Hill Hook: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — provided nobody has started the vehicle. Till your ignition primes the pump, the starter cranks, or your car is driven, petrol in a diesel tank just sits there and does nothing. Which means the truthful reply to that first Hill Hook question — "have I wrecked it?" — usually no. Petrol in Diesel is who to call, with the motor kept off, so it stays that way. Further down, 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 your engine: what petrol in a diesel really does
Passing through an engine, diesel is doing two jobs at once. Lubricating comes before burning; it does both. Extremely fine tolerances go into the fuel injectors and the high-pressure pump, and only your diesel flowing through keeps their surfaces from grinding together.
Of those two jobs, petrol manages the first badly and the second never. A pump running on a petrol mixture is wearing itself out, since petrol is runnier than diesel and strips out the lubrication your fuel system depends on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where any knocking comes.
Taken together, they make clear the shape the issue has. The harm is done by movement, not by contact. A tank with petrol in it is a fuel issue. The beginning of a mechanical problem is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
Four situations we see around Hill Hook: how bad is petrol in a diesel?
Filled but not once started — the best it gets. That petrol is in your tank and only the tank, and the task is a drain and a flush where the car sits. This is the one scenario that can only really take place on a forecourt, as anywhere else the vehicle has been driven to get there.
Ignition on, or started for a moment. The system has been primed, so petrol has left that tank and reached the filter and your lines. Usually little more than draining, rinsing and sorting your filter, so still straightforward.
Those few miles driven meant the pump working on fuel diluted by petrol throughout. The work is your tank, the lines, your filter and fresh fuel through the whole circuit, and how hard the vehicle was driven counts as much as how far. On the school run to Four Oaks Primary School, the miles is short. Driving as far as Lichfield, under 10 miles away, makes a very different job — as does any distance on the M6 Toll, under 3 miles from Hill Hook, with the engine running hard all the way.
Driven on until it protested — rattling, smoke, an uneven idle, a soft throttle. That's the motor telling you its fuel has stopped behaving like diesel. Whether it is the verge on Clarence Road, a lay-by or a side street, stop there and leave it. The fuel drain and flush-through still come first, and they take care of it: if a car is pulled over early, permanent damage is very unusual.
Hill Hook drivers and that petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through smaller parts: that's how a current diesel moves its fuel, so the lubrication matters for more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. Feed diesel to a petrol motor and it usually will not run, so the motorist stops — and the harm stops with them. A diesel fed petrol generally starts, ticks over and drives away as if nothing has happened, whilst the pump wears. Running does not mean fine.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, supposed for another fault. None of what petrol thinned is put back by it — and later, the tank still contains the petrol.
Myth: "Drain your tank yourself and you're sorted." Once your engine has run, some of that petrol is no longer in the tank: it is in your filter and the lines, and it goes straight back through the pump on your next start. And, a can of petrol drained at the kerbside is truly risky.
Petrol in a diesel: how does it happen?
It's seldom carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
It occurs when routine and your car stop matching. A new car, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps laid out differently. Racing for a train outside Blake Street and fuelling up en route. Precisely the moment it happens: after years of driving petrol, someone fills a diesel Volkswagen Tiguan for the first time. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
How to avoid petrol in a diesel on your next fill-up around Hill Hook
- Green 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.
- Many cars state the fuel inside the filler flap or on the cap, so check there on the first fill in a vehicle you don't know.
- One of each in the home? Mark your key to your diesel — a bright fob, a sticker — because meaning to remember isn't enough.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car needs its first tank. It seems silly. It works.
- While you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels have a filler built to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop the moment you notice. Less petrol inside that tank makes a weaker mix. It doesn't change what to do next, which is still not to start the vehicle.
Already put petrol in a diesel in Hill Hook?
Short and simple, then, is the order of things. Do not start the vehicle, and don't switch your ignition on. The staff at the forecourt — whether at Shell itself or wherever you filled up — will normally help roll it clear of the petrol pump if you ask. What was put in, about how much, and whether it has run: tell us that when you phone 0333 366 0103.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Hill Hook, because AdBlue brings corrosion and deposits rather than lost protection.
One petrol in a diesel task around Hill Hook costs more than another. Why?
There is no fair single price for this, because the four scenarios above are four different jobs. Mostly, the cost moves with which situation you're in. The proportion counts next, meaning how much of the tank is petrol, followed by the location of your car and whether reaching it is safe for our van.
That's why our technicians ask three queries before pricing rather than after: what was put in, how much, and if it has run. The replies turn a range into a straight figure.
About Hill Hook and where it is
Hill Hook is a suburban area in the West Midlands, situated approximately 5.7 miles from Lichfield and 105.2 miles northwest of London. Hill Hook sits at an elevation of around 138 metres, characterised by its predominantly detached housing stock. Hill Hook is surrounded by nearby places such as Hill, Little Aston, and Four Oaks, and has a population of around 3872 residents.
Hill Hook and West Midlands: where our fuel drain cover runs
Hill, Little Aston and Four Oaks are among the spots near Hill Hook that the same vans work, answering petrol in diesel call-outs across Hill Hook's B postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all locations we work, and your car does not need to move to us.
Hill Hook: still at the pump?
The best spot there is, then — that's where you are. Keep the car turned off, then ring.