Treneague: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, if it has not been started. Petrol sitting in a diesel tank does nothing to the motor till something draws it through the system — the ignition priming the pump, your starter, or the drive itself. So the truthful answer to the first question everyone around Treneague asks, "have I wrecked it?", is usually no. Keep it like that: leave your motor off and call Petrol in Diesel. What petrol actually does to a diesel, how to judge how far it's gone, and how to keep it from happening again: that is the rest of this page.
Petrol in a diesel: what does it do to the motor?
Two jobs fall to diesel on its route round a motor. It ignites, and before it ignites it lubricates. What stops the surfaces inside your high-pressure pump and the injectors from grinding against each other is your diesel passing through them — they're designed to extremely fine gaps.
Petrol does the first task poorly and the second not at all. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication your system rests on, and any pump working on such a blend is wearing itself.
The shape of the trouble is plain once you put those together. The damage is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel issue. After the pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that's grinding travels onward to your injectors with the fuel.
How serious is petrol in a diesel? Four situations we see around Treneague
Filled but not once started — the best it gets. On a forecourt, and really only there, the petrol is still confined to your tank — because everywhere else the car was driven to get to it. The task is emptying and flushing on the spot.
A moment's running, or merely the ignition on. Petrol has left your tank and reached your filter and your lines, since the system has been bled. That's normally still an easy job — a drain, a flush, and the fuel filter dealt with.
A few miles driven, and the pump has spent every one of them labouring on weakened fuel. The work is your tank, your lines, the filter and clean fuel through the entire system, and how hard the vehicle was driven counts as much as how far. On the school run to St Stephen Churchtown Academy, the distance is short. Any miles on the M5, over 50 miles from Treneague, means your engine working hard throughout, and a run to Truro, under 10 miles away, makes a very different task too.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. The fuel is not behaving like diesel any more, and the motor is telling you. Leave it wherever it stops: a lay-by, a side street, the verge on Kernick Close. A car stopped soon very rarely has long-term damage, as the drain and the flush, which still come first, sort it out.
Petrol in a diesel stories Treneague people hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, however much that guidance assumes.
Myth: a modern diesel copes with a bit of petrol. Rather, the opposite. Smaller components and higher pressure are how a current diesel runs its fuel, and that makes the lubrication count more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel normally stops, because it will not run, and the damage stops there. Feed petrol to a diesel and it usually fires up, ticks over and drives away like nothing happened — all while its pump is wearing. Running isn't the same as fine.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, meant for another problem. It does not put back what petrol has weakened, and the petrol is still in that tank after that.
The next start draws petrol back round your pump from the lines and the fuel filter, where some of it ends up once the motor has run. That's why draining the tank yourself does not sort it — a myth. On top of that, petrol drained into a can by the road is truly dangerous.
Why petrol in a diesel takes place at all
Carelessness is rarely the cause, and nobody means to do it. One way only, because of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol car. That is how the forecourt makes it easy.
It takes place when habit and the car stop matching. A vehicle that is new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the drive of the same household. A well-known forecourt with the pumps in a different order. Racing for a train at St Columb Road and filling up en route. Years of petrol cars behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that is when. With rain, a call arriving, or a car full of children to deal with, your hand just does what it always has.
Next time you fill up in Treneague: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on each forecourt. The label is what counts.
- Inspect your filler flap. Many cars state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you don't know.
- Mark your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It sounds silly and it does the trick.
- 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 built to reject a petrol nozzle, and add-on devices are available for the rest. Treat it as a safety net, then keep checking the petrol pump.
- Noticing it halfway? Stop there and then. A thinner mixture follows from less petrol in the tank, yet the next step remains the same: do not fire it up.
Put petrol in a diesel in Treneague already?
Short and simple, then, is the order of things. Don't crank it, and don't turn the ignition on. Still on the forecourt, at the nearest petrol station or anywhere else? Ask the attendants to help you push it clear of the petrol pump. Phone 0333 366 0103 next, with three facts — the fuel, the rough volume, and whether it's run.
If it was AdBlue and not petrol, say so. That is a separate fault — corrosion and deposits instead of lost lubrication — and it has its own page for Treneague.
What makes one Treneague petrol in a diesel task cost more than the next
There is no fair single quote for this, because the four scenarios above are four different jobs. Chiefly, your cost shifts with which one you're in. Two things come after that: the petrol that went in as a proportion of what that tank takes, then the spot the car is in and whether our van can reach it safely.
Ahead of any quote, not after, come three queries: your fuel that got in, the quantity, and whether it's run. That is why. Those answers are what change a range into one firm number.
About Treneague and its setting
Treneague is a small hamlet situated on the riverside in Cornwall, with Treneague being one of the many rural settlements in the area. Treneague sits at an elevation of around 85 metres, close to the nearby places of Trethosa, Terras, and Stepaside. Treneague is located near the city of Truro, which is approximately 9 miles away, and Treneague is characterized by its predominantly detached housing stock.
Across Cornwall and in Treneague: fuel drain cover
Our vans answering petrol in diesel calls in Treneague, in the PL postcode area, equally work the locations around it, Trethosa, Terras and Stepaside included. Our technicians drain wherever the car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump in Treneague, still?
No position is better: that is where you are. Ring, and keep it turned off.