Gwyddon: Petrol in a Diesel Car? How Worried to Be
Less than you probably are, if it hasn't been started. Until the ignition primes the pump, the starter cranks, or the car is driven, petrol in a diesel tank simply sits there and does no harm. Which means the honest reply to that first Gwyddon query — "have I wrecked it?" — usually no. Keep it like that: leave the motor off then call Petrol in Diesel. Read on for three things: the effect petrol has inside a diesel engine, the clues of how far it has spread, and the way to make sure you never do it again.
What petrol in a diesel does to the motor
On its way through a motor, diesel has two tasks. It protects first, and only then does it burn. Your high-pressure pump and the fuel injectors are designed to very fine gaps, and your diesel passing through them is what keeps those surfaces from wearing down against one another.
The second job petrol does not do at all, and the first it does poorly. The knocking 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 your system rests on, and any pump running on that mix is wearing itself.
Seen together, they make clear what shape the issue takes. The harm is done by movement, not by contact. Any tank with petrol in it is a fuel problem. 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 the fuel to the fuel injectors downstream.
Gwyddon, petrol in a diesel: four cases, from mild to serious
The best case there can be: filled up, not once started. Being at a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol kept in your tank alone, it's emptied and flushed right where it stands, and nothing more is needed.
The ignition turned on, or a brief start. Petrol has left your tank and reached your filter and the lines, because the system has been primed. Drain, flush, see to the fuel filter: still normally easy.
A couple of miles driven, and the pump has spent every one of them running on weakened fuel. The work is your tank, your lines, the filter and clean fuel through the whole system, and how hard the car was driven matters as much as how far. Short trips, such as the school run to the local primary school, are one matter. Any distance on the M4, under 10 miles from Gwyddon, means the engine working hard throughout, and a run to Newport, under 10 miles away, is a very different job as well.
Clattering, a ragged idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is your engine reporting fuel that no longer acts like diesel. Stop wherever you are — the verge on Upper Gwyddon Road, a lay-by, a side street — and leave the vehicle there. Lasting damage is very unusual if a vehicle is stopped soon, and the fuel drain and flush-through that still go first sort it out.
Petrol in a diesel myths Gwyddon people hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. A bigger tank of the same mix is all you get, because topping up removes nothing. A diesel fuel system doesn't accept petrol by percentage in the way that advice supposes.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. More precise parts and higher pressure are how a current diesel runs its fuel, and that makes the lubrication matter more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that fools people. Feed diesel to a petrol motor and it generally won't run, and so the driver stops — and the harm stops with them. Feed petrol to a diesel and it generally fires up, ticks over and drives away like nothing has happened — all the while its pump is wearing. Running does not mean fine.
Myth: a two-stroke additive lets you to drive home. It is an old workaround, meant for another problem. None of what petrol diluted is put back by it — and later, that tank still contains the petrol.
The next start draws petrol back round the pump out of your lines and the fuel filter, where some of it sits after the engine has run. That is why a DIY tank drain does not sort it — a myth. It is also really hazardous to drain petrol into a can by the kerbside.
How does petrol in a diesel take place?
On purpose? Never. Through carelessness? Rarely, if ever. The forecourt makes it simple: the petrol nozzle is the smaller of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
It takes place when habit and the car stop matching. Courtesy car, hire car, or a vehicle that is brand new. Households running one of each, petrol and diesel. A well-known forecourt with the pumps in a different order. A rushed fill on the way to Newbridge with a train to catch. Years of petrol cars behind you, a diesel Skoda Octavia in front of you on the forecourt for its first tank — that's when. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Gwyddon 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, even if most generally do. Check the pump's label; the colour is just a hint.
- In a motor you don't know, look inside the flap over your filler or at the cap before your first fill: many motors state the fuel there.
- 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.
- Before the nozzle comes off the petrol pump the first time you fill a hired or new vehicle, say "diesel" aloud. Daft, yes, but it does the trick.
- Mistakes like this are easy to make while your mind is on something else, so the phone goes away.
- Some diesels come with a filler designed to refuse a petrol nozzle, and devices you can add are available for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the pump.
- Stop the moment you notice. Less petrol in your tank makes a weaker blend. It does not change what to do next, which is still not to start the car.
Gwyddon: already put petrol in a diesel?
The order of things is brief, then. Leave it unstarted, with your ignition off as well. Ask the attendants to help you push it away from the pump if you're still on the forecourt, whether that's Texaco or anywhere else. What got in, about how much, and if it has run: tell us that when you ring 0333 366 0103.
Say so if it was AdBlue instead of petrol: it is a separate problem, with its own page for Gwyddon, since AdBlue brings corrosion and deposits rather than lost protection.
What makes one Gwyddon petrol in a diesel job cost more than the next
An honest single quote doesn't exist here: four situations, four separate jobs. Which of them you're in is chiefly what moves your cost. Two things come after that: the petrol that went in as a share of what your tank takes, then the spot the vehicle is in and whether our van can reach it safely.
What went in, how much, and if it has run — three questions our technicians ask before quoting, not after, for exactly that reason. The answers turn a range into a straight figure.
About Gwyddon, briefly
Gwyddon is a suburban area situated on the riverside in Caerphilly, with a mix of semi-detached housing and local amenities. Gwyddon sits at an elevation of 126 metres, overlooking the surrounding landscape. Gwyddon is located near the cities of Newport and Cardiff, and is close to nearby places such as Llanfach and Abercarn.
Fuel drain cover across Caerphilly, Gwyddon included
Llanfach, Abercarn and Persondy are among the places around Gwyddon that the same teams work, answering petrol in diesel call-outs across Gwyddon's NP postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all places we drain, and your car doesn't need to move to us.
Gwyddon: still at the petrol pump?
Then you're in the best place there is. Switched off it stays; then phone.