Petrol in a Diesel Car in Higher Denham: How Worried Should You Be?
Far less than you likely are, provided it hasn't been started. Everyone around Higher Denham starts with "have I wrecked it?", and the fair answer is generally no: petrol left inside that tank of any diesel stays harmless until priming, cranking or driving draws it into the fuel system. Keep it like that: leave your engine off and ring Petrol in Diesel. Below, this page sets out what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
Inside your engine: what petrol in a diesel really does
Two jobs fall to diesel on its route through a motor. It burns, and before it combusts it lubricates. Your high-pressure pump and the fuel injectors are made to very fine gaps, and the diesel passing through them is what stops those surfaces from wearing down against one another.
Poorly at the first, not at all at the second: that's petrol. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection your system depends on, and any pump working on such a blend is wearing itself.
Together, those leave the shape of the problem plain. Contact does not do the harm — movement does. A tank with petrol in it is a fuel fault. Once the pump has been labouring on that petrol, a mechanical fault has started: whatever is shed by a pump that's wearing down travels downstream to the fuel injectors with the fuel.
Four scenarios our technicians see around Higher Denham: how serious is petrol in a diesel?
Fuelled, and not started: nothing beats it. That petrol is in that tank and only the tank, and the job is a drain and a flush where the car sits. This is the one scenario that can only truly occur at a forecourt, because anywhere else the vehicle has been driven to get there.
Ignition on, or started for a moment. With the fuel system primed, the fuel lines and filter already contain petrol that came from the tank. Drain, flush, deal with the fuel filter: still normally easy.
Some miles driven, and your pump has spent each of them labouring on weakened fuel. Tank, lines, filter, then fresh fuel put through the entire system: that's the work, and the way the vehicle was driven counts as much as the miles. A school run to Denham Green E-ACT Primary Academy is one thing. Very different a second time: a trip to St Albans, under 15 miles away, or some distance on the M25, under a mile from Higher Denham, where your engine never stopped labouring hard.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven till it complained. The fuel isn't acting like diesel any more, and your engine is telling you. Whether it is the verge on Upper Road, a lay-by or a side street, stop there and leave it. Lasting damage is very uncommon if a vehicle is stopped quickly, and the fuel drain and flush that still come first take care of it.
Higher Denham drivers and that petrol in a diesel myths they hear
Myth: topping up to full with diesel makes it fine. It does not. A fuller tank of the same mix is all it gives, since topping up takes out nothing. That guidance presumes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that is how a modern diesel handles its fuel, so the protection matters more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it normally won't run, so the motorist stops — and the damage stops with them. A diesel fed petrol generally starts, ticks over and drives away as though nothing has happened, whilst your pump grinds. Running doesn't mean fine.
Not so: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another fault. It doesn't put back what petrol has thinned, and that petrol is still in that tank after that.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the filter and lines, waiting to go right back through the pump on the next start. Emptying petrol into a can at the kerbside is also really risky.
Petrol in a diesel: how does it happen?
A careless moment is seldom the cause, and no one means to do it. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle mostly won't go into a petrol vehicle at all. The forecourt makes it easy, and the slip runs one way.
Habit and the vehicle getting out of step is when it occurs. Hire cars, courtesy cars, and motors that are new to you. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. A train to catch, and a rushed fill on the way to Denham Golf Club. Precisely the moment it takes place: after years of driving petrol, a driver fills a diesel Skoda Octavia for the first time. The hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Higher Denham motorists: how to prevent petrol in a diesel next time
- Read the pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on every forecourt. The label is what counts.
- Many cars state the fuel inside your filler flap or on the cap, and so check there on the first fill in a motor you do not know.
- One of each in the household? Label your key to your diesel — a coloured fob, a sticker — because intending to remember is not enough.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Put your phone away. This is an easy mistake to make whilst you are thinking about something else.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the petrol pump.
- Spotting it halfway? Stop at once. A thinner mix follows from less petrol inside that tank, yet the next step stays the same: don't fire it up.
Already put petrol in a diesel around Higher Denham?
The order of things is brief, then. Don't fire it up, and don't switch the ignition on. Yet on the forecourt, at Shell or anywhere else? Ask the attendants to help you push the car away from the pump. Then phone 0333 366 0103 and tell us what got in, roughly how much, and if it has run.
If it was AdBlue instead of petrol, say so. That is a separate issue — corrosion and deposits rather than lost lubrication — and it has its own page for Higher Denham.
Higher Denham petrol in a diesel tasks: why one costs more than another
There's no honest single price for this, because the four situations above are four different tasks. What shifts the cost is chiefly which of them you're in. Where the vehicle is counts too, and whether a technician can safely get to it, after the proportion of petrol to what your tank holds.
Ahead of any quote, not after, come three queries: your fuel that was put in, the amount, and if it's run. That's why. With those answers, you get a straight figure instead of a range.
About Higher Denham
Higher Denham is a small village in Buckinghamshire, situated on the banks of the River Colne at an elevation of around 55 metres. Higher Denham lies within the South East region, approximately 17.5 miles from London and 14.1 miles from St Albans. Higher Denham has a mix of rural and suburban characteristics, with detached housing being the predominant type and nearby places including Bakers Wood, Tatling End, and Denham.
Across Buckinghamshire and in Higher Denham: fuel drain cover
Petrol in diesel call-outs in Higher Denham — part of the UB postcode area — go to vans that likewise cover the locations around it, Bakers Wood, Tatling End and Denham among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all places our technicians work, and your car doesn't need to come to us.
At the petrol pump around Higher Denham, still?
No position is better: that is where you now are. Phone, and leave it turned off.