Should You Worry? Petrol in a Diesel Car in Pontlottyn
Provided it hasn't been started, you can worry less than you probably are. Petrol sitting in a diesel tank does nothing to the motor until something pulls it through the fuel system — the ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first query anyone in Pontlottyn asks, "have I ruined it?", is usually no. To keep the vehicle like that, ring Petrol in Diesel and leave your engine switched off. The remainder of this page explains what petrol really does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
Your engine and petrol in a diesel: what happens
Two tasks fall to diesel on its route round a motor. Before it combusts, it protects — and then it combusts. What stops the surfaces inside the high-pressure pump and the injectors from grinding against each other is the diesel flowing through them — they're built to extremely fine clearances.
Petrol handles 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 strips out the protection your fuel system depends on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the rattling comes.
Put these together and the shape of the trouble is plain. Contact does not do the damage — movement does. All a tank with petrol in it amounts to is a fuel problem. The start of a mechanical one is a pump that has been working on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors downstream.
Four situations our engineers see around Pontlottyn: how bad is petrol in a diesel?
Filled but never started — the best it gets. Just the tank has petrol in it, so the task is draining your tank and rinsing the system where the car sits. This scenario can only truly occur on a forecourt: anywhere else, the car got there by being driven.
A moment's running, or merely your ignition on. With the system primed, the lines and filter now contain petrol that came from that tank. Normally nothing more than emptying, purging and sorting your filter, so still simple.
Your pump has worked a couple of miles on weakened fuel — that is what driving the car does. Distance is only half of it; how hard it was driven counts just as much. Either way this work runs to that tank, the fuel lines, your filter and clean fuel through the whole system. Short trips, like the school run to the local primary school, are one matter. Very different once more: a run to Newport, under 25 miles away, or any distance on the M4, under 15 miles from Pontlottyn, where the engine kept working hard.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. The fuel is not acting like diesel any more, and the engine is saying so. Stop where you are — on the verge on Merchant Street, at the kerb, down a side road — and do not move it. Long-term damage is very rare when a car is pulled over quickly, and the fuel drain and flush-through that still go first sort it out.
Pontlottyn motorists and that petrol in a diesel stories they hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. A diesel fuel system does not accept petrol by percentage in the way that advice presumes.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the opposite. Lubrication matters more on newer diesels, not less, since their fuel passes through more precise components at higher pressure.
This is the one that fools motorists. Myth: "If it starts and drives, there's no harm done." Diesel in a petrol motor normally means a motor that will not run: the driver stops, and so does the damage. A diesel fed petrol normally starts, idles and drives away as though nothing has happened, while the pump grinds. A running engine doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct problem. What petrol has diluted remains thinned, and the petrol stays inside the tank regardless.
Once the motor has been run, part of the petrol sits in your filter and your lines, not that tank — and the next start sends it right back through the pump. So the myth "drain the tank yourself and you're sorted" doesn't hold. It is also really hazardous to drain petrol into a can at the kerbside.
Why petrol in a diesel happens at all
It's rarely carelessness, and no one does it on purpose. A diesel nozzle mostly won't go into a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake straightforward, and only in one direction.
When routine and the vehicle stop matching, it takes place. Any motor that is new to you — a hire car, on loan as a courtesy car, or just bought. Two vehicles on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. Racing for a train at the nearest station and fuelling up en route. Years of petrol motors behind you, a diesel Audi A4 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 the hand wins.
Pontlottyn people: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is usual in the UK — but not on each forecourt. Trust the label on the pump, not the colour.
- The first fill in a strange vehicle is the time to check the filler flap — on it, or on the cap, many cars state which fuel to use.
- Good intentions do less than a sticker or a fob in a vivid colour on your diesel's key if a house has one of each. So mark it.
- Before the nozzle leaves the pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Silly, yes, but it does the trick.
- Whilst you are thinking about something else, this is an easy mistake to make — so put your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to block a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop checking the pump.
- Less petrol makes a thinner blend, and so stop as soon as you realise — though remembering that the next step is unchanged. It's still not to start the car.
Petrol already in a diesel in Pontlottyn? Begin here
The order of things is brief, then. Leave it unstarted, with your ignition switched off too. Still at the forecourt, at Gulf or anywhere else? Ask the attendants to help you roll the car away from the petrol pump. Then phone 0333 366 0103 and tell us what went in, about how much, and if it's run.
Corrosion and deposits form the trouble with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and read its own Pontlottyn page.
Pontlottyn petrol in a diesel tasks: why one costs more than another
The four scenarios above are four separate jobs, so no single quote for this would be honest. Chiefly, the cost shifts with which situation you are in. Next it is the proportion — how much petrol went in against how much that tank holds — and then where your car is and whether our van can get to it safely.
What was put in, how much, and if it has run — three questions our engineers ask before costing, not after, for exactly that reason. Those replies turn a range into a straight figure.
About Pontlottyn and its setting
Pontlottyn is a village in Caerphilly, situated on the banks of the Rhymney River at an elevation of 249 metres. Pontlottyn has a mix of terraced housing and is located near the villages of Fochriw, Abertysswg, and Rhymney. Pontlottyn is approximately 16 miles from Newport and 136 miles from London, making it a rural community with some access to urban centres.
Fuel drain cover in Pontlottyn and across Caerphilly
The teams answering petrol in diesel jobs in Pontlottyn, in the CF postcode area, also work the locations around it, Fochriw, Abertysswg and Rhymney among them. The vehicle doesn't need to come to us: we drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
At the pump in Pontlottyn, still?
Then, you couldn't be in a better place. Turned off it stays; then ring.