How Worried Should You Be? Petrol in a Diesel Car in Chinatown
Provided it has not been started, you can worry less than you probably are. Everyone around Chinatown begins with "have I wrecked it?", and the honest answer is normally no: petrol left in that tank of a diesel stays harmless till priming, cranking or driving pulls it into the fuel system. Keep it that way: leave your engine off then ring Petrol in Diesel. Further down, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
What petrol in a diesel does to your engine
Two jobs fall to diesel on its route through a motor. It lubricates to begin with, and only then does it burn. Very fine clearances are built into your injectors and your high-pressure pump, and just your diesel running through stops those surfaces grinding together.
Of those two jobs, petrol handles the first poorly and the second not at all. It is thinner than diesel and strips away the lubrication your fuel system hinges on, and so a pump running on a petrol mix is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from.
Put those together and the shape of the trouble is plain. Not contact but circulation is what causes the harm. Petrol in a tank is a fuel problem. A pump that has been working on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the injectors further on.
How bad is petrol in a diesel? Four situations our engineers see in Chinatown
Filled up, never started. The best case there is. At a forecourt, and really only there, the petrol is still confined to the tank — because anywhere else your car was driven to get to it. The task is emptying and cleaning on the spot.
The ignition switched on, or a brief start. Petrol has come out of the tank and got to the fuel filter and the lines, since your system has been bled. Still usually straightforward: drain, flush, and your filter seen to.
A few miles driven, and the pump has spent each of them labouring on diluted fuel. Tank, lines, filter, then clean fuel run through the whole circuit: that is this work, and the way the car was driven matters as much as the distance. A school run to Soho Parish CofE Primary School is one matter. Any miles on the M1, under 10 miles from Chinatown, means the engine has worked hard throughout, and a run to Westminster, under a mile away, is a very different task too.
Driven on till it protested — clattering, smoke, a lumpy idle, a dead throttle. The fuel is not acting like diesel any more, and your engine is saying so. Stop wherever you are — the verge on Leicester Street, a lay-by, a side street — and leave the vehicle where it is. What comes first is still the fuel drain and flush, and that deals with it, with long-term damage very unusual when a car is stopped soon.
Chinatown drivers and that petrol in a diesel stories they hear
False: topping up to full with diesel makes it fine. It doesn't. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance supposes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. At higher pressure, through finer parts: that is how a newer diesel moves its fuel, and so the protection counts for more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches drivers. The driver of a petrol motor fed diesel normally stops, because it will not run, and the harm stops there. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile your pump grinds. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a separate issue. It doesn't put back what petrol has diluted, and the petrol is still in the tank later on.
Once the motor has been run, part of the petrol is in your filter and your lines, not your tank — and the next start pulls it right back through your pump. So the myth "drain that tank yourself and you are sorted" doesn't hold. It is also really hazardous to drain petrol into a can by the roadside.
Why petrol in a diesel happens at all
It is seldom carelessness, and nobody does it on purpose. One way only, since of the nozzles: the narrower petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly won't fit a petrol motor. That's how the forecourt makes it easy.
The moment routine stops matching the vehicle is the moment it happens. Any car that is new to you — a hire car, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. A familiar forecourt with the pumps in a different order. Racing for a train at Tottenham Court Road and filling up en route. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is exactly the moment it occurs. Your hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Chinatown people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — yet not on each forecourt. Trust the label on the petrol pump, not the colour.
- Inspect your filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on the first fill in a vehicle you don't know.
- Label the key. In a home with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- It sounds silly and it works: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, so put your phone away and keep your mind on the pump.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- As soon as you notice, stop: less petrol inside the tank means a weaker mix. What to do next does not change, though — still do not crank it.
Petrol already in a diesel in Chinatown? Begin here
Then the order of things is short. Leave it unstarted, with your ignition switched off too. Ask the staff to help you push it away from the petrol pump if you're still at the forecourt, whether that is Esso or anywhere else. What was put in, about how much, and whether it has run: tell us that when you call 0333 366 0103.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Chinatown, because AdBlue brings corrosion and deposits rather than lost lubrication.
One petrol in a diesel job in Chinatown costs more than another. Why?
There is no fair single price for this, since the four situations above are four separate jobs. What moves the cost is chiefly which of them you're in. The proportion counts next, meaning how much of your tank is petrol, followed by the location of the vehicle and whether getting to it is safe for our van.
That's why we ask three queries before quoting rather than after: what went in, how much, and if it's run. A range turns into a straight figure when the replies are in.
About Chinatown
Chinatown is a small suburban area in the heart of London, situated near the city's main entertainment and shopping districts. Chinatown sits at an elevation of 31 metres, close to the neighbouring areas of Soho, Strand, and Charing Cross. Chinatown is predominantly composed of flats, providing housing for its approximately 7258 residents. Chinatown is located very close to Westminster, at a distance of just 0.7 miles.
Chinatown and Greater London: where our fuel drain cover reaches
Soho, Strand and Charing Cross are among the places near Chinatown that the same teams work, answering petrol in diesel jobs across Chinatown's WC2H postcode area. You need not move your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places we drain.
In Chinatown and still at the petrol pump?
Then you're in the best place there is. Keep it off. Ring.