Should You Worry? Petrol in a Diesel Car in Farnborough
Likely less than you are now — provided nobody has started the car. "Have I ruined it?" is the first question everyone around Farnborough asks, and the honest answer is usually no, because petrol left in a diesel tank harms nothing till it is dragged through the system — by ignition priming, by the starter, or by being driven. Leave the motor off then phone Petrol in Diesel — that keeps it that way. Further down, this page sets out what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
The motor and petrol in a diesel: what goes on
Diesel does two jobs on its way through an engine. Lubricating comes before burning; it does both. Built to very fine tolerances, the injectors and the pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Of these two tasks, petrol handles the first poorly and the second not at all. The rattling comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection the fuel system hinges on, and any pump working on that mix is wearing itself.
Put these together and the shape of the problem is clear. Contact doesn't do the harm — circulation does. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, carried by the fuel, into the fuel injectors further along, which is why a pump that has worked on that petrol is where a mechanical fault starts.
Petrol in a diesel in Farnborough: how serious is it? Four cases
The best case there can be: filled up, not once started. At a forecourt, and really only there, the petrol is still confined to that tank — because everywhere else the car was driven to get to it. The job is draining and flushing on the spot.
Your ignition switched on, or a brief start. Once primed, your system has drawn petrol from that tank up to the filter and the fuel lines. Still normally simple: drain, flush, and the filter sorted.
Driven a few miles. Now the pump has spent these miles running on diluted fuel. How hard the vehicle was driven matters as much as how far, and the work takes in that tank, your lines, your filter and clean fuel through the whole system. On the school run to Farnborough Primary School, the mileage is small. Driving as far as London, under 15 miles away, makes a very different task — as does any mileage on the M25, under 3 miles from Farnborough, with your engine labouring hard all the way.
Driven till it protested. Knocking, a lumpy idle, smoke, a throttle that has gone soft. That's your engine telling you its fuel no longer is acting like diesel. Leave it where it stops: a lay-by, a quiet street, the verge on Gladstone Road. What goes first is still the drain and flush-through, and that takes care of it, with lasting damage very unusual when a car is stopped quickly.
What Farnborough drivers get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up takes out nothing; it gives you a bigger tank of the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Protection counts more on current diesels, not less, because their fuel passes through smaller components at higher pressure.
Myth: "If it starts and drives, there's no harm done." This is the one that fools people. Diesel in a petrol motor usually leaves a motor that won't run: the driver stops, and so does the harm. While the pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running is not the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate issue. It doesn't put back what petrol has thinned, and the petrol is still in the tank later.
Once the motor has run, part of the petrol sits in the fuel filter and the fuel lines, not your tank — and your next start sends it straight back through your pump. So the myth "drain your tank yourself and you're sorted" doesn't stand up. On top of that, petrol emptied into a can by the road is truly hazardous.
Petrol in a diesel: how does it happen?
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle generally won't go into a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and only in that direction.
Habit and the vehicle getting out of step is how it occurs. Courtesy car, hire car, or a vehicle that's brand new. Two cars on one drive, one petrol, one diesel. A familiar forecourt with the pumps in a different order. Racing for a train at Orpington and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is exactly the moment it occurs. The hand does what it has always done once you add rain, a phone call or a back seat full of kids.
Farnborough drivers: how to prevent petrol in a diesel next time
- The label is what matters, and so check the petrol pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- In a motor you don't know, look inside the flap over the filler or at the cap before the first fill: many motors state the fuel type there.
- Label the key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It sounds daft. It works.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- Some diesels come with a filler designed to reject a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Stop as soon as you notice. Less petrol inside the tank makes a thinner mix. It doesn't change what to do next, which is still not to crank it.
Petrol already in a diesel around Farnborough? Begin here
Then the order of things is brief. Do not switch your ignition on, and don't fire it up. The staff at the forecourt — whether at Texaco itself or wherever you filled up — will usually help roll it away from the pump if you ask. Then call 0333 366 0103 and tell us what went in, about how much, and if it's run.
Say so if it was AdBlue instead of petrol: it's a separate problem, with its own page for Farnborough, since AdBlue brings corrosion and deposits instead of lost protection.
One petrol in a diesel job in Farnborough costs more than another. Why?
The four situations above are four different tasks, so no single price for this would be fair. The situation itself does most of the work of moving the cost. Two things come after that: the petrol that got in as a proportion of what the tank holds, then the spot your car is in and whether a van can get to it safely.
Before any quote, not after, come three queries: your fuel that was put in, its amount, and if it's run. That's why. With the replies, there is a straight figure rather than a range.
About Farnborough itself
Farnborough is a suburban area in Greater London, situated approximately 13 miles from central London and 106 metres above sea level. Farnborough is characterised by its semi-detached housing stock and is located near other suburban areas such as Locksbottom and Green Street Green. Farnborough has a population of around 4097 residents and is part of the wider London urban area.
Farnborough and Greater London: where our fuel drain cover runs
Petrol in diesel calls in Farnborough — part of the BR postcode area — go to vans that likewise cover the places round it, Locksbottom, Green Street Green and Crofton among them. No need to move the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
At the pump in Farnborough, right now?
Then you're in the best spot there can be. Ring, and keep it switched off.