Roose: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely are. Petrol sitting in a diesel tank does nothing to the engine until something draws it through your fuel system — your ignition priming the pump, your starter, or the drive on its own. So the fair answer to the first question everyone around Roose asks, "have I ruined it?", is generally no. Keep it like that: leave your engine off and phone Petrol in Diesel. Below, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to your engine?
Passing through an engine, diesel does two jobs at once. It combusts, and before it combusts it protects. What stops the surfaces inside the high-pressure pump and the injectors from wearing against one another is your diesel passing through them — they are made to very fine clearances.
Of these two tasks, petrol manages the first badly and the second never. Being less viscous than diesel, petrol strips away the protection a fuel system needs, so a pump on that mixture wearing itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the knocking.
Combined, those leave the shape of the issue clear. Contact doesn't do the damage — movement does. Any tank with petrol in it is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with your fuel to your injectors downstream.
Petrol in a diesel in Roose: how bad is it? Four cases
The best case there is: filled up, not once started. That petrol is in your tank and only the tank, and the job is a drain and a flush where your car stands. This is the one situation that can only really occur at a forecourt, since anywhere else your car has been driven to get there.
Your ignition turned on, or a brief start. Petrol has left that tank and reached the fuel filter and the lines, because the system has been primed. Drain, flush, see to the filter: still normally simple.
Some miles driven, and the pump has spent each of them running on diluted fuel. The work is the tank, the fuel lines, the fuel filter and fresh fuel through the entire system, and how hard your car was driven counts as much as how far. A school run to Roose School is one matter. A run as far as Lancaster, under 25 miles away, is a very different task. So is any distance on the M6, under 25 miles from Roose, where your engine has been working hard throughout.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. The fuel isn't behaving like diesel any more, and your motor is telling you. Leave it where it has stopped: a lay-by, a quiet street, the verge on Ashdown Road. Permanent damage is very rare if a car is pulled over soon, and the drain and flush-through that still go first sort it out.
Roose people and the petrol in a diesel myths they 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 bigger tank of the same mixture. The assumption behind the guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. More precise parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more drivers than any other. Diesel in a petrol motor normally leaves a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it generally fires up, ticks over and drives away as if nothing happened — all while its pump is wearing. Being able to run isn't proof of being fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct issue. None of what petrol thinned is put back by it — and later, that tank still contains the petrol.
If the engine has run, part of that petrol sits in your filter and the lines, not that tank — and the next start sends it right back through your pump. So the myth "drain that tank yourself and you're sorted" does not stand up. And, a can of petrol drained by the kerbside is genuinely dangerous.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol vehicle at all. So the slip runs one way.
The moment routine stops matching the car is the moment it happens. Any motor that's new to you — hired, on loan as a courtesy car, or just bought. One petrol and one diesel on the drive of the same household. A familiar forecourt with the pumps in a different order. A train to catch, and a hurried fill on the way to the nearest station. Exactly the moment it happens: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. With rain, a call coming in, or children to deal with, your hand simply does what it always has.
Next time you fill up around Roose: preventing petrol in a diesel
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on each forecourt. The label is what matters.
- Check the filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in a motor you don't know.
- One of each in the home? Mark your key to your diesel — a bright fob, a sticker — since intending to remember is not enough.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put 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 designed to refuse a petrol nozzle, and aftermarket devices exist for the remainder. Treat it as a backstop, and keep checking the pump.
- Less petrol means a thinner blend, and so stop as soon as you notice — though remembering that the next stage is unchanged. It's still not to crank it.
Put petrol in a diesel around Roose already?
The order of things is brief, then. Do not switch your ignition on, and do not start it. Still on the forecourt, at Shell or anywhere else? Ask the attendants to help you roll it clear of the petrol pump. What went in, about how much, and whether it's run: tell us that when you phone 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Roose page.
Roose petrol in a diesel jobs: why one costs more than another
There is no honest single price for this, since the four situations above are four separate jobs. Which of them you're in is mostly what moves the cost. Beyond that it's the share — how much petrol got in against how much your tank holds — and then where your car is and whether a van can reach it safely.
Three queries come first, before any quote, instead of after — what went in, how much, has it run — and this is the reason. A range becomes a straight figure when the replies are in.
About Roose itself
Roose is a suburban area in Cumbria, situated on the coastal fringe of the North West region. Roose lies near the coast at a relatively low elevation of 18 metres, and is located near other local places such as Yarlside and Roose Gate. Roose has a population of around 4204 people, predominantly living in semi-detached housing.
Fuel drain cover across Cumbria, Roose included
Yarlside, Abbotsmead and Roose Gate are among the locations around Roose that the same vans work, answering petrol in diesel jobs across Roose's LA postcode area. The car doesn't need to come to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the petrol pump around Roose, still?
The best spot there is, then — that's where you are. Keep the car turned off, and ring.