Petrol in a Diesel Car in Builth Wells: How Worried Should You Be?
Provided it hasn't been started, you can worry less than you likely are. Until your ignition primes your pump, the starter cranks, or the car is driven, petrol in a diesel tank just rests there and does no harm. Which means the honest reply to that first Builth Wells question — "have I ruined it?" — usually no. Petrol in Diesel is who to call, with the engine kept off, so it remains that way. What petrol really does to a diesel, how to judge how far it's travelled, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to the motor?
Passing through a motor, diesel is doing two jobs at the same time. It combusts, and before it combusts it lubricates. What keeps the surfaces inside the high-pressure pump and the fuel injectors from wearing down against one another is the diesel flowing through them — they are designed to very fine clearances.
The second job petrol doesn't do at all, and the first it does badly. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, so a pump on the blend to wear itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
Put those together and the shape of the trouble is clear. Not contact but movement is what does the damage. All a tank with petrol in it amounts to is a fuel fault. After the pump has been running on that petrol, a mechanical fault has begun: whatever is shed by a pump that is wearing travels downstream to the fuel injectors with your fuel.
Four situations our technicians see around Builth Wells: how bad is petrol in a diesel?
Fuelled, and not started: no case is better. That petrol is inside the tank and just that tank, and the job is a drain and a flush where your car stands. This is the one scenario that can only truly happen at a forecourt, as anywhere else the vehicle has been driven to get there.
Your ignition switched on, or a brief start. The fuel system has been bled, so petrol has left the tank and reached the fuel filter and the lines. Still usually easy: drain, flush, and the filter seen to.
Your pump now spent a few miles on weakened fuel — that's what driving the vehicle meant. The work is that tank, the fuel lines, the filter and fresh fuel through the entire system, and how hard your car was driven matters as much as how far. On the school run to the local primary school, the distance is short. Any miles on the M50, under 50 miles from Builth Wells, means the engine working hard throughout, and a run to Hereford, under 50 miles away, makes a very different job as well.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The motor is telling you the fuel is no longer acting like diesel. Stop wherever you are — the verge on High Street, a lay-by, a side street — then leave it there. The fuel drain and flush-through still go first, and they sort it out: when a car is pulled over soon, lasting damage is very rare.
What Builth Wells people get told about petrol in a diesel — and the stories in it
False: topping up to full with diesel makes it fine. It does not. Nothing is removed when you top up — your tank simply carries more of the same blend. A diesel fuel system does not tolerate petrol by percentage in the way that guidance supposes.
Myth: a modern diesel copes with a bit of petrol. If anything, the opposite. A current diesel runs its fuel through finer parts at higher pressure, which makes the lubrication matter more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there is no harm done." A petrol motor fed diesel usually will not run, and so the motorist stops and the damage stops with them. Feed petrol to a diesel and it generally fires up, ticks over and drives away as if nothing happened — all the while its pump is wearing. Being able to run is not proof of being fine.
An outdated fix for a separate problem lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." It does not put back what petrol has diluted, and that petrol is still in your tank later.
Myth: "Drain your tank yourself and you are sorted." Once the engine has been run, some of that petrol is no longer in the tank: it's in the filter and your lines, and it goes straight back through the pump at your next start. Draining petrol into a can at the roadside is also really dangerous.
Why petrol in a diesel takes place so easily
On purpose? Never. Through carelessness? Rarely, if ever. One way only, since of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol car. That is how the forecourt makes it simple.
The moment routine stops matching the car is the moment it takes place. A vehicle that is new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a well-known forecourt. Racing for a train at Builth Road and filling up en route. A new-to-you diesel Renault Megane, its first fuelling, and a driver accustomed to petrol: precisely when it happens. Throw in a back seat full of kids, a phone call or rain, and the hand takes over.
Next time you fill up in Builth Wells: avoiding petrol in a diesel
- Check 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 matters.
- Many motors state the fuel type inside your filler flap or on the cap, and so check there on your first fill in a motor you don't know.
- One of each in the house? Mark your key to your diesel — a coloured fob, a sticker — because intending to remember isn't enough.
- Before the nozzle leaves the pump the first time you fuel a hired or new motor, say "diesel" aloud. Daft, yes, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler built to reject a petrol nozzle, and aftermarket devices are available for the remainder. Treat it as a safety net, then keep checking the pump.
- Noticing it halfway? Stop at once. A thinner mixture results from less petrol inside the tank, but your next step remains the same: do not crank it.
Put petrol in a diesel around Builth Wells already?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. Ask the staff to help you push it clear of the petrol pump if you are still on the forecourt, whether that's the nearest petrol station or anywhere else. Next, 0333 366 0103. We will ask what got in, roughly how much, and if it has been run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a different problem — Builth Wells has a page just for it.
One petrol in a diesel job around Builth Wells costs more than another. Why?
The four situations above are four separate jobs, so no single price for this would be honest. What moves the cost is chiefly which of them you are in. Two things come after that: the petrol that was put in as a share of what that tank holds, then the place the car is in and whether our van can get to it safely.
That is why our engineers ask three questions before quoting instead of after: what was put in, how much, and whether it has run. A range becomes a straight figure when the replies are in.
About Builth Wells itself
Builth Wells is a town situated on the River Wye in Powys, Wales, with a population of around 2752 people. Builth Wells has a mix of housing types, but semi-detached homes are predominant, and the town is surrounded by nearby places such as Llanelwedd and Llanddewir Cwm. Builth Wells sits at an elevation of 132 metres, close to the English border and within commuting distance of Hereford. Builth Wells is located approximately 146.7 miles from London, making it a relatively rural town in mid-Wales.
Across Powys and around Builth Wells: fuel drain cover
The teams answering petrol in diesel calls around Builth Wells, in the LD postcode area, also work the places around it, Llanelwedd, Llanddewir Cwm and Llanfaredd among them. A forecourt, a supermarket car park, a lay-by or your own driveway are all locations our technicians work, and the car does not need to move to us.
At the pump in Builth Wells, still?
Then, you could not be in a better place. Turned off it stays; then ring.