protection matter more, not less.
One myth that catches drivers off guard: if it starts and drives, it must be unharmed. Any petrol engine fed diesel usually won't run, and so the motorist stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile your pump grinds. A running engine doesn't mean fine.
An outdated fix for a distinct fault lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." It doesn't put back what petrol has diluted, and the petrol is still in the tank afterwards.
Myth: "Drain that tank yourself and you are sorted." After the engine has run, some of the petrol is no longer inside the tank: it's in your filter and your lines, and it goes right back through the pump on the next start. It is also truly dangerous to drain petrol into a can by the kerbside.
How it happens: petrol in a diesel
It is rarely carelessness, and no one does it on purpose. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol car. That's how the forecourt makes it simple.
It takes place when habit and the car stop matching. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. A forecourt you know, but with its pumps laid out differently. Filling up in a rush en route to Market Rasen, with a train to catch. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Your hand repeats what it has always done once you add rain, a phone call or a back seat full of kids.
Preventing petrol in a diesel next time you fill up in Faldingworth
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Go by the label on the pump, not the colour.
- Inspect your filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a motor you do not know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key if a household has one of each. So mark it.
- Before the nozzle comes off the pump the first time you fill a hired or new motor, say "diesel" out loud. Silly, yes, yet it does the trick.
- Put the phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- Noticing it mid-fill? Stop at once. A thinner blend results from less petrol in that tank, but the next step remains the same: do not start the car.
Faldingworth: already put petrol in a diesel?
The order of things is brief, then. Don't switch the ignition on, and do not start it. Yet on the forecourt, at Tesco or anywhere else? Ask the attendants to help you push the car away from the pump. What got in, about how much, and if it has run: tell us those when you call 0333 366 0103.
If it was AdBlue instead of petrol, say so. That's a separate problem — corrosion and deposits and not lost lubrication — and it has its own page for Faldingworth.
One petrol in a diesel task in Faldingworth costs more than another. Why?
Four separate tasks sit behind the four situations above — which is why there's no honest single quote. What shifts your cost is chiefly which of them you're in. Where the car is matters too, and whether our van can safely get to it, after the proportion of petrol to what your tank holds.
That is why our technicians ask three questions before quoting instead of after: what got in, how much, and if it has run. The answers turn a range into a straight figure.
About Faldingworth and where it is
Faldingworth is a small village in Lincolnshire, situated near the River Trent at an elevation of around 26 metres. Faldingworth lies close to the cities of Lincoln and is surrounded by other villages such as Friesthorpe and Buslingthorpe. Faldingworth has a population of approximately 505 people and predominantly consists of detached housing. Faldingworth is located about 127.7 miles north of London, making it a relatively rural community.
Fuel drain cover in Faldingworth and across Lincolnshire
Petrol in diesel call-outs around Faldingworth — part of the LN postcode area — go to vans that likewise cover the locations round it, Friesthorpe, Buslingthorpe and Newtoft included. The car doesn't need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the pump in Faldingworth, still?
Then you are in the best position there is. Switched off it remains; then ring.