How Worried Should You Be? Petrol in a Diesel Car in Machen
Far less than you probably are, provided it hasn't been started. Till the ignition primes your pump, your starter cranks, or your vehicle is driven, petrol in a diesel tank just rests there and does no harm. Which means the truthful reply to that first Machen query — "have I ruined it?" — usually no. Petrol in Diesel is who to ring, with your motor kept off, and so it remains that way. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and ways to make sure you never do it again.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its route through a motor. It lubricates to begin with, and after that does it burn. What keeps the surfaces inside the high-pressure pump and the fuel injectors from wearing against one another is your diesel passing through them — they are built to extremely fine gaps.
Poorly at the first, not at all at the second: that's petrol. A pump running on a petrol blend is wearing itself out, since petrol is runnier than diesel and takes away the protection the fuel system relies 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 rattling comes.
The shape of the issue is clear once you put those together. Contact does not do the harm — movement does. Any tank with petrol in it is a fuel issue. Whatever a worn pump sheds travels on, carried by your fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical problem begins.
How bad is petrol in a diesel? Four situations our engineers see around Machen
Fuelled up, not once started. The best case there can be. That petrol is inside the tank and just your tank, and the task is a drain and a flush where your car stands. This is the one situation that can only really occur on a forecourt, since anywhere else your car has been driven to get there.
A moment's running, or merely the ignition on. Once primed, the fuel system has drawn petrol out of that tank as far as the filter and your lines. Normally little more than emptying, cleaning and sorting the filter, and so still straightforward.
Those few miles driven were the pump working on fuel thinned by petrol the whole way. Tank, lines, filter, then clean fuel run through the entire system: that is the work, and the way your car was driven matters as much as the mileage. Short trips, like the school run to the local primary school, are one thing. A run as far as Newport, under 10 miles away, is a very different job. So is any distance on the M4, under 5 miles from Machen, where the engine has been running hard throughout.
Rattling, a ragged idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is the motor signalling fuel that no longer runs like diesel. Whether it is the verge on Siloam Hill, a lay-by or a side road, stop there and leave it. Permanent damage is very unusual when a car is pulled over soon, and the fuel drain and flush-through that still go first sort it out.
Stories Machen drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mixture is all it gives, because topping up removes nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that advice assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through more precise components: that is how a newer diesel moves its fuel, so the protection counts more, not less.
Myth: "If it starts and drives, there's no damage done." This is the one that catches drivers. Feed diesel to a petrol engine and it normally will not run, so the motorist stops — and the harm stops with them. While your pump wears, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Running isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a separate fault. None of what petrol weakened gets put back by it — and afterwards, that tank still contains that petrol.
The next start draws petrol back round your pump from your lines and your filter, where some of it sits once the motor has run. That's why a DIY tank drain does not sort it — a myth. Draining petrol into a can at the kerbside is also really hazardous.
How does petrol in a diesel happen?
It's seldom carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol car at all. So the mistake runs one way.
The moment habit stops matching the vehicle is the moment it takes place. A new car, a hire car or a courtesy car. Two vehicles on one drive, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. Racing for a train outside Crosskeys and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it happens. Add rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Machen drivers: how to prevent petrol in a diesel next time
- The label is what counts, so read the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on every forecourt.
- Check your filler flap. Plenty of cars state the fuel inside the flap or on the cap. Look at it on the first fill in any motor you don't know.
- Mark the key. In a house with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember.
- It seems silly and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- 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 have a filler designed to refuse a petrol nozzle, and add-on devices exist for cars without one. They are a safety net, not a reason to stop reading the petrol pump.
- Noticing it halfway? Stop at once. A thinner mixture follows from less petrol inside the tank, yet the next step remains the same: do not start the vehicle.
Already put petrol in a diesel around Machen?
In that case, there's just a short order of things. Never start it, and do not turn the ignition on. If you are still at the forecourt — Esso or anywhere else — ask the staff to help you push the vehicle clear of the pump. Then call 0333 366 0103 and tell us what went in, roughly how much, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Machen has a page all for it.
Machen petrol in a diesel tasks: why one costs more than another
Four different tasks lie behind the four situations above — which is why there's no fair single price. The scenario itself does most of the work of moving your cost. Where the vehicle is matters too, and whether our van can safely get to it, after the share of petrol to what that tank holds.
That is why our engineers ask three queries before pricing rather than after: what got in, how much, and whether it's run. Those answers change a range into a straight figure.
About Machen, for a moment
Machen is a village situated on the banks of the Rhymney River in south Wales, with a mix of rural and suburban landscapes. Machen has a relatively low elevation of 59 metres above sea level and is located near the cities of Newport and Cardiff. Machen is characterized by its predominantly detached housing stock, reflecting its status as a desirable residential area. Machen is also close to several nearby places, including Nant-y-ceisiad, Craig-y-Rhacca, and Waterloo.
Across Caerphilly and in Machen: fuel drain cover
The vans answering petrol in diesel jobs in Machen, in the CF postcode area, also work the locations around it, Nant-y-ceisiad, Craig-y-Rhacca and Waterloo among them. The car doesn't need to come to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
In Machen and still at the petrol pump?
Then, you could not be in a better position. Keep it off. Phone.