Petrol in a Diesel Car in Dyffryn: How Worried Should You Be?
Less than you likely are, if it hasn't been started. Petrol resting in a diesel tank does nothing to the engine till something draws it through the system — your ignition priming your pump, the starter, or driving itself. So the fair answer to the first question everyone around Dyffryn asks, "have I wrecked it?", is normally no. Petrol in Diesel is who to call, with your engine kept off, 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 spread, and ways to make sure you don't do it again.
The engine and petrol in a diesel: what goes on
On its way through a motor, diesel does two jobs. It protects first, and after that does it burn. Designed to extremely fine gaps, the fuel injectors and your pump rely on your diesel flowing through them to keep their surfaces from wearing against one another.
Petrol does the first task poorly and the second not at all. The rattling comes from petrol being made not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the protection your system hinges on, and any pump working on that mixture is wearing itself.
Taken together, they show the shape the trouble takes. The damage is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, carried by your fuel, into your injectors downstream, which is why a pump that has worked on that petrol is where a mechanical fault begins.
Four scenarios we see around Dyffryn: how serious is petrol in a diesel?
Fuelled but not once started — the best it gets. Just the tank has petrol in it, so the job is emptying the tank and rinsing the system where the car sits. This situation can only truly happen at a forecourt: anywhere else, your car got there by being driven.
Your ignition turned on, or a short start. Petrol has left that tank and reached the filter and your lines, since the system has been primed. Still usually easy: drain, flush, and the filter dealt with.
Your pump has spent a couple of miles on weakened fuel — that's what driving it does. The work is that tank, the fuel lines, your filter and fresh fuel through the whole circuit, and how hard your car was driven matters as much as how far. On the school run to the local primary school, the miles is short. A run as far as Swansea, under 15 miles away, is a very different job. So is any distance on the M4, under 10 miles from Dyffryn, where the engine has been labouring hard the whole time.
Knocking, a ragged idle, smoke, a throttle gone soft: driven until it complained. The fuel isn't behaving like diesel any more, and your engine is telling you. Stop wherever you are — the verge on Humphreys Terrace, a lay-by, a side street — and leave it where it is. A car pulled over early very rarely has long-term damage, since the drain and the flush-through, which still come first, deal with it.
Stories Dyffryn 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. Nothing is removed when you top up — that tank simply holds more of the same mixture. Percentage is not how a diesel fuel system copes with petrol, however much that guidance supposes.
Not so: a current diesel copes with a bit of petrol. If anything, the reverse. At higher pressure, through more precise parts: that's how a current diesel handles its fuel, and so the protection counts more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches people. Any petrol engine fed diesel usually will not run, so the motorist stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. Fine and running aren't the same thing.
An old fix for a distinct fault lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol thinned is put back by it — and afterwards, the tank still contains that petrol.
If the motor has run, part of that petrol is in the filter and the fuel lines, not your tank — and your next start sends it right back through the pump. So the myth "drain the tank yourself and you are sorted" does not stand up. And, a can of petrol drained by the kerbside is truly dangerous.
Why petrol in a diesel occurs at all
Carelessness is rarely the cause, and nobody means to do it. The petrol nozzle is the slimmer of the two and slides into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol car at all. The forecourt makes it easy, and the mistake runs one way.
Habit and the car getting out of step is how it happens. Hire cars, courtesy cars, and cars that are new to you. One petrol and one diesel on the driveway of the same household. A forecourt you know, but with its pumps arranged differently. Filling up in a rush on the way to Maesteg, with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a motorist accustomed to petrol: precisely when it takes place. Add a back seat full of children, a phone call or rain, and the hand wins.
Next time you fill up in Dyffryn: preventing petrol in a diesel
- Green for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Go by the label on the pump, not the colour.
- Plenty of vehicles state the fuel inside your filler flap or on the cap, and so check there on your first fill in any motor you do not know.
- A coloured fob or a sticker on the diesel's key does more than any amount of intending to remember, for a house with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the petrol pump. It sounds daft and it does the trick.
- Put the phone away. This is an easy mistake to make while you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for vehicles without one. They are a backstop, not a reason to stop checking the pump.
- Less petrol means a thinner blend, so stop the moment you realise — though remembering that the next stage is unchanged. It is still not to start the car.
Already put petrol in a diesel in Dyffryn?
Short and simple, then, is the order of things. Starting it is out, and so is turning on the ignition. The staff on the forecourt — whether at Oils for Wales itself or wherever you filled up — will normally help push it clear of the petrol pump if you ask. Then phone 0333 366 0103 and tell us what went in, roughly how much, and whether it's run.
If it was AdBlue instead of petrol, say so. That is a separate fault — corrosion and deposits and not lost protection — and it has its own page for Dyffryn.
Why one petrol in a diesel job around Dyffryn costs more than another
Four separate tasks lie behind the four scenarios above — which is why there's no honest single quote. Which of them you're in is mostly what moves your cost. Where your car is counts too, and whether a technician can safely get to it, after the proportion of petrol to what your tank takes.
That is why we ask three queries before pricing rather than after: what was put in, how much, and if it's run. A range becomes a straight figure once the answers are in.
About Dyffryn itself
Dyffryn is a suburban area in Bridgend, situated near the riverside with an elevation of around 170 metres. Dyffryn lies close to several nearby communities, including Spelter, Caerau, and Nantyffyllon, and is approximately 12 miles from Swansea. Dyffryn has a population of around 2614 people, predominantly living in terraced housing. Dyffryn is also relatively distant from London, at a distance of around 152 miles.
Fuel drain cover around Dyffryn and across Bridgend
Petrol in diesel jobs around Dyffryn — part of the CF postcode area — go to vans that likewise cover the locations about it, Spelter, Caerau and Nantyffyllon among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our engineers work, and your car doesn't need to move to us.
Still at the pump around Dyffryn?
Then you are in the best position there is. Ring, and leave it switched off.