Petrol in a Diesel Car in Tolvaddon: How Worried Should You Be?
Less than you likely are, provided it has not been started. Until the ignition primes the pump, the starter turns, or your car is driven, petrol in a diesel tank just sits there and does no harm. Which means the truthful reply to that first Tolvaddon question — "have I wrecked it?" — usually no. Petrol in Diesel is who to ring, with the engine left off, so it stays that way. What petrol really does to a diesel, how to judge how far it has 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 engine?
Two jobs fall to diesel on its route through a motor. Before it combusts, it protects — then it burns. What stops the surfaces inside the high-pressure pump and your injectors from wearing down against each other is your diesel passing through them — they're built to very fine gaps.
The second task petrol does not do at all, and the first it does badly. It is thinner than diesel and removes the lubrication the system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the trouble is clear when you put those together. Not contact but circulation is what causes the damage. Petrol in a tank is a fuel issue. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors further on.
How serious is petrol in a diesel? Four situations our engineers see around Tolvaddon
Fuelled, and never started: nothing beats it. That petrol is inside your tank and just your tank, and the task is a drain and a flush where the vehicle sits. This is the one scenario that can only truly occur on a forecourt, as anywhere else the vehicle has been driven to get there.
Started for a moment, or only the ignition on. Petrol has left the tank and reached the filter and your lines, since the system has been primed. Drain, flush, deal with the fuel filter: still normally straightforward.
Those few miles on the road meant the pump labouring on fuel weakened by petrol throughout. Distance is only half of it; how hard it was driven counts equally. Either way the work runs to your tank, your lines, the filter and clean fuel through the whole system. On the school run to Rosemellin Community Primary School, the miles is short. Any miles on the M5, over 50 miles from Tolvaddon, means the motor has worked hard throughout, and a run to Truro, under 15 miles away, makes a very different task as well.
Driven on till it complained — rattling, smoke, an uneven idle, a dead throttle. That's your motor telling you its fuel no longer is acting like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Tregarrian Road. The drain and flush-through still go first, and they sort it out: when a car is stopped soon, lasting damage is very uncommon.
Stories Tolvaddon drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. Topping up removes nothing; it gives you a bigger tank of the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance presumes.
Not so: a newer diesel copes with a bit of petrol. Rather, the opposite. A current diesel runs its fuel through more precise components at higher pressure, which makes the protection count more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it normally won't run, and so the motorist stops — and the harm stops with them. A diesel fed petrol usually starts, ticks over and drives away as though nothing has happened, while your pump wears. A running engine does not mean fine.
An outdated fix for a different issue is behind this one. Myth: "Add some two-stroke oil and drive it home." What petrol has weakened remains weakened, and the petrol remains inside the tank anyway.
Myth: "Drain that tank yourself and you're sorted." After the engine has run, some of the petrol is no longer inside your tank: it is in your filter and your lines, and it goes right back through the pump at the next start. It's also really dangerous to drain petrol into a can at the kerbside.
Why petrol in a diesel happens so easily
A careless moment is rarely the cause, and nobody means to do it. The forecourt makes it easy: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol vehicle at all. So the error runs one way.
It happens when habit and the car stop matching. Any car that is new to you — a hire car, on loan as a courtesy car, or brand new. Two vehicles on one drive, one petrol, one diesel. Your usual forecourt, its pumps now in a different order. Fuelling up in a rush on the way to Camborne, with a train to catch. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. With rain, a call arriving, or a car full of children to deal with, your hand just does what it has always done.
Next time you fill up around Tolvaddon: avoiding petrol in a diesel
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is only a hint.
- The first fill in a strange motor is the time to check the filler flap — on it, or on the cap, many vehicles state the fuel they take.
- Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key if a household has one of each. So mark it.
- Before the nozzle leaves the pump the first time you fuel a hired or new car, say "diesel" out loud. Silly, perhaps, yet it works.
- Mistakes like this are simple to make while your mind is on something else, so the phone goes away.
- Some diesels come with a filler built to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Less petrol makes a weaker mixture, so stop as soon as you notice — though remembering that your next step is unchanged. It's still not to crank it.
Petrol already in a diesel around Tolvaddon? Begin here
The order of things is short, then. Don't fire it up, and don't switch your ignition on. Still at the forecourt, at Morrisons or anywhere else? Ask the staff to help you push the car clear of the pump. What got in, about how much, and if it has run: tell us those when you ring 0333 366 0103.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a different fault — Tolvaddon has a page all for it.
What makes one Tolvaddon petrol in a diesel task cost more than the next
There is no honest single quote for this, since the four scenarios above are four separate jobs. Which of them you're in is mostly what moves your cost. After that it is the ratio — how much petrol was put in against how much the tank holds — and then where your car is and whether a technician can get to it safely.
That's why we ask three questions before costing instead of after: what was put in, how much, and if it's run. A range becomes a straight figure once those replies are in.
About Tolvaddon, briefly
Tolvaddon is a small village in Cornwall, situated near the coast and approximately 10.5 miles from Truro. Tolvaddon sits at an elevation of 83 metres, overlooking the surrounding countryside and nearby Tolvaddon Downs. Tolvaddon has a mix of housing types, with terraced houses being predominant, and is close to other local places such as Roskear Croft and South Tehidy.
Fuel drain cover across Cornwall, Tolvaddon included
Tolvaddon Downs, Roskear Croft and South Tehidy are among the locations near Tolvaddon that the same teams work, answering petrol in diesel calls across Tolvaddon's TR postcode area. Our technicians drain wherever your car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Tolvaddon: still at the petrol pump?
No position is better: that's where you are. Keep the vehicle switched off, and ring.