Petrol in a Diesel Car in Perran Downs: How Worried Should You Be?
Not started? Then less worried than you probably feel. Petrol resting in a diesel tank does nothing to the motor till something draws it through the system — the ignition priming your pump, the starter, or driving on its own. So the truthful answer to the first question anyone around Perran Downs asks, "have I ruined it?", is generally no. Keep it that way: leave the engine off and phone Petrol in Diesel. What petrol really does to a diesel, how to gauge how far it has travelled, and how to stop it from happening again: that's the remainder of this page.
Inside the engine: what petrol in a diesel really does
On its way through an engine, diesel does two tasks. It protects first, and only then does it burn. Extremely fine tolerances go into the fuel injectors and the high-pressure pump, and only your diesel flowing through keeps their surfaces from grinding together.
Of these two tasks, petrol handles the first poorly and the second never. A pump running on a petrol mix is wearing itself out, because petrol is thinner than diesel and strips out the lubrication your fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any clattering comes.
Combined, those make the shape of the problem clear. Contact does not do the damage — movement does. A tank with petrol in it is a fuel problem. Whatever a worn pump sheds travels on, borne by your fuel, into your injectors further along, which is why a pump that has worked on that petrol is where a mechanical problem starts.
Perran Downs, petrol in a diesel: four situations, from mild to significant
Filled up, not once started. The best case there is. Being at a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With the petrol held inside your tank alone, it's cleared and rinsed right where it stands, and nothing more is needed.
Started for a second, or just your ignition on. Once primed, the system has drawn petrol from your tank up to the filter and the lines. Drain, flush, deal with your filter: still usually straightforward.
Driven a couple of miles. Now your pump has spent these miles running on weakened fuel. Miles is only half of it; how hard it was driven counts equally. Either way the work includes the tank, your lines, your filter and fresh fuel through the entire system. The school run to St Hilary School is one matter. Any miles on the M5, over 50 miles from Perran Downs, means the motor has worked hard throughout, and a run to Truro, under 25 miles away, makes a very different task too.
Driven until it complained. Knocking, a ragged idle, smoke, a throttle that has gone soft. The fuel isn't acting like diesel any more, and your engine is saying so. Leave it wherever it has stopped: a lay-by, a side street, the verge on Grove Lane. Lasting damage is very unusual when a car is pulled over soon, and the drain and flush that still come first deal with it.
Petrol in a diesel myths Perran Downs people hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a fuller tank of the same mix. The idea behind the guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
"Modern diesels can handle a little petrol" — a myth, and nearer the opposite. Lubrication matters more on modern diesels, not less, since their fuel passes through smaller components at higher pressure.
This is the one that catches drivers. Myth: "If it starts and drives, there's no harm done." The driver of a petrol motor fed diesel usually stops, since it will not run, and the harm stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Being able to run is not the same as being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different fault. That petrol is still in the tank after that, and what it has weakened is not put back.
Once your engine has been run, part of the petrol sits in the filter and the fuel lines, not that tank — and the next start sends it right back through your pump. So the myth "drain your tank yourself and you're sorted" does not hold. Also, a can of petrol filled by the roadside is genuinely hazardous.
How does petrol in a diesel take place?
It's seldom carelessness, and nobody does it on purpose. A diesel nozzle mostly won't fit a petrol vehicle, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and only in that direction.
When routine and the vehicle stop matching, it occurs. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the drive of the same household. Your normal forecourt, its pumps now in a different order. Rushing for a train outside St Erth and filling up en route. The first fill-up in a diesel Volkswagen Tiguan after years of driving petrol is precisely the moment it occurs. With rain, a call arriving, or a car full of children to deal with, your hand just does what it always has.
Avoiding petrol in a diesel next time you fill up in Perran Downs
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Go by the label on the pump, not the colour.
- In a car you do not know, look inside the flap over your filler or at the cap before your first fill: plenty of motors print the fuel type there.
- Label the key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car gets its first tank. It sounds silly. It works.
- Put the 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 designed to reject a petrol nozzle, and add-on devices are available for the rest. Count it as a backstop, and keep reading the pump.
- Stop as soon as you realise. Less petrol inside the tank makes a thinner mixture. It does not change what to do next, which is still not to crank it.
Perran Downs: already put petrol in a diesel?
The order of things is short, then. Don't switch the ignition on, and do not start it. Ask the attendants to help you roll it clear of the petrol pump if you're still on the forecourt, whether that is JET or somewhere else. Then phone 0333 366 0103 and tell us what was put in, about how much, and whether it's run.
Say so if it was AdBlue instead of petrol: it's a different issue, with its own page for Perran Downs, since AdBlue brings corrosion and deposits instead of lost protection.
What makes one Perran Downs petrol in a diesel job cost more than the next
A fair single price doesn't exist here: four scenarios, four separate tasks. Chiefly, the cost moves with which one you're in. Next it's the share — how much petrol was put in against how much that tank holds — and then where the car is and whether a technician can get to it safely.
Before any quote, not after, we ask three questions: the fuel that went in, its amount, and if it has run. That's why. Given the replies, there is a straight figure rather than a range.
About Perran Downs itself
Perran Downs is a small village in Cornwall, situated on the coastal fringe of the South West region, with an elevation of around 77 metres. Perran Downs lies near the villages of Higher Downs and Rosudgeon, and is approximately 19 miles from the city of Truro. Perran Downs has a population of around 558 people, predominantly living in detached houses.
Fuel drain cover across Cornwall, Perran Downs included
Petrol in diesel call-outs around Perran Downs — part of the TR postcode area — go to teams that also cover the locations about it, Higher Downs, Rosudgeon and St Hilary among them. The car does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the pump in Perran Downs, still?
The best place there is, then — that's where you are. Call, and leave it switched off.