Wellsprings: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you probably feel. Until your ignition primes the pump, your starter cranks, or the car is driven, petrol in a diesel tank simply sits there and does no harm. Which makes the truthful reply to that first Wellsprings query — "have I wrecked it?" — usually no. Petrol in Diesel is who to ring, with your engine kept off, so it stays that way. Further down, you will find what petrol really does inside a diesel, how far it may have got, and how to stop it happening to you again.
Petrol in a diesel: what does it do to the engine?
Two tasks fall to diesel on its route through a motor. It ignites, and before it burns it protects. What keeps the surfaces inside your high-pressure pump and your injectors from grinding against each other is the diesel passing through them — they are made to extremely fine gaps.
Badly at the first, not at all at the second: that is petrol. A pump working on a petrol blend is wearing itself out, because petrol is thinner than diesel and takes away the protection the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that's where any clattering starts.
Seen together, they make clear the shape the trouble takes. Not contact but circulation is what causes the damage. Petrol in a tank is a fuel fault. Whatever a worn pump sheds travels on, carried by your fuel, into the fuel injectors downstream, which is why a pump that has worked on the petrol is where a mechanical fault begins.
Wellsprings, petrol in a diesel: four cases, from mild to serious
Filled but not once started — as good as it gets. Being at a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With the petrol held in that tank alone, it's cleared and flushed on the spot, and nothing more is needed.
Started for a moment, or just the ignition on. Your system has been bled, so petrol has left your tank and reached your filter and the lines. Drain, flush, deal with your filter: still usually easy.
Those few miles on the road meant your pump running on fuel thinned by petrol the whole way. Miles is only half of it; how hard it was driven counts just as much. Either way the work includes that tank, the lines, the fuel filter and clean fuel through the entire system. Driving the kids to Wellsprings Primary School is one sort of trip. A run as far as Wells, under 25 miles away, is a very different task. So is any distance on the M5, under 3 miles from Wellsprings, where the motor has been working hard the whole time.
Clattering, a lumpy idle, smoke, a throttle gone soft: driven until it complained. What you are hearing is the motor signalling fuel that no longer acts like diesel. Stop on the spot — on the verge on Triscombe Road, at the kerb, down a side road — and do not move it again. Lasting damage is very uncommon if a car is pulled over early, and the drain and flush-through that still come first deal with it.
What Wellsprings drivers get told about petrol in a diesel — and the stories in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. Nothing is removed by topping up — you are left with a fuller tank, still the same mixture. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
Not so: a modern diesel copes with a bit of petrol. If anything, the reverse. Lubrication counts more on modern diesels, not less, because their fuel passes through finer components at higher pressure.
One myth that catches drivers out: if it starts and drives, it must be unharmed. A petrol motor fed diesel normally won't run, so the motorist stops and the damage stops with them. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, whilst your pump grinds. Running does not mean fine.
Myth: "Add some two-stroke oil and drive it home." It's an outdated fix for a different problem. It does not put back what petrol has diluted, and that petrol is still in that tank afterwards.
Myth: "Drain the tank yourself and you're sorted." After your engine has been run, some of the petrol is no longer inside your tank: it is in the filter and your lines, and it goes straight back through the pump on the next start. Emptying petrol into a can by the roadside is also really hazardous.
Petrol in a diesel: how does it take place?
On purpose? Never. Through carelessness? Rarely, if ever. A diesel nozzle mostly won't fit a petrol motor, but the slimmer petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake simple, and only in one direction.
Habit and your car getting out of step is when it occurs. Any vehicle that is new to you — a hire car, on loan as a courtesy car, or just bought. Two cars on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Rushing for a train outside Taunton and fuelling up en route. Exactly the moment it occurs: after years of driving petrol, someone fills a diesel Renault Megane for the first time. Throw in a back seat full of kids, a phone call or rain, and the hand wins.
How to prevent petrol in a diesel at your next fill-up in Wellsprings
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is just a hint.
- Check your filler flap. Many vehicles state the fuel type inside the flap or on the cap. Look at it on the first fill in any car you do not know.
- Label the key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump. It sounds silly and it works.
- Thinking about something else is when this becomes an easy mistake to make, so tuck the phone away then keep your mind on the pump.
- Up to a point, a misfuel inhibitor helps: some diesels come with a filler designed to refuse a petrol nozzle, and add-on devices exist for the remainder. Treat it as a backstop, and keep checking the petrol pump.
- As soon as you realise, stop: less petrol inside the tank makes a weaker blend. What to do next does not change, though — still don't fire it up.
Put petrol in a diesel around Wellsprings already?
The order of things is short, then. Don't turn the ignition on, and do not start it. Ask the staff to help you push it away from the petrol pump if you're still at the forecourt, whether that is Texaco or anywhere else. What was put in, roughly how much, and if it's run: tell us that when you ring 0333 366 0103.
Say so if it was AdBlue rather than petrol: it is a separate fault, with its own page for Wellsprings, since AdBlue brings corrosion and deposits instead of lost protection.
What makes one Wellsprings petrol in a diesel job cost more than the next
The four scenarios above are four different tasks, so no single price for this would be fair. Chiefly, your cost moves with which situation you're in. The proportion matters next, meaning how much of the tank is petrol, followed by the location of the car and whether getting to it is safe for our van.
Before any quote, not after, come three questions: your fuel that went in, the volume, and if it has run. That's why. A range turns into a straight figure once those answers are in.
About Wellsprings and where it is
Wellsprings is a locality situated in a riverside setting in Somerset, with an elevation of 34 metres above sea level. Wellsprings lies near the cities of Wells and Taunton, and is surrounded by other localities such as Pyrland, Lyngford, and Rowbarton. Wellsprings has a population of approximately 3195 residents, who mostly reside in semi-detached housing. Wellsprings is located 132.9 miles west of London, in the South West region of England.
Wellsprings and Somerset: where our fuel drain cover reaches
Pyrland, Lyngford and Rowbarton are among the places near Wellsprings that the same teams work, answering petrol in diesel call-outs across Wellsprings's TA postcode area. Our technicians drain wherever the vehicle is — your own drive, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
At the petrol pump in Wellsprings, right now?
Then, you could not be in a better spot. Leave it switched off, then ring.