How Worried Should You Be? Petrol in a Diesel Car in Newchurch
If it has not been started, you can worry less than you likely are. Everyone in Newchurch starts with "have I wrecked it?", and the fair answer is generally no: petrol resting inside your tank of a diesel stays harmless until priming, cranking or driving pulls it into your fuel system. Leave your engine off then ring Petrol in Diesel — that keeps it like that. The rest of this page explains what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it does not happen to you a second time.
Your engine and petrol in a diesel: what goes on
On its way through a motor, diesel does two tasks. It burns, and before it ignites it lubricates. The high-pressure pump and your injectors are built to extremely fine gaps, and the diesel passing through them is what keeps those surfaces from grinding against each other.
Badly at the first, not at all at the second: that is petrol. Being less viscous than diesel, petrol strips out the protection a fuel system needs, so a pump on the mixture to wear itself. It is also made to resist igniting under compression — the opposite of what a diesel needs — which is where you get the clattering.
Put these together and the shape of the problem is clear. Contact doesn't do the damage — movement does. Petrol in the tank is a fuel issue. The start of a mechanical one is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the fuel injectors beyond it.
Four situations our technicians see around Newchurch: how bad is petrol in a diesel?
The best case there can be: filled up, not once started. On a forecourt, and genuinely only there, the petrol is still limited to that tank — because everywhere else the car was driven to get to it. The task is emptying and flushing on the spot.
Your ignition switched on, or a short start. Once primed, the fuel system has pulled petrol from the tank as far as your filter and the lines. Still usually easy: drain, flush, and the fuel filter seen to.
Those few miles on the road meant the pump running on fuel thinned by petrol the whole way. How hard your car was driven matters as much as how far, and the work covers the tank, the fuel lines, the fuel filter and clean fuel through the whole circuit. Short trips, such as the school run to the local primary school, are one thing. A run as far as Newport, under 25 miles away, is a very different job. So is any distance on the M4, under 25 miles from Newchurch, where the engine has been working hard the whole time.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone uneven. The fuel is not acting like diesel any more, and the engine is saying so. Pull up wherever you are — the verge on Kingsfield, a lay-by, a side street — then leave the vehicle there. A car stopped soon very rarely has permanent damage, as the drain and the flush-through, which still come first, sort it out.
Newchurch people and that petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mix. Percentage isn't how a diesel fuel system copes with petrol, however much that guidance presumes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. Protection counts more on newer diesels, not less, because their fuel passes through finer parts at higher pressure.
Myth: "If it starts and drives, there's no damage done." This is the one that fools people. The motorist of a petrol motor fed diesel usually has no choice but to stop, since it will not run, and the harm stops with them. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, while your pump wears. Being able to run is not proof of being fine.
An old fix for a different issue is behind this one. Myth: "Add some two-stroke oil and drive it home." That petrol is still inside that tank afterwards, and whatever it has diluted is not put back.
The next start draws petrol back round the pump out of the fuel lines and the filter, where some of that sits once your engine has run. That is why draining the tank yourself does not sort it — a myth. Also, a can of petrol drained at the roadside is truly dangerous.
Why petrol in a diesel takes place so easily
Carelessness is seldom the cause, and no one means to do it. A diesel nozzle mostly won't go into a petrol vehicle, but the narrower petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake straightforward, and just in one direction.
Routine and the car getting out of step is when it happens. Courtesy car, hire car, or a vehicle that's brand new. Two cars on one driveway, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. A hurried fill en route to Ebbw Vale Town with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: precisely when it happens. Add rain, a phone call or a back seat full of children, and the hand repeats what it has always done.
Newchurch drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is only a clue.
- Plenty of motors state the fuel inside your filler flap or on the cap, so check there on your first fill in a motor you don't know.
- Good intentions do less than a sticker or a fob in a bright colour on the diesel's key when a household has one of each. So label it.
- It sounds daft and it works: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Mistakes like this are straightforward to make while your mind is on something else, and so the phone goes away.
- Add-on devices are available for vehicles without one, and some diesels come with a filler that will not accept a petrol nozzle. Helpful — but a safety net at best, never a reason to stop checking the label.
- As soon as you realise, stop: less petrol in your tank means a thinner mixture. What to do next doesn't change, though — still do not fire it up.
Petrol already in a diesel in Newchurch? Begin here
The order of things is short, then. Don't turn your ignition on, and don't fire it up. Yet at the forecourt, at Tesco or anywhere else? Ask the attendants to help you push it clear of the pump. Then ring 0333 366 0103 and tell us what was put in, about how much, and whether it has run.
Corrosion and deposits are the issue with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and see its own Newchurch page.
Why one petrol in a diesel job around Newchurch costs more than another
A fair single price does not exist here: four scenarios, four separate jobs. Chiefly, the cost moves with which situation you are in. Two things follow that: the petrol that was put in as a proportion of what that tank holds, then the spot your car is in and whether a technician can reach it safely.
What was put in, how much, and whether it's run — three questions our engineers ask before quoting, not after, for precisely that reason. The answers change a range into a straight figure.
About Newchurch
Newchurch is a suburban area in Blaenau Gwent, situated on the riverside at an elevation of 297 metres. Newchurch has a mix of housing types, but is predominantly characterised by terraced homes. Newchurch is located near Ebbw Vale and Pont-y-Gof, and is within commuting distance of Newport, which is 16.4 miles away. Newchurch is part of a wider network of communities in south Wales, with nearby towns including Newtown.
Fuel drain cover around Newchurch and across Blaenau Gwent
Ebbw Vale, Pont-y-Gof and Newtown are among the places around Newchurch that the same vans work, answering petrol in diesel call-outs across Newchurch's NP postcode area. Our technicians drain wherever the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
At the petrol pump in Newchurch, right now?
Then, you could not be in a better position. Leave it switched off, and ring.