How Worried Should You Be? Petrol in a Diesel Car in Rowledge
Unstarted? Then less worried than you likely are. Petrol resting in a diesel tank does nothing to your engine until something draws it through your fuel system — the ignition priming the pump, your starter, or the drive on its own. So the honest answer to the first question anyone in Rowledge asks, "have I ruined it?", is usually no. Keep it like that: leave the engine off then ring Petrol in Diesel. Below, this page sets out what petrol really does inside a diesel, how far it might have gone, and how to stop it happening to you again.
What petrol in a diesel does to your engine
Passing through a motor, diesel is doing two jobs at the same time. Oiling comes before burning; it does both. Built to very fine gaps, the injectors and the pump depend on your diesel flowing through them to stop their surfaces wearing against one another.
Petrol does the first job badly and the second not at all. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and takes away the protection your fuel system depends on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that's where any clattering comes.
Seen together, they show what shape the trouble has. Contact doesn't do the damage — movement does. Where that petrol is only inside your tank, it is a problem of fuel, nothing more. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with the fuel to the fuel injectors downstream.
How serious is petrol in a diesel? Four situations we see in Rowledge
Filled but never started — as good as it gets. At a forecourt, and truly only there, that petrol is still confined to your tank — because anywhere else the car was driven to reach it. The task is draining and purging on the spot.
A moment's running, or just the ignition on. Once primed, the system has pulled petrol from your tank up to your filter and the fuel lines. That's generally still a straightforward job — a drain, a flush, and your filter seen to.
Your pump now worked a few miles on weakened fuel — that is what driving the vehicle does. The work is that tank, your lines, the fuel filter and clean fuel through the whole system, and how hard the vehicle was driven counts as much as how far. Driving the children to Rowledge Church of England Controlled Primary School is one kind of trip. Driving as far as Winchester, under 25 miles away, makes a very different task — as does any distance on the M3, under 10 miles from Rowledge, with the motor working hard the whole time.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. That's your engine telling you its fuel no longer is behaving like diesel. Pull up where you are — on the verge on The Long Road, at the kerb, down a side road — and don't move it again. The fuel drain and flush still come first, and they sort it out: if a vehicle is stopped soon, permanent damage is very uncommon.
Myths Rowledge motorists hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Topping up takes out nothing; it gives you a fuller tank of the same mixture. That guidance assumes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. A current diesel sends its fuel through finer parts at higher pressure, which makes the protection matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there's no harm done." A petrol engine fed diesel normally won't run, so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally fires up, ticks over and drives away as if nothing has happened — all while its pump is wearing. Running isn't the same as fine.
Myth: "Add some two-stroke oil and drive the car home." It is an outdated workaround for a separate issue. None of what petrol diluted gets put back by it — and later, the tank still holds that petrol.
Myth: "Drain the tank yourself and you are sorted." Once the engine has run, some of that petrol is no longer inside your tank: it is in the filter and your lines, and it goes straight back through the pump at the next start. Draining petrol into a can by the kerbside is also really hazardous.
Petrol in a diesel: how does it happen?
Carelessness is seldom the cause, and nobody means to do it. A diesel nozzle generally will not fit a petrol motor, yet the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one error easy, and just in one direction.
The moment habit stops matching your car is the moment it occurs. A new motor, a hire car or a courtesy car. 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 fuelling up en route. Exactly the moment it occurs: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. Add a back seat full of children, a phone call or rain, and the hand wins.
Rowledge drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most generally do. Check the petrol pump's label; the colour is only a hint.
- In a vehicle you do not know, look inside the flap over the filler or at the cap before your first fill: plenty of vehicles state the fuel type there.
- Label your key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- It sounds silly and it does the trick: on the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Thinking about something else is when this becomes an easy mistake to make, and so put your 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 reject 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.
- As soon as you notice, stop: less petrol in that tank makes a weaker blend. What to do next does not change, though — still don't start the car.
Rowledge: already put petrol in a diesel?
The order of things is brief, then. Starting it is out, and so is switching on the ignition. Still on the forecourt, at Shell or anywhere else? Ask the attendants to help you push the car away from the pump. Then ring 0333 366 0103 and tell us what got in, roughly how much, and whether it's run.
Corrosion and deposits are the issue with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and read its own Rowledge page.
Rowledge petrol in a diesel tasks: why one costs more than another
Four separate jobs sit behind the four scenarios above — which is why there's no fair single price. The scenario itself does most of the work of moving your cost. Two things come after that: the petrol that went in as a proportion of what the tank holds, then the place the vehicle is in and whether a technician can get to it safely.
Three questions come first, before any quote, instead of after — what was put in, how much, has it run — and that is the reason. Those answers are what turn a range into one firm number.
About Rowledge, for a moment
Rowledge is a small village in Surrey, situated inland at an elevation of 111 metres, and is characterized by its predominantly detached housing stock. Rowledge lies near the villages of Holt Pound, Boundstone, and Shortheath, and is approximately 22.8 miles from the city of Winchester. Rowledge is also within commuting distance of London, being around 37.4 miles from the capital. Rowledge has a population of around 645 residents, making it a quiet and intimate community.
Across Surrey and around Rowledge: fuel drain cover
Holt Pound, Boundstone and Shortheath are among the places around Rowledge that the same vans work, answering petrol in diesel calls across Rowledge's GU postcode area. No need to move your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
At the pump in Rowledge, right now?
The best spot there is, then — that is where you are. Ring, and keep it switched off.