Petrol in a Diesel Car in Pentre: How Worried Should You Be?
Provided it hasn't been started, worry far less than you probably are. Petrol resting in a diesel tank does nothing to the engine till something draws it through the system — the ignition priming your pump, the starter, or the drive itself. So the fair answer to the first query everyone in Pentre asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to ring, with your engine left off, and so it stays that way. Keep reading for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and the way to make sure you don't repeat it.
Inside the motor: what petrol in a diesel really does
Two tasks fall to diesel on its route through a motor. It burns, and before it ignites it protects. The high-pressure fuel pump and your injectors are made to very fine gaps, and your diesel passing through them is what stops those surfaces from wearing against one another.
The second task petrol doesn't do at all, and the first it does poorly. The clattering comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the lubrication the system depends on, and any pump running on such a mixture is wearing itself.
Seen together, they show what shape the trouble takes. It's movement that does the harm, not contact. Any tank with petrol in it is a fuel issue. After the pump has been running on that petrol, a mechanical problem has begun: whatever is shed by a pump that is wearing travels downstream to the injectors with your fuel.
Four scenarios our technicians see around Pentre: how bad is petrol in a diesel?
Filled up, and not started: no case is better. Just that tank has petrol in it, and so the job is draining your tank and purging the system where the vehicle stands. This scenario can only truly occur at a forecourt: anywhere else, the vehicle got there by being driven.
A brief spell of running, or just your ignition on. With the system primed, your lines and filter now contain petrol that came from that tank. Normally nothing more than clearing, rinsing and sorting the filter, and so still straightforward.
Driven a few miles. Now the pump has spent those miles working on weakened fuel. Mileage is only half of that; how hard it was driven counts just as much. Either way the work runs to your tank, your lines, your filter and fresh fuel through the whole system. On the school run to the local primary school, the miles is small. A run as far as Cardiff, under 25 miles away, is a very different task. So is any distance on the M4, under 10 miles from Pentre, where your engine has been running hard the whole time.
Driven till it protested. Clattering, a lumpy idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer acting like diesel. Leave it where it has stopped: a lay-by, a quiet street, the verge on Pleasant Street. The fuel drain and flush-through still go first, and they sort it out: when a car is pulled over soon, permanent damage is very rare.
What Pentre motorists get told about petrol in a diesel — and the myths in it
Myth: topping up to full with diesel makes it fine. It doesn't. Nothing is removed when you top up — your tank simply carries more of the same mixture. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance assumes.
If anything, the opposite holds. Myth: "A current diesel can cope with a bit of petrol." At higher pressure, through smaller components: that is how a newer diesel moves its fuel, so the protection matters for more, not less.
One myth that catches drivers out: 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 there. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, whilst your pump grinds. Running isn't the same as fine.
An outdated workaround for a separate problem lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." That petrol is still in your tank after that, and whatever it has diluted isn't put back.
Once your engine has been run, part of that petrol sits in your filter and your lines, not that tank — and your next start pulls it straight back through the pump. So the myth "drain the tank yourself and you are sorted" doesn't stand up. It is also genuinely risky to drain petrol into a can by the kerbside.
How does petrol in a diesel happen?
Nobody does it on purpose, and it's seldom carelessness. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one generally will not fit a petrol motor. That is how the forecourt makes it easy.
Routine and the car falling out of step is when it occurs. A motor that is new to you — a hire car, on loan as a courtesy car, or just bought. One petrol and one diesel on the drive of the same household. The pumps in a different order on a well-known forecourt. A train to catch, and a hurried fill en route to Ton Pentre. The first fill-up in a diesel Renault Megane after years of driving petrol is exactly the moment it takes place. With rain, a call arriving, or a car full of children to deal with, the hand just does what it has always done.
Pentre people: how to prevent petrol in a diesel next time
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what counts.
- Inspect the filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on the first fill in any vehicle you don't know.
- One of each in the house? Label the key to your diesel — a coloured fob, a sticker — since intending to remember is not enough.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Mistakes like this are straightforward to make whilst your mind is on something else, so your phone goes away.
- Add-on devices are available for motors without one, and some diesels are built with a filler that won't take a petrol nozzle. Useful — but a safety net at best, never a reason to stop checking the label.
- Spotting it halfway? Stop at once. A thinner mix results from less petrol in your tank, but your next step stays the same: don't start the vehicle.
Pentre: already put petrol in a diesel?
In that case, there's just a short order of things. Starting it is out, and so is turning on the ignition. If you are still at the forecourt — Texaco or anywhere else — ask the attendants to help you push it away from the pump. What got in, about how much, and whether it's run: tell us those when you call 0333 366 0103.
Say so if it was AdBlue rather than petrol: it's a different issue, with its own page for Pentre, because AdBlue brings corrosion and deposits rather than lost lubrication.
Pentre petrol in a diesel jobs: why one costs more than another
There is no fair single price for this, since the four scenarios above are four separate tasks. Mostly, your cost moves with which one you are in. After that it is the share — how much petrol got in against how much the tank takes — and then where the vehicle is and whether a technician can get to it safely.
Three queries come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Their answers are what change a range into one firm number.
About Pentre, briefly
Pentre is a suburban area in Rhondda Cynon Taf, situated on the riverside at an elevation of 161 metres. Pentre is located near the communities of Rhondda, Ton Pentre, and Gelli, and is approximately 18 miles from Cardiff. Pentre has a population of around 3708 people and is characterised by predominantly terraced housing. Pentre is also within commuting distance of major cities, with London being around 145 miles away.
Across Rhondda Cynon Taf and around Pentre: fuel drain cover
Petrol in diesel call-outs around Pentre — part of the CF postcode area — go to teams that also cover the locations round it, Rhondda, Ton Pentre and Gelli included. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our technicians drain, and your car doesn't need to come to us.
In Pentre and still at the petrol pump?
The best position there is, then — that is where you are. Phone, and leave it switched off.