Limbury: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you likely feel. Till the ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which means the truthful reply to that first Limbury question — "have I wrecked it?" — usually no. Keep it that way: leave the engine off and call Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and the way to make sure you never do it again.
What petrol in a diesel does to your engine
Passing through a motor, diesel is doing two things at once. It lubricates to begin with, and only then does it burn. What keeps the surfaces inside the high-pressure pump and the fuel injectors from wearing against each other is the diesel passing through them — they're designed to extremely fine gaps.
The second job petrol does not do at all, and the first it does badly. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the protection your system rests on, and any pump working on such a mix is wearing itself.
The shape of the problem is clear when you put those together. Contact does not do the harm — movement does. All a tank with petrol in it amounts to is a fuel fault. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors downstream.
Four scenarios our engineers see in Limbury: how bad is petrol in a diesel?
Fuelled up, never started. The best case there can be. Only your tank has petrol in it, so the task is clearing the tank and rinsing the system where the vehicle sits. This situation can only truly happen at a forecourt: anywhere else, your car got there by being driven.
Started for a moment, or only your ignition on. Once primed, your system has drawn petrol out of that tank up to the filter and the fuel lines. Still normally straightforward: drain, flush, and the filter dealt with.
Your pump has worked a couple of miles on thinned fuel — that is what driving it does. Tank, lines, filter, then clean fuel run through the whole circuit: that's the work, and the way the vehicle was driven matters as much as the mileage. On the school run to The Meads Primary School, the distance is short. A run as far as St Albans, under 15 miles away, is a very different task. So is any miles on the M1, under 3 miles from Limbury, where the engine has been labouring hard the whole time.
Driven on until it protested — clattering, smoke, a ragged idle, a soft throttle. The motor is telling you your fuel is no longer behaving like diesel. Stop wherever you are — the verge on Icknield Way, a lay-by, a side street — and leave it there. A car stopped quickly very seldom has permanent damage, as the drain and the flush, which still come first, deal with it.
What Limbury drivers get told about petrol in a diesel — and the myths 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 mixture. A diesel fuel system does not accept petrol by percentage in the way that guidance presumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Lubrication matters more on newer diesels, not less, because their fuel passes through more precise components at higher pressure.
Myth: "If it starts and drives, there's no damage done." This is the one that catches motorists. Any petrol motor fed diesel generally will not run, so the driver stops and the damage 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 grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the car home." It's an outdated workaround for a separate issue. It doesn't put back what petrol has weakened, and that petrol is still in that tank later on.
Myth: "Drain the tank yourself and you're sorted." Once the engine has run, some of the petrol is no longer inside your tank: it is in the filter and your lines, and it goes right back through your pump on the next start. It is also truly hazardous to drain petrol into a can by the roadside.
How it happens: petrol in a diesel
A careless moment is rarely the cause, and no one means to do it. A diesel nozzle mostly will not fit a petrol car, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and just in that direction.
Habit and your car getting out of step is when it takes place. Hire cars, courtesy cars, and motors that are new to you. A household with one petrol and one diesel on the drive. A forecourt you know, only with its pumps arranged differently. Rushing for a train at Leagrave and fuelling up en route. A new-to-you diesel Volkswagen Passat, its first fuelling, and a motorist used to petrol: precisely when it takes place. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of kids.
Next time you fill up around Limbury: preventing petrol in a diesel
- The label is what counts, so read the pump rather than the colour: in the UK unleaded handles are usually green and diesel black, but not on each forecourt.
- Plenty of vehicles state the fuel inside the filler flap or on the cap, and so check there on your first fill in any motor you do not know.
- One of each in the house? Mark your key to the diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new motor, say "diesel" out loud. Silly, perhaps, but it works.
- While you are thinking about something else, this is an easy mistake to make — so put the phone away.
- Add-on devices are available for motors without one, and some diesels are built with a filler that won't take a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in the tank means a thinner mixture. What to do next does not change, though — still don't fire it up.
Limbury: already put petrol in a diesel?
The order of things is brief, then. Leave it unstarted, with the ignition off too. Yet at the forecourt, at Gulf or anywhere else? Ask the attendants to help you roll the vehicle clear of the pump. Phone 0333 366 0103 next, with three facts — your fuel, the approximate quantity, and whether it's run.
Say so if it was AdBlue rather than petrol: it is a separate problem, with its own page for Limbury, since AdBlue brings corrosion and deposits rather than lost lubrication.
Why one petrol in a diesel task in Limbury costs more than another
Four different tasks lie behind the four situations above — which is why there's no honest single quote. Mostly, the cost moves with which one you're in. Beyond that it's the ratio — how much petrol got in against how much the tank takes — and then where the vehicle is and whether a van can reach it safely.
Before any quote, not after, come three questions: your fuel that went in, the quantity, and if it's run. That's why. With the answers, there is a straight figure instead of a range.
About Limbury and where it is
Limbury is a suburban area in Bedfordshire, situated on the banks of the River Lea at an elevation of around 114 metres. Limbury lies approximately 30 miles north of London and 12 miles southeast of St Albans, with nearby neighbourhoods including Marsh Farm and Leagrave. Limbury has a population of around 8754 people, predominantly living in semi-detached housing. Limbury is characterized by its riverside setting and residential community.
Across Bedfordshire and around Limbury: fuel drain cover
Marsh Farm, Warden Hill and Leagrave are among the locations near Limbury that the same vans work, answering petrol in diesel calls across Limbury's LU postcode area. Our technicians drain wherever the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the pump around Limbury, still?
No position is better: that is where you are. Keep it off. Call.