Walton on the Hill: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as no one has started it. Everyone in Walton on the Hill begins with "have I ruined it?", and the honest answer is usually no: petrol resting in the tank of any diesel remains harmless until priming, cranking or driving pulls it into your fuel system. Keep it that way: leave the engine off and ring Petrol in Diesel. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and ways to make sure you never do it again.
What petrol in a diesel does to your engine
Diesel has two jobs on its way through a motor. It lubricates first, and only then does it burn. Your high-pressure pump and the injectors are designed to very fine gaps, and your diesel passing through them is what stops those surfaces from wearing down against one another.
Petrol does the first task poorly and the second not at all. A pump working on a petrol mix is wearing itself out, since petrol is runnier than diesel and strips out the lubrication the fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that is where any knocking comes.
The shape of the problem is clear when you put those together. Not contact but circulation is what causes the harm. All a tank with petrol in it amounts to is a fuel issue. A pump that has been working 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.
Four scenarios our technicians see around Walton on the Hill: how serious is petrol in a diesel?
Filled up, not once started. The best case there is. Being on a forecourt is what makes this possible: elsewhere, your car has been driven there to begin with. With the petrol held in that tank alone, it is emptied and cleaned right where it stands, and nothing more is needed.
Your ignition turned on, or a brief start. With your system primed, the lines and filter already hold petrol that came from your tank. Still usually simple: drain, flush, and the fuel filter dealt with.
The pump now worked a couple of miles on diluted fuel — that is what driving it meant. Tank, lines, filter, then fresh fuel run through the whole system: that is this work, and the way the vehicle was driven matters as much as the miles. Short trips, such as the school run to Arnot St Mary CofE Primary School, are one thing. Getting as far as Liverpool, under 3 miles away, makes a very different task — as does any miles on the M57, under 5 miles from Walton on the Hill, with the engine working hard the whole time.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. That is the engine telling you its fuel has stopped behaving like diesel. Stop wherever you are — the verge on Columbia Road, a lay-by, a side street — and leave the car there. A vehicle stopped soon very rarely has lasting damage, because the drain and the flush, which still come first, sort it out.
What Walton on the Hill people get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a bigger tank of the same mix. That guidance presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the reverse holds. Myth: "A newer diesel can cope with a bit of petrol." Smaller components and higher pressure are the way a modern diesel runs its fuel, and that makes the protection matter more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that catches motorists. The motorist of a petrol engine fed diesel usually stops, because it will not run, and the harm stops there. A diesel fed petrol usually starts, idles and drives away as if nothing has happened, while the pump grinds. Being able to run is not the same as being fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old fix for a distinct problem. The petrol is still inside that tank after that, and whatever it has diluted is not put back.
The next start sends petrol back round the pump from your lines and your filter, where some of that sits after the motor has run. That's why a DIY tank drain does not sort it — a myth. Besides, petrol cleared into a can by the road is truly risky.
Petrol in a diesel: how does it take place?
A careless moment is rarely the cause, and no one 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, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
It occurs when habit and the car stop matching. A new vehicle, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. A rushed fill en route to Walton (Merseyside) with a train to catch. A new-to-you diesel Volkswagen Tiguan, its first fuelling, and a motorist accustomed to petrol: precisely when it happens. Throw in rain, a phone call or a back seat full of kids, and your hand does what it has always done.
How to avoid petrol in a diesel at your next fill-up in Walton on the Hill
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Read the pump's label; the colour is only a clue.
- The first fill in a strange motor is the time to check the filler flap — inside it, or on the cap, plenty of vehicles state the fuel they take.
- One of each in the household? Label your key to the diesel — a bright fob, a sticker — because intending to remember is not enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the petrol pump. It sounds silly and it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop checking the pump.
- Less petrol makes a weaker mixture, so stop as soon as you realise — though remembering that the next stage is unchanged. It's still not to crank it.
Walton on the Hill: already put petrol in a diesel?
Short and simple, then, is the order of things. Don't switch the ignition on, and do not crank it. The attendants at the forecourt — whether at Sainsbury's itself or wherever you filled up — will normally help push it away from the petrol pump if you ask. Call 0333 366 0103 next, with three answers — the fuel, the approximate amount, and whether it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate problem — Walton on the Hill has a page all for it.
One petrol in a diesel job in Walton on the Hill costs more than another. Why?
There's no honest single price for this, because the four scenarios above are four different jobs. Chiefly, your cost shifts with which one you're in. After that it's the proportion — how much petrol was put in against how much that tank takes — and after that where the car is and whether a van can get to it safely.
What got in, how much, and if it has run — three questions we ask before quoting, not after, for exactly that reason. With the replies, you get a straight figure instead of a range.
About Walton on the Hill and where it is
Walton on the Hill is a suburban area in Merseyside, situated near the coast and approximately 2.6 miles from Liverpool. Walton on the Hill has a mix of terraced housing and is located at an elevation of 41 metres, with nearby areas including Walton, Anfield, and Kirkdale. Walton on the Hill is part of the larger Liverpool urban area, with the city centre being a short distance away.
Across Merseyside and in Walton on the Hill: fuel drain cover
Walton, Anfield and Kirkdale are among the spots around Walton on the Hill that the same teams work, answering petrol in diesel calls across Walton on the Hill's L postcode area. A forecourt, a supermarket car park, a lay-by or your own driveway are all spots our engineers drain, and the vehicle does not need to come to us.
Still at the petrol pump in Walton on the Hill?
Nothing beats it: that's where you now are. Keep it off. Call.