Kempes Corner: Petrol in a Diesel Car? How Worried to Be
Far less than you likely are, provided it has not been started. Everyone in Kempes Corner begins with "have I ruined it?", and the fair answer is generally no: petrol resting in that tank of any diesel stays harmless until priming, cranking or driving draws it into the system. Keep it that way: leave your engine off and phone Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it has gone, and how to keep it from happening again: that's the rest of this page.
Petrol in a diesel: what does it do to the motor?
On its way through a motor, diesel has two tasks. It lubricates to begin with, and only then does it burn. Designed to extremely fine tolerances, the injectors and the pump rely on your diesel moving through them to stop their surfaces wearing against one another.
Of these two tasks, petrol handles the first poorly and the second not at all. It is runnier than diesel and takes away the protection the system depends on, so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
Taken together, they make clear the shape the issue takes. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
How bad is petrol in a diesel? Four situations we see around Kempes Corner
Fuelled but not once started — as good as it gets. Being on a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol kept inside that tank alone, it's drained and rinsed on the spot, and nothing more is needed.
A brief spell of running, or just your ignition on. The system has been primed, so petrol has left the tank and got to your filter and the fuel lines. Drain, flush, see to your filter: still usually straightforward.
Some miles driven, and the pump has spent each of them working on thinned fuel. How hard the vehicle was driven counts as much as how far, and this work covers the tank, the lines, your filter and fresh fuel through the entire system. A school run to Lady Joanna Thornhill Endowed Primary School is one matter. A run as far as Canterbury, under 10 miles away, is a very different job. So is any mileage on the M20, under 3 miles from Kempes Corner, where your engine has been working hard throughout.
Driven on till it complained — rattling, smoke, a lumpy idle, a soft throttle. The engine is telling you the fuel is no longer acting like diesel. Stop wherever you are — the verge on Harville Road, a lay-by, a side street — then leave it where it is. Permanent damage is very unusual when a vehicle is pulled over quickly, and the drain and flush that still come first take care of it.
Stories Kempes Corner drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — the tank simply holds more of the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that advice presumes.
If anything, the reverse holds. Myth: "A modern diesel can cope with a bit of petrol." A modern diesel runs its fuel through finer components at higher pressure, which makes the protection count more, not less.
This is the one that catches drivers. Myth: "If it starts and drives, there's no harm done." A petrol engine fed diesel generally won't run, so the motorist stops and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated workaround for a different fault. What petrol has thinned remains diluted, and the petrol remains inside that tank regardless.
The next start sends petrol back round your pump from the lines and your filter, where some of that sits once your engine has run. That is why draining the tank yourself does not sort it — a myth. It is also genuinely risky to drain petrol into a can at the kerbside.
How does petrol in a diesel take place?
On purpose? Never. Through carelessness? Seldom, if ever. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol vehicle at all. The forecourt makes it simple, and the slip runs one way.
When habit and your car stop matching, it takes place. A motor that's new to you — a hire car, on loan as a courtesy car, or just bought. A household with one petrol and one diesel on the drive. The pumps in a different order on a familiar forecourt. A rushed fill on the way to Wye with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: precisely when it occurs. Throw in rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Kempes Corner motorists: how to avoid petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — yet not on each forecourt. Trust the label on the pump, not the colour.
- Check the filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on your first fill in any car you don't know.
- Mark 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 petrol pump the first time you fill a hired or new car, say "diesel" aloud. Daft, yes, but it works.
- Put your phone away. This is an easy mistake to make whilst you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to block a petrol nozzle, and aftermarket devices are available for the rest. Count it as a backstop, then keep reading the petrol pump.
- Stop as soon as you notice. Less petrol in your tank means a thinner blend. It doesn't change what to do next, which is still not to fire it up.
Kempes Corner: already put petrol in a diesel?
Then the order of things is brief. Starting it is out, and so is switching on the ignition. Yet at the forecourt, at Wye Motors or anywhere else? Ask the attendants to help you roll it clear of the petrol pump. What got in, about how much, and whether it has run: tell us that when you phone 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate problem — Kempes Corner has a page all for it.
Kempes Corner petrol in a diesel jobs: why one costs more than another
There's no fair single price for this, since the four scenarios above are four separate jobs. Mostly, your cost moves with which one you're in. Two things come after that: the petrol that went in as a share of what the tank holds, then the place the vehicle is in and whether our van can get to it safely.
Ahead of any quote, not after, come three queries: the fuel that went in, its amount, and whether it has run. That's why. With those answers, there is a straight figure instead of a range.
About Kempes Corner
Kempes Corner is a small hamlet in Kent, situated inland at an elevation of around 55 metres, approximately 9.9 miles from Canterbury. Kempes Corner is characterized by its predominantly detached housing stock, reflecting the area's rural nature. Kempes Corner sits within a network of nearby settlements, including Boughton Lees, Boughton Aluph, and Boughton Corner, in the wider countryside of Kent.
Kempes Corner and Kent: where our fuel drain cover runs
Boughton Lees, Boughton Aluph and Boughton Corner are among the places around Kempes Corner that the same teams work, answering petrol in diesel calls across Kempes Corner's TN postcode area. The vehicle doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump in Kempes Corner?
The best spot there is, then — that's where you are. Switched off it stays; then call.