Pen-y-wern: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely are. Petrol sitting in a diesel tank does nothing to the motor till something pulls it through the fuel system — the ignition priming the pump, your starter, or the drive on its own. So the truthful answer to the first question anyone around Pen-y-wern asks, "have I wrecked it?", is generally no. To keep the vehicle that way, ring Petrol in Diesel then leave the engine switched off. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and ways to make sure you don't do it again.
Inside the motor: what petrol in a diesel does
Two jobs fall to diesel on its route round a motor. Oiling comes before burning; it does both. Designed to extremely fine gaps, your injectors and your pump depend on the diesel moving through them to stop their surfaces wearing against one another.
Of those two jobs, petrol manages the first badly and the second never. It's thinner than diesel and takes away the lubrication the fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the knocking comes from.
The shape of the issue is clear when you put those together. The damage is done by circulation, not by contact. Any tank with petrol in it is a fuel fault. 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 injectors beyond it.
Pen-y-wern, petrol in a diesel: four situations, from mild to significant
Filled up, never started. The best case there is. The petrol is inside that tank and only the tank, and the job is a drain and a flush where the vehicle stands. This is the one situation that can only really happen at a forecourt, since anywhere else the car has been driven to get there.
Ignition on, or started for a moment. The fuel system has been primed, and so petrol has left your tank and got to the filter and the lines. Still normally straightforward: drain, flush, and the filter seen to.
A couple of miles driven, and the pump has spent each of them running on thinned fuel. Mileage is only half of that; how hard it was driven matters equally. Either way this work runs to the tank, the lines, the filter and fresh fuel through the entire system. Short trips, like the school run to the local primary school, are one matter. Driving as far as Newport, under 25 miles away, makes a very different task — as does any mileage on the M4, under 25 miles from Pen-y-wern, with the motor running hard all the way.
Driven till it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Heads of the Valleys Road. The drain and flush still go first, and they deal with it: if a vehicle is pulled over quickly, lasting damage is very rare.
Stories Pen-y-wern motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Topping up takes out nothing; it gives you a bigger tank of the same mixture. That advice supposes a diesel fuel system tolerates petrol by percentage. It does not.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. A modern diesel sends its fuel through finer parts at higher pressure, which makes the lubrication matter more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel usually stops, because it will not run, and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually will; meanwhile the pump wears. Running does not mean fine.
Not so: a two-stroke additive makes it safe to drive home. It is an old fix, supposed for another fault. That petrol is still in the tank after that, and what it has weakened is not put back.
The next start sends petrol back round your pump from the lines and the fuel filter, where some of it sits once the engine has been run. That is why draining your tank yourself does not sort it — a myth. Also, a can of petrol filled at the kerbside is truly hazardous.
How does petrol in a diesel take place?
On purpose? Never. Through carelessness? Seldom, if ever. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly will not fit a petrol car. That's how the forecourt makes it straightforward.
Routine and the car getting out of step is how it takes place. A vehicle that's new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. Your ordinary forecourt, its pumps now in a different order. A rushed fill en route to Merthyr Tydfil with a train to catch. Exactly the moment it happens: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Throw in a back seat full of children, a phone call or rain, and habit wins.
Preventing petrol in a diesel next time you fill up around Pen-y-wern
- Read the petrol pump, not the colour. In the UK unleaded handles are generally green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in a strange vehicle is the time to check the filler flap — inside it, or on the cap, plenty of cars state which fuel they take.
- Label the key. In a household with one of each, a coloured fob or a sticker on your diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you pick up the nozzle — every time a new or hired car gets its first tank. It sounds silly. It does the trick.
- Mistakes like this are simple to make whilst your mind is on something else, and so the phone goes away.
- Some diesels come with a filler built to reject a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- Stop as soon as you notice. Less petrol inside your tank means a thinner mix. It doesn't change what to do next, which is still not to fire it up.
Already put petrol in a diesel in Pen-y-wern?
The order of things is short, then. Leave it unstarted, with your ignition off too. If you are still at the forecourt — Esso or anywhere else — ask the attendants to help you push the vehicle away from the petrol pump. Next, 0333 366 0103. We will ask what went in, about how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it is a separate problem, with its own page for Pen-y-wern, since AdBlue brings corrosion and deposits instead of lost lubrication.
Pen-y-wern petrol in a diesel jobs: why one costs more than another
An honest single price doesn't exist here: four situations, four separate jobs. Which of them you are in is mostly what shifts the cost. The share counts next, meaning how much of your tank is petrol, and then the position of your car and whether getting to it is safe for a van.
Three queries come first, before quoting, instead of after — what got in, how much, has it run — and that is the reason. Those replies change a range into a straight figure.
About Pen-y-wern, briefly
Pen-y-wern is a suburban area situated lakeside in Merthyr Tydfil, with a mix of terraced housing and a population of around 4517 residents. Pen-y-wern sits at an elevation of 328 metres, overlooking the surrounding landscape. Pen-y-wern is located near the communities of Pant, Dowlais, and Galon Uchaf, and is within commuting distance of Newport, which is approximately 19.8 miles away.
Pen-y-wern and Merthyr Tydfil: where our fuel drain cover runs
Pen-y-wern waits in the CF postcode area, and the vans that answer petrol in diesel jobs there work the places near it as well — Pant, Dowlais and Galon Uchaf among them. The car does not need to move to us: our engineers drain on a forecourt, in a supermarket car park, in a lay-by or on your own drive.
In Pen-y-wern and still at the petrol pump?
Then you are in the best spot there can be. Phone, and leave it turned off.