Tippity Green: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, provided it has not been started. "Have I wrecked it?" is the first thing anyone around Tippity Green asks, and the truthful answer is normally no, since petrol left in a diesel tank harms nothing till it's drawn through the system — by ignition priming, by your starter, or by being driven. Leave the engine off and call Petrol in Diesel — that keeps it that way. What petrol actually does to a diesel, how to judge how far it has gone, and how to keep it from happening again: that's the rest of this page.
Your engine and petrol in a diesel: what goes on
Diesel has two tasks on its way through a motor. It combusts, and before it combusts it lubricates. Extremely fine tolerances go into the injectors and the high-pressure pump, and just the diesel flowing through keeps their surfaces from grinding together.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, so a pump on that mixture to wear itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the rattling.
Together, those make the shape of the trouble clear. Contact doesn't do the damage — circulation does. Any tank with petrol in it is a fuel problem. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
Petrol in a diesel in Tippity Green: how bad is it? Four cases
The best case there is: filled up, not once started. Being at a forecourt is what makes this the case: elsewhere, your car has been driven there to begin with. With that petrol kept in your tank alone, it is emptied and rinsed on the spot, and nothing more is needed.
Started for a second, or only the ignition on. Once primed, your system has pulled petrol out of the tank as far as the filter and the lines. Normally nothing more than emptying, flushing and seeing to the fuel filter, so still simple.
A few miles driven, and the pump has spent each of them working on thinned fuel. The work is the tank, the lines, the filter and fresh fuel through the entire system, and how hard your car was driven counts as much as how far. On the school run to Springfield Primary School, the miles is short. Any mileage on the M5, under 3 miles from Tippity Green, means the engine has worked hard throughout, and a run to Birmingham, under 10 miles away, makes a very different task too.
Driven till it complained. Rattling, a lumpy idle, smoke, a throttle that has gone soft. That's the engine telling you its fuel no longer is acting like diesel. Pull up on the spot — on the verge on Dudley Road, at the kerb, down a side road — and don't move it. A vehicle stopped soon very seldom has long-term damage, as the fuel drain and the flush-through, which still come first, sort it out.
Tippity Green people and that petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — that tank just holds more of the same blend. The assumption behind that advice — that diesel fuel systems accept petrol by percentage — is wrong.
If anything, the reverse holds. Myth: "A current diesel can cope with a bit of petrol." Smaller components and higher pressure are how a modern diesel runs its fuel, and that makes the protection matter more, not less.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol engine and it normally won't run, so the motorist stops — and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. 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 separate problem. It does not put back what petrol has diluted, and the petrol is still inside your tank later on.
The next start draws petrol back round the pump from your lines and the filter, where some of it sits once your engine has run. That is why draining the tank yourself does not sort it — a myth. Clearing petrol into a can by the roadside is also really dangerous.
How petrol ends up: petrol in a diesel
No one does it on purpose, and it's seldom carelessness. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol motor at all. So the error runs one way.
When habit and the car stop matching, it happens. Courtesy car, hire car, or a motor that is brand new. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. Filling up in a hurry en route to Old Hill, with a train to catch. Years of petrol motors behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that's when. Throw in rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Avoiding petrol in a diesel next time you fill up in Tippity Green
- Check the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what matters.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel there.
- One of each in the household? Label the key to your diesel — a coloured fob, a sticker — because meaning to remember is not enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Daft, yes, yet it works.
- While you are thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to block a petrol nozzle, and aftermarket devices are available for the remainder. Treat it as a backstop, and keep reading the petrol pump.
- The moment you realise, stop: less petrol inside your tank makes a weaker mix. What to do next does not change, though — still do not start the vehicle.
Put petrol in a diesel in Tippity Green already?
Then the order of things is brief. Never start the car, and don't turn the ignition on. Still on the forecourt, at BP or anywhere else? Ask the staff to help you push the car clear of the petrol pump. What was put in, roughly how much, and if it has run: tell us those when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That is a different fault — corrosion and deposits instead of lost lubrication — and it has its own page for Tippity Green.
What makes one Tippity Green petrol in a diesel job cost more than the next
The four scenarios above are four separate jobs, so no single quote for this would be fair. Which of them you are in is chiefly what shifts your cost. Next it's the proportion — how much petrol got in against how much the tank takes — and then where your car is and whether our van can get to it safely.
Three queries come first, before quoting, instead of after — what was put in, how much, has it run — and this is the reason. Given the replies, you get a straight figure instead of a range.
About Tippity Green
Tippity Green is a suburban area in the West Midlands, situated near the River Rea and characterised by its semi-detached housing stock. Tippity Green sits at an elevation of 195 metres, overlooking the surrounding countryside and the nearby city of Birmingham. Tippity Green is located close to several other residential areas, including The Knowle, Brickhouse Farm, and Springfield, and is about 6.4 miles from Birmingham city centre.
Fuel drain cover across West Midlands, Tippity Green included
Tippity Green sits in the B postcode area, and our teams that answer petrol in diesel jobs there work the spots around it as well — The Knowle, Brickhouse Farm and Springfield among them. Our technicians drain where the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the pump in Tippity Green, right now?
No position is better: that's where you are. Leave the vehicle switched off, and ring.