Longfield: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, worry far less than you likely are. Everyone around Longfield begins with "have I ruined it?", and the honest answer is usually no: petrol left in the tank of a diesel stays harmless until priming, cranking or driving draws it into the fuel system. Leave your engine off then ring Petrol in Diesel — that is how you keep it like that. The rest of this page covers what petrol really does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to the motor
Diesel has two tasks on its way through a motor. Before it burns, it protects — and then it combusts. The high-pressure pump and your injectors are designed to extremely fine clearances, and your diesel passing through them is what keeps those surfaces from wearing down against one another.
Of those two jobs, petrol manages the first poorly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the protection your system rests on, and any pump working on such a mixture is wearing itself.
Taken together, they show the shape the issue has. Contact does not do the damage — movement does. Where that petrol is only inside that tank, it is a problem of fuel, nothing more. After your pump has been labouring on that petrol, a mechanical fault has begun: anything shed by a pump that is wearing is carried onward to your injectors with the fuel.
Longfield, petrol in a diesel: four cases, from mild to serious
Fuelled up, never started. The best case there can be. At a forecourt, and genuinely only there, that 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.
A moment's running, or merely your ignition on. Petrol has come out of your tank and reached the fuel filter and your lines, because the fuel system has been bled. Drain, flush, deal with your filter: still normally easy.
Those few miles on the road meant the pump working on fuel diluted by petrol the whole way. The work is that tank, your lines, your filter and clean fuel through the whole system, and how hard your car was driven matters as much as how far. Short trips, such as the school run to Langafel Church of England Voluntary Controlled Primary School, are one thing. Any miles on the M20, under 3 miles from Longfield, means the engine has worked hard throughout, and a run to London, under 25 miles away, makes a very different job as well.
Knocking, an uneven idle, smoke, a throttle gone soft: driven until it complained. That's your engine telling you its fuel no longer is behaving like diesel. Pull up wherever you are — the verge on Station Road, a lay-by, a side street — and leave the car where it is. What comes first is still the drain and flush-through, and that deals with it, with permanent damage very unusual if a car is stopped quickly.
What Longfield people get told about petrol in a diesel — and the myths in it
False: topping up to full with diesel makes it fine. It doesn't. Topping up takes out nothing; it gives you a bigger tank of the same mixture. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance presumes.
"Newer diesels can handle a little petrol" — a myth, and nearer the opposite. Protection matters more on current diesels, not less, because their fuel passes through finer parts at higher pressure.
One myth that catches motorists out: if it starts and drives, it must be unharmed. The motorist of a petrol motor fed diesel usually stops, because it will not run, and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump wears. Fine and running are not the same thing.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, supposed for another issue. None of what petrol diluted gets put back by it — and afterwards, that tank still contains that petrol.
Myth: "Drain that tank yourself and you are sorted." Once your engine has been run, some of the petrol is no longer in the tank: it's in the filter and your lines, and it goes right back through your pump on the next start. Emptying petrol into a can by the kerbside is also really hazardous.
Petrol in a diesel: how does it take place?
Carelessness is seldom the cause, and nobody means to do it. One way only, because of the nozzles: the narrower petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
The moment routine stops matching the vehicle is the moment it takes place. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the driveway. The pumps in a different order on a well-known forecourt. Rushing for a train outside the nearest station and filling up en route. The first fill-up in a diesel Renault Clio after years of driving petrol is exactly the moment it occurs. Throw in a back seat full of children, a phone call or rain, and habit wins.
How to avoid petrol in a diesel at your next fill-up around Longfield
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is only a clue.
- In a vehicle you don't know, look inside the flap over your filler or at the cap before your first fill: many cars state the fuel there.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key if a home has one of each. So label it.
- It sounds daft and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Mistakes like this are easy to make whilst your mind is on something else, and so the phone goes away.
- Some diesels have a filler designed 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 checking the petrol pump.
- As soon as you notice, stop: less petrol inside the tank makes a thinner mixture. What to do next does not change, though — still do not start the car.
Petrol already in a diesel around Longfield? Begin here
The order of things is short, then. Don't turn the ignition on, and don't crank it. Still at the forecourt, at Shell or anywhere else? Ask the attendants to help you push the vehicle clear of the petrol pump. What went in, roughly how much, and if it has run: tell us those when you call 0333 366 0103.
Corrosion and deposits form the problem with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and read its own Longfield page.
Why one petrol in a diesel job in Longfield costs more than another
There is no fair single quote for this, since the four scenarios above are four separate jobs. The scenario itself does most of the work of moving your cost. Beyond that it is the share — how much petrol was put in against how much your tank holds — and then where your car is and whether a van can reach it safely.
That's why our engineers ask three queries before pricing rather than after: what was put in, how much, and whether it has run. A range becomes a straight figure when those replies are in.
About Longfield, briefly
Longfield is a village in Kent, situated inland at an elevation of 49 metres, and is located approximately 19.9 miles from London. Longfield has a mix of housing types, but semi-detached homes are predominant, and the village is near other communities such as Whitehill and Hartley. Longfield is part of the wider South East region, with nearby Westwood also being a neighbouring area. Longfield remains a relatively small village with a population of around 1619 residents.
Longfield and Kent: where our fuel drain cover reaches
Whitehill, Westwood and Hartley are among the locations around Longfield that the same vans work, answering petrol in diesel calls across Longfield's DA postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places our technicians work, and the car does not need to come to us.
Longfield: still at the petrol pump?
The best position there is, then — that is where you are. Keep it switched off, then ring.