Cottesmore: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you probably feel. Everyone around Cottesmore begins with "have I ruined it?", and the fair answer is usually no: petrol left inside the tank of any diesel stays harmless until priming, cranking or driving draws it into your fuel system. Leave your motor off and call Petrol in Diesel — that is how you keep it like that. What petrol really does to a diesel, how to judge how far it's gone, and how to keep it from happening again: that's the rest of this page.
The engine and petrol in a diesel: what happens
Diesel does two tasks on its way through a motor. It lubricates first, and after that does it burn. Very fine tolerances go into your injectors and your high-pressure pump, and just your diesel running through stops those surfaces grinding together.
Petrol does the first job poorly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump on the mixture wearing itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is why you get the knocking.
The shape of the issue is clear when you put those together. The harm is done by circulation, not by contact. Where that petrol is only in that tank, it is an issue of fuel, nothing more. Whatever a worn pump sheds goes on, borne by your fuel, into your injectors downstream, which is why a pump that has worked on the petrol is where a mechanical issue starts.
Four situations our technicians see in Cottesmore: how bad is petrol in a diesel?
Fuelled but never started — as good as it gets. The petrol is in the tank and just your tank, and the task is a drain and a flush where the car sits. This is the one scenario that can only truly occur on a forecourt, because anywhere else your car has been driven to get there.
Ignition on, or started for a moment. Once primed, the fuel system has pulled petrol from your tank as far as the fuel filter and the fuel lines. That is normally still a straightforward job — a drain, a flush, and the filter seen to.
Those few miles on the road meant the pump working on fuel thinned by petrol throughout. How hard your car was driven matters as much as how far, and the work covers that tank, the fuel lines, your filter and fresh fuel through the whole circuit. The school run to St Nicholas Church of England Primary School is one thing. Very different once more: a run to Peterborough, under 25 miles away, or any distance on the Great North Road, under 25 miles from Cottesmore, where your engine never stopped working hard.
Driven till it complained. Clattering, a ragged idle, smoke, a throttle that has gone soft. That is your motor telling you its fuel has stopped behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on St Nicholas Court. The drain and flush still come first, and they deal with it: if a car is stopped early, long-term damage is very uncommon.
Petrol in a diesel myths Cottesmore motorists hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed by topping up — you are left with a bigger tank, still the same mixture. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. A current diesel runs its fuel through smaller parts at higher pressure, which makes the lubrication count more, not less.
"It starts, it drives, so no harm done" — the myth that trips up most people than any other. Feed diesel to a petrol engine and it normally will not run, and so the motorist stops — and the damage stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, while your pump grinds. Being able to run isn't the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a different fault. What petrol has thinned remains thinned, and that petrol stays in that tank regardless.
The next start draws petrol back round the pump from your lines and your filter, where some of that sits once the engine has run. That's why draining your tank yourself does not leave you sorted — a myth. Draining petrol into a can at the roadside is also truly dangerous.
Petrol in a diesel: how does it happen?
No one does it on purpose, and it is rarely carelessness. A diesel nozzle mostly won't go into a petrol car, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error simple, and just in that direction.
When routine and the vehicle stop matching, it takes place. A new car, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. A forecourt you know, only with its pumps arranged differently. A train to catch, and a rushed fill on the way to Oakham. Years of petrol motors behind you, a diesel Renault Clio in front of you at the forecourt for its first tank — that's when. Add a back seat full of kids, a phone call or rain, and habit wins.
How to prevent petrol in a diesel on your next fill-up in Cottesmore
- Green for unleaded and black for diesel is normal in the UK — yet not on each forecourt. Trust the label on the pump, not the colour.
- Check the filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on the first fill in a motor you don't know.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key when a house has one of each. So label it.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems silly. It works.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the petrol pump.
- Some diesels have a filler built to block a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- As soon as you notice, stop: less petrol in your tank makes a thinner blend. What to do next doesn't change, though — still don't start the vehicle.
Cottesmore: already put petrol in a diesel?
The order of things is short, then. Leave it unstarted, with your ignition off as well. Ask the staff to help you push it away from the petrol pump if you're still on the forecourt, whether that's Pace or anywhere else. What got in, about how much, and if it has run: tell us that when you phone 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a different issue — corrosion and deposits and not lost protection — and it has its own page for Cottesmore.
Cottesmore petrol in a diesel jobs: why one costs more than another
There's no fair single quote for this, since the four situations above are four separate jobs. Chiefly, your cost moves with which situation you are in. The ratio matters next, meaning how much of that tank is petrol, followed by the location of the vehicle and whether reaching it is safe for a van.
That's why our technicians ask three queries before costing instead of after: what was put in, how much, and if it has run. Those replies are what change a range into one firm number.
About Cottesmore itself
Cottesmore is a small village in Rutland, situated in the East Midlands region of England, with a population of around 599 people. Cottesmore sits at an elevation of 135 metres, approximately 20 miles from Peterborough and 86 miles from London. Cottesmore is characterised by its predominantly detached housing stock, and is surrounded by nearby villages such as Barrow, Greetham, and Market Overton. Cottesmore remains a quiet, rural community with a strong sense of local identity.
Fuel drain cover across Rutland, Cottesmore included
Petrol in diesel calls around Cottesmore — part of the LE postcode area — go to teams that also cover the locations around it, Barrow, Greetham and Market Overton included. You need not move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
Still at the petrol pump around Cottesmore?
The best position there is, then — that's where you are. Keep the car switched off, then ring.