Petrol in a Diesel Car in Gunnersbury: How Worried Should You Be?
Not started? Then less worried than you probably feel. Until your ignition primes your pump, the starter cranks, or your vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which makes the honest reply to that first Gunnersbury question — "have I wrecked it?" — normally no. Keep it like that: leave your engine off then phone Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has spread, and the way to make sure you don't do it again.
Your engine and petrol in a diesel: what happens
Two tasks fall to diesel on its route through a motor. Lubricating comes before burning; it does both. What keeps the surfaces inside the high-pressure fuel pump and the fuel injectors from wearing against each other is the diesel passing through them — they are built to extremely fine clearances.
Petrol handles the first job badly and the second not at all. It's thinner than diesel and takes away the lubrication your fuel system depends on, and so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the clattering comes from.
Together, those make the shape of the trouble clear. It's circulation that causes the harm, not contact. Where the petrol is only inside your tank, it's a fault of fuel, nothing more. 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.
How bad is petrol in a diesel? Four scenarios our engineers see in Gunnersbury
Fuelled up, not once started. The best case there is. On a forecourt, and truly only there, that petrol is still limited to your tank — since anywhere else the car was driven to reach it. The task is emptying and rinsing on the spot.
Started for a moment, or only your ignition on. With the system primed, the lines and filter now hold petrol that came from the tank. Drain, flush, deal with the fuel filter: still usually easy.
Those few miles driven meant your pump running on fuel diluted by petrol the whole way. Mileage is only half of that; how hard it was driven counts just as much. Either way the work runs to the tank, the fuel lines, your filter and clean fuel through the whole circuit. Short trips, like the school run to Grove Park Primary School, are one thing. Very different once more: a trip to Westminster, under 10 miles away, or any miles on the M4, under a mile from Gunnersbury, where the motor kept running hard.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The fuel is not acting like diesel any more, and the engine is saying so. Pull up on the spot — on the verge on Cedars Road, at the kerb, down a side road — and don't move it. A car pulled over soon very seldom has permanent damage, as the drain and the flush, which still go first, sort it out.
Myths Gunnersbury drivers hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing comes out when you top up — that tank simply carries more of the same mixture. That advice presumes a diesel fuel system handles petrol by percentage. It does not.
"Newer diesels can handle a little petrol" — a myth, and closer to the reverse. More precise parts and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools people. A petrol engine fed diesel usually won't run, so the driver stops and the damage stops with them. While your pump grinds, a diesel fed petrol usually starts, ticks over and drives away as though nothing has happened. Running is not the same as fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, meant for another fault. It doesn't put back what petrol has diluted, and that petrol is still inside your tank after that.
Once the motor has been run, part of that petrol sits in the fuel filter and the fuel lines, not your tank — and your next start pulls it straight back through the pump. So the myth "drain the tank yourself and you are sorted" does not hold. Also, a can of petrol filled by the roadside is truly dangerous.
Why petrol in a diesel occurs at all
It is seldom carelessness, and nobody does it on purpose. A diesel nozzle generally will not fit a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and just in that direction.
Habit and the car getting out of step is when it occurs. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the driveway. A familiar forecourt with the pumps in a different order. Filling up in a hurry on the way to the nearest station, with a train to catch. Exactly the moment it takes place: after years of driving petrol, a driver fills a diesel Volkswagen Passat for the first time. Add a back seat full of children, a phone call or rain, and habit wins.
How to avoid petrol in a diesel on your next fill-up in Gunnersbury
- A green handle for unleaded and black for diesel is normal in the UK — but not on each forecourt. Trust the label on the pump, not the colour.
- Plenty of cars state the fuel inside the filler flap or on the cap, so check it on your first fill in any car you do not know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, for a house with one of each.
- "Diesel", out loud, before you lift the nozzle — every time a new or hired car needs its first tank. It sounds daft. It does the trick.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- Add-on devices are available for vehicles without one, and some diesels are built with a filler that won't accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Stop the moment you notice. Less petrol in the tank makes a thinner blend. It does not change what to do next, which is still not to crank it.
Already put petrol in a diesel in Gunnersbury?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. Still at the forecourt, at BP or anywhere else? Ask the staff to help you push the car clear of the pump. What got in, about how much, and whether it has run: tell us those when you ring 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Gunnersbury page.
One petrol in a diesel job around Gunnersbury costs more than another. Why?
The four scenarios above are four different jobs, so no single price for this would be honest. Mostly, your cost shifts with which one you're in. Two things come after that: the petrol that got in as a proportion of what that tank holds, then the spot your car is in and whether a van can reach it safely.
That's why our engineers ask three queries before costing rather than after: what went in, how much, and if it has run. A range turns into a straight figure when those replies are in.
About Gunnersbury and its setting
Gunnersbury is a suburban area in west London, situated approximately 6.1 miles from Westminster and close to the River Thames. Gunnersbury sits near the borders of Chiswick, Grove Park, and Acton Green, with a population of around 11902 people. Gunnersbury is characterized by its predominantly flat housing stock, which reflects the area's urban development. Gunnersbury remains a residential community within the wider London urban area.
Fuel drain cover across Greater London, Gunnersbury included
Chiswick, Grove Park and Acton Green are among the places near Gunnersbury that the same teams work, answering petrol in diesel calls across Gunnersbury's W postcode area. The car does not need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the petrol pump around Gunnersbury, right now?
The best place there is, then — that is where you are. Keep it off. Ring.