How Worried Should You Be? Petrol in a Diesel Car in Cornwell
Probably less than you are now — as long as nobody has started it. Everyone around Cornwell begins with "have I ruined it?", and the honest answer is generally no: petrol left inside your tank of any diesel remains harmless until priming, cranking or driving draws it into your fuel system. Keep it like that: leave your engine off then call Petrol in Diesel. Below, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
Your engine and petrol in a diesel: what goes on
On its way through a motor, diesel has two jobs. It protects to begin with, and after that does it burn. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing down against one another is your diesel passing through them — they are designed to extremely fine clearances.
Of those two jobs, petrol manages the first poorly and the second never. A pump running on a petrol blend is wearing itself out, since petrol is runnier than diesel and takes away 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's where the clattering comes.
Seen together, they show what shape the trouble has. The harm is done by circulation, not by contact. Any tank with petrol in it is a fuel problem. 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 your fuel to the injectors beyond it.
Four situations our engineers see in Cornwell: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there can be. Just your tank has petrol in it, and so the job is draining the tank and flushing the system where the car stands. This scenario can only really take place at a forecourt: anywhere else, the car got there by being driven.
Ignition on, or started for a moment. Once primed, the fuel system has pulled petrol out of your tank up to the filter and the fuel lines. Still normally simple: drain, flush, and the fuel filter sorted.
Those few miles on the road were the pump labouring on fuel diluted by petrol throughout. Tank, lines, filter, then fresh fuel put through the entire system: that is the work, and the way your car was driven matters as much as the mileage. On the school run to Kingham Primary School, the distance is small. A run as far as Oxford, under 25 miles away, is a very different job. So is any miles on the M40, under 15 miles from Cornwell, where the motor has been working hard the whole time.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and the motor is saying so. Stop on the spot — on the verge on A436, at the kerb, down a side road — and do not move it again. The drain and flush still go first, and they deal with it: when a car is pulled over soon, long-term damage is very unusual.
Cornwell people and that petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A fuller tank of the same mixture is all it gives, since topping up takes out nothing. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through more precise parts: that is how a current diesel handles its fuel, and so the lubrication counts more, not less.
The myth that catches drivers off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it normally will not run, so the motorist stops — and the damage stops with them. Feed petrol to a diesel and it usually starts, idles and drives away as if nothing happened — all the while its pump wears. Fine and running aren't the same at all.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, supposed for another issue. What petrol has weakened stays diluted, and that petrol remains inside the tank regardless.
The next start draws petrol back round the pump out of the fuel lines and the filter, where some of that ends up after the engine has been run. That is why draining your tank yourself doesn't leave you sorted — a myth. Also, a can of petrol drained by the kerbside is genuinely dangerous.
How does petrol in a diesel take place?
It is rarely carelessness, and nobody does it on purpose. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally will not fit a petrol vehicle. That's how the forecourt makes it straightforward.
The moment routine stops matching the vehicle is the moment it occurs. Courtesy car, hire car, or a motor that is brand new. A household with one petrol and one diesel on the driveway. A forecourt you know, only with its pumps arranged differently. Filling up in a rush en route to Kingham, with a train to catch. The first fill-up in a diesel Renault Clio after years of driving petrol is precisely the moment it happens. With rain, a call coming in, or a car full of children to deal with, your hand simply does what it has always done.
How to avoid petrol in a diesel at your next fill-up in Cornwell
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, yet not on every forecourt.
- Plenty of vehicles state the fuel inside the filler flap or on the cap, so check there on your first fill in a motor you don't know.
- One of each in the house? Mark your key to the diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- It seems silly and it works: on your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the petrol pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to reject a petrol nozzle, and aftermarket devices are available for the rest. Treat it as a backstop, and keep checking the pump.
- Less petrol makes a weaker blend, so stop the moment you notice — though remembering that the next stage is unchanged. It is still not to start it.
Cornwell: already put petrol in a diesel?
Then the order of things is short. Leave it unstarted, with your ignition off as well. Yet at the forecourt, at Esso or anywhere else? Ask the attendants to help you roll the vehicle away from the petrol pump. Phone 0333 366 0103 next, with three facts — your fuel, the rough quantity, and if it has run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different issue — Cornwell has a page all for it.
What makes one Cornwell petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four situations, four separate tasks. What moves your cost is mostly which of them you're in. Two things follow that: the petrol that got in as a share of what the tank holds, then the place your car is in and whether a technician can get to it safely.
What was put in, how much, and if it's run — three questions we ask before quoting, not after, for precisely that reason. With those replies, you get a straight figure instead of a range.
About Cornwell and its setting
Cornwell is a small hamlet in Oxfordshire, situated in the rolling countryside of the South East region. Cornwell sits at an elevation of 158 metres, surrounded by nearby places such as Salford and Adlestrop. Cornwell is characterized by its predominantly detached housing stock, reflecting its rural setting. Cornwell is located approximately 19.9 miles from Oxford and 70.1 miles from London.
Fuel drain cover in Cornwell and across Oxfordshire
The teams answering petrol in diesel calls in Cornwell, in the OX postcode area, equally work the places near it, Salford, Sarsden Halt and Adlestrop included. You need not move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all spots we drain.
Still at the petrol pump around Cornwell?
The best spot there is, then — that is where you are. Call, and leave it turned off.