How Worried Should You Be? Petrol in a Diesel Car in Tarnock
Provided it hasn't been started, worry far less than you likely are. Until your ignition primes the pump, the starter cranks, or your car is driven, petrol in a diesel tank just sits there and does no harm. Which means the honest reply to that first Tarnock query — "have I wrecked it?" — usually no. Leave the motor off then ring Petrol in Diesel — that is how you keep it that way. Keep reading for three things: the effect petrol has inside a diesel engine, the clues of how far it has spread, and the way to make sure you don't repeat it.
What petrol in a diesel does to the engine
Passing through an engine, diesel is doing two jobs at once. It protects first, and only then does it burn. Extremely fine tolerances go into the fuel injectors and your high-pressure pump, and just your diesel flowing through keeps their surfaces from grinding together.
The second job petrol does not do at all, and the first it does badly. The knocking comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system rests on, and any pump working on that mixture is wearing itself.
Combined, those leave the shape of the problem plain. Contact doesn't do the damage — movement does. Petrol in the tank is a fuel problem. The beginning of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with your fuel to the injectors beyond it.
Four scenarios our technicians see around Tarnock: how bad is petrol in a diesel?
Filled up, never started. The best case there can be. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in the tank alone, it is drained and cleaned on the spot, and nothing more is needed.
A moment's running, or merely the ignition on. Your system has been primed, and so petrol has left your tank and got to the filter and the fuel lines. Normally nothing more than emptying, purging and sorting your filter, so still easy.
Those few miles driven meant your pump working on fuel thinned by petrol throughout. The work is your tank, the fuel lines, the fuel filter and fresh fuel through the entire system, and how hard the car was driven counts as much as how far. The school run to Weare Academy First School is one thing. Very different a second time: a trip to Wells, under 15 miles away, or any distance on the M5, under 3 miles from Tarnock, where your engine never stopped labouring hard.
Knocking, an uneven idle, smoke, a throttle gone soft: driven until it complained. The engine is telling you your fuel is no longer behaving like diesel. Stop wherever you are — the verge on Kingsway, a lay-by, a side street — and leave it where it is. Permanent damage is very rare when a vehicle is stopped early, and the drain and flush that still come first take care of it.
Stories Tarnock motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. A fuller tank of the same mixture is all you get, since topping up takes out nothing. The assumption behind the guidance — that diesel fuel systems accept petrol by percentage — is wrong.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through smaller components: that is how a newer diesel handles its fuel, and so the protection counts more, not less.
"It starts, it drives, so there is no harm" — the myth that catches more drivers than any other. Any petrol motor fed diesel generally won't run, and so the motorist stops and the damage stops with them. Feed petrol to a diesel and it normally starts, idles and pulls away as if nothing happened — all the while its pump is wearing. Being able to run isn't proof of being fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old fix for a distinct problem. The petrol is still inside your tank afterwards, and what it has weakened isn't put back.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol sits in the filter and lines, ready to go straight back through your pump at the next start. Also, a can of petrol drained by the roadside is genuinely dangerous.
How does petrol in a diesel happen?
A careless moment is rarely the cause, and nobody 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 won't fit a petrol car. That's how the forecourt makes it easy.
When habit and the vehicle stop matching, it takes place. A new motor, a hire car or a courtesy car. Two vehicles on one driveway, one petrol, one diesel. Your usual forecourt, its pumps now in a different order. A hurried fill on the way to Highbridge & Burnham with a train to catch. Years of petrol cars behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that is when. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Next time you fill up in Tarnock: preventing petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the pump's label; the colour is only a hint.
- Plenty of motors state the fuel inside the filler flap or on the cap, so check there on your first fill in any car you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, for a house with one of each.
- "Diesel", aloud, before you pick up the nozzle — every time a new or hired car gets its first tank. It seems silly. It works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck your phone away then keep your mind on the pump.
- Add-on devices exist for cars without one, and some diesels are built with a filler that won't take a petrol nozzle. Useful — but a backstop only, never a reason to stop checking the label.
- Spotting it halfway? Stop at once. A thinner mix results from less petrol in your tank, but your next stage stays the same: don't start the car.
Petrol already in a diesel in Tarnock? Begin here
The order of things is brief, then. Don't switch your ignition on, and don't fire it up. Ask the staff to help you push it clear of the pump if you're still on the forecourt, whether that's Shell or somewhere else. Next, 0333 366 0103. We'll ask what was put in, roughly how much, and if it has been run.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Tarnock page.
Why one petrol in a diesel task around Tarnock costs more than another
An honest single price doesn't exist here: four scenarios, four separate tasks. Which of them you are in is mostly what shifts the cost. The share counts next, meaning how much of the tank is petrol, followed by the position of your car and whether reaching it is safe for a technician.
That is why our engineers ask three queries before costing instead of after: what went in, how much, and whether it has run. The answers turn a range into a straight figure.
About Tarnock itself
Tarnock is a small hamlet in Somerset, situated inland near the villages of Biddisham and Badgworth. Tarnock lies close to the River Brue and is characterised by its low elevation of around 7 metres above sea level. Tarnock is predominantly composed of detached housing and is located near the city of Wells, which is approximately 11 miles away. Tarnock is also within commuting distance of larger cities, with London being around 120 miles to the east.
Across Somerset and around Tarnock: fuel drain cover
Biddisham, Rooks Bridge and Badgworth are among the places near Tarnock that the same teams work, answering petrol in diesel jobs across Tarnock's BS postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our engineers work, and your vehicle does not need to move to us.
In Tarnock and still at the petrol pump?
In that case, you couldn't be in a better place. Keep the car turned off, then ring.