Should You Worry? Petrol in a Diesel Car in Rush Hill
Less than you probably are, if it hasn't been started. Until the ignition primes the pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which makes the truthful reply to that first Rush Hill question — "have I wrecked it?" — normally no. To keep the vehicle that way, ring Petrol in Diesel and leave your motor switched off. The rest of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its route through a motor. It lubricates first, and after that does it burn. What stops the surfaces inside your high-pressure pump and the injectors from wearing against each other is your diesel passing through them — they're made to extremely fine clearances.
Poorly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on that mixture to wear itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you get the knocking.
Put those together and the shape of the issue is plain. It is circulation that causes the harm, not contact. Where the petrol is only inside the tank, it is an issue of fuel, nothing more. Once the pump has been labouring on that petrol, a mechanical issue has started: anything shed by a pump that's wearing travels onward to your injectors with the fuel.
How bad is petrol in a diesel? Four scenarios our engineers see around Rush Hill
Filled up, never started. The best case there can be. At a forecourt, and truly only there, that petrol is still confined to your tank — since anywhere else the car was driven to get to it. The job is draining and flushing on the spot.
A brief spell of running, or merely your ignition on. With your system primed, the lines and filter already hold petrol that came from the tank. Drain, flush, deal with the fuel filter: still normally easy.
Those few miles driven meant the pump labouring on fuel thinned by petrol throughout. The work is that tank, your lines, the filter and fresh fuel through the entire circuit, and how hard the car was driven matters as much as how far. On the school run to St Philip's CofE Primary School, the miles is short. A run as far as Bath, under 3 miles away, is a very different job. So is any mileage on the M4, under 10 miles from Rush Hill, where your engine has been labouring hard throughout.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. The motor is telling you the fuel is no longer behaving like diesel. Stop where you are — on the verge on Clarks Way, at the kerb, down a side road — and do not move it. The drain and flush still go first, and they sort it out: when a vehicle is pulled over early, lasting damage is very uncommon.
What Rush Hill motorists get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Nothing comes out when you top up — that tank just carries more of the same mixture. A diesel fuel system doesn't tolerate petrol by percentage in the way that guidance supposes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Finer parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally leaves a motor that won't run: the driver stops, and so does the harm. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump grinds. Running is not the same as fine.
An outdated workaround for a distinct problem is behind this one. Myth: "Add some two-stroke oil and drive the car home." None of what petrol thinned is put back by it — and later, the tank still contains the petrol.
The next start draws petrol back round your pump from your lines and the filter, where some of that sits after your engine has been run. That's why draining the tank yourself doesn't sort it — a myth. And, a can of petrol drained by the roadside is genuinely dangerous.
How it happens: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the narrower of the two and slips 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.
It takes place when routine and your car stop matching. A new motor, a hire car or a courtesy car. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A rushed fill en route to Oldfield Park with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. Throw in a back seat full of children, a phone call or rain, and the hand wins.
How to prevent petrol in a diesel at your next fill-up in Rush Hill
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is just a hint.
- Plenty of motors state the fuel inside the filler flap or on the cap, so check it on your first fill in a car you do not know.
- Label the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- Before the nozzle leaves the pump the first time you fuel a hired or new motor, say "diesel" aloud. Silly, yes, yet it works.
- While you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the pump.
- Stop as soon as you realise. Less petrol inside that tank means a weaker mixture. It doesn't change what to do next, which is still not to start the vehicle.
Petrol already in a diesel in Rush Hill? Begin here
The order of things is brief, then. Leave it unstarted, with the ignition off as well. If you're still at the forecourt — Esso or anywhere else — ask the staff to help you roll the vehicle away from the petrol pump. Call 0333 366 0103 next, with three answers — your fuel, the rough amount, and if it's run.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Rush Hill, because AdBlue brings corrosion and deposits instead of lost lubrication.
Why one petrol in a diesel job around Rush Hill costs more than another
There's no fair single price for this, because the four scenarios above are four separate tasks. What shifts the cost is chiefly which of them you are in. Two things follow that: the petrol that went in as a proportion of what that tank holds, then the place your car is in and whether a technician can reach it safely.
That is why we ask three questions before quoting instead of after: what got in, how much, and whether it has run. Their answers are what change a range into one firm number.
About Rush Hill, briefly
Rush Hill is a suburban area located near the city of Bath in Somerset, sitting at an elevation of around 145 metres. Rush Hill is characterized by its predominantly semi-detached housing stock, with the neighbourhood forming part of the larger urban area surrounding Bath. Rush Hill is close to other nearby places such as Kingsway, Odd Down, and The Oval, and is situated inland, approximately 1.8 miles from Bath city centre.
Fuel drain cover in Rush Hill and across Somerset
Petrol in diesel jobs around Rush Hill — part of the BA postcode area — go to vans that also cover the locations round it, Kingsway, Odd Down and The Oval included. The vehicle does not need to come to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Rush Hill: still at the pump?
Then, you couldn't be in a better place. Switched off it remains; then phone.