Petrol in a Diesel Car in Bentley: How Worried Should You Be?
Not started? Then less anxious than you probably feel. Until your ignition primes your pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank simply rests there and does nothing. Which makes the truthful reply to the first Bentley question — "have I wrecked it?" — normally no. Petrol in Diesel is who to ring, with your engine left off, so it remains that way. The remainder of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Petrol in a diesel: what does it do to the motor?
Diesel has two tasks on its way through a motor. It ignites, and before it combusts it protects. What stops the surfaces inside the high-pressure fuel pump and the injectors from wearing down against each other is your diesel passing through them — they're made to very fine tolerances.
Of these two jobs, petrol handles the first badly and the second never. It is thinner than diesel and removes the protection your fuel system rests on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
Taken together, they show the shape the issue has. Contact doesn't do the damage — circulation does. Petrol in the tank is a fuel problem. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to the injectors downstream.
Petrol in a diesel around Bentley: how bad is it? Four situations
Filled but never started — the best it gets. On a forecourt, and truly only there, that petrol is still limited to the tank — since anywhere else the car was driven to reach it. The job is draining and flushing on the spot.
Started for a moment, or only your ignition on. The system has been primed, so petrol has left your tank and got to the fuel filter and your lines. Normally nothing more than clearing, cleaning and seeing to the filter, and so still straightforward.
Driven a couple of miles. Now the pump has spent these miles labouring on diluted fuel. How hard the vehicle was driven matters as much as how far, and this work takes in that tank, the fuel lines, the filter and clean fuel through the whole circuit. The school run to Bentley Church of England Primary School is one thing. Any miles on the M3, under 10 miles from Bentley, means the engine has worked hard throughout, and a run to Winchester, under 25 miles away, makes a very different job as well.
It complained, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. What you are hearing is your engine reporting fuel that no longer runs like diesel. Pull up on the spot — on the verge on Main Road, at the kerb, down a side road — and don't move it again. What goes first is still the drain and flush, and that takes care of it, with permanent damage very unusual if a vehicle is pulled over early.
Bentley motorists and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Topping up removes nothing; it gives you a fuller tank of the same mix. The assumption behind that guidance — that diesel fuel systems accept petrol by percentage — is wrong.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Lubrication counts more on modern diesels, not less, because their fuel passes through finer parts at higher pressure.
"It starts, it drives, and so there is no harm" — the myth that trips up most drivers than any other. Diesel in a petrol motor generally means a motor that won't run: the driver stops, and so does the harm. Feed petrol to a diesel and it normally starts, ticks over and drives away as if nothing happened — all the while its pump is wearing. Being able to run is not the same as being fine.
Myth: "Add some two-stroke oil and drive it home." It's an old fix for a different problem. It doesn't put back what petrol has weakened, and the petrol is still inside that tank later on.
Myth: "Drain the tank yourself and you are sorted." Once the engine has run, some of the petrol is no longer in the tank: it is in the filter and your lines, and it goes right back through your pump on your next start. Also, a can of petrol filled at the roadside is genuinely hazardous.
Why petrol in a diesel occurs at all
On purpose? Never. Through carelessness? Seldom, if ever. One way only, because of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally won't fit a petrol motor. That's how the forecourt makes it simple.
When habit and the car stop matching, it takes place. Hire cars, courtesy cars, and cars that are new to you. Households running one of each, petrol and diesel. Your normal forecourt, its pumps now in a different order. Racing for a train outside Bentley (Hampshire) and filling up en route. Years of petrol cars behind you, a diesel Volkswagen Passat in front of you at the forecourt for its first tank — that's when. Throw in a back seat full of children, a phone call or rain, and habit takes over.
Next time you fill up around Bentley: preventing petrol in a diesel
- The label is what matters, so check the petrol pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- Many vehicles state the fuel inside your filler flap or on the cap, so check it on your first fill in any vehicle you don't know.
- Good intentions do less than a sticker or a fob in a bright colour on your diesel's key when a house has one of each. So label it.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It sounds daft and it works.
- Thinking about something else is when this becomes an easy mistake to make, so put the phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices are available for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Stop as soon as you realise. Less petrol in your tank means a thinner blend. It doesn't change what to do next, which is still not to start it.
Put petrol in a diesel around Bentley already?
Short and simple, then, is the order of things. Do not switch your ignition on, and don't fire it up. If you're still at the forecourt — Shell or anywhere else — ask the attendants to help you roll the car clear of the pump. Then ring 0333 366 0103 and tell us what went in, roughly how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate fault — Bentley has a page all for it.
Bentley petrol in a diesel jobs: why one costs more than another
The four scenarios above are four different jobs, so no single price for this would be fair. What moves your cost is chiefly which of them you're in. Where your car is counts too, and whether a van can safely get to it, after the share of petrol to what your tank takes.
Three queries come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. A range turns into a straight figure when those answers are in.
About Bentley and its setting
Bentley is a small village in Hampshire, situated inland at an elevation of 94 metres, with semi-detached housing being the predominant type. Bentley lies near the villages of Isington, Lower Froyle, and Blacknest, and is approximately 20.8 miles from Winchester. Bentley has a population of around 883 residents, and is located about 39.1 miles from London. Bentley remains a quiet, rural community with a strong sense of local identity.
Fuel drain cover in Bentley and across Hampshire
Isington, Lower Froyle and Blacknest are among the places near Bentley that the same vans work, answering petrol in diesel jobs across Bentley's GU postcode area. No need to bring the vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots we drain.
Still at the pump around Bentley?
The best place there is, then — that is where you are. Call, and keep it turned off.