Old Hill: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you probably are. "Have I wrecked it?" is the first thing everyone around Old Hill asks, and the truthful answer is generally no, because petrol resting in a diesel tank harms nothing until it's dragged through the fuel system — by ignition priming, by the starter, or by driving. Petrol in Diesel is who to phone, with your engine left off, so it stays that way. What petrol really does to a diesel, how to judge how far it's gone, and how to keep it from happening again: that's the rest of this page.
Inside the engine: what petrol in a diesel does
Passing through an engine, diesel does two things at the same time. It burns, and before it burns it protects. Extremely fine tolerances are built into the fuel injectors and the high-pressure pump, and only the diesel flowing through keeps those surfaces from grinding together.
The second task petrol doesn't do at all, and the first it does poorly. The rattling comes from petrol being designed 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 away the protection the fuel system rests on, and any pump working on such a mix is wearing itself.
Taken together, they show what shape the problem takes. Contact doesn't do the damage — movement does. Petrol in the tank is a fuel problem. After your pump has been working on that petrol, a mechanical issue has begun: anything shed by a pump that is grinding travels downstream to the injectors with the fuel.
How bad is petrol in a diesel? Four situations we see in Old Hill
Fuelled up, never started. The best case there is. Only your tank has petrol in it, so the task is emptying the tank and cleaning your system where your car sits. This situation can only truly happen on a forecourt: anywhere else, your car got there by being driven.
Your ignition turned on, or a brief start. Petrol has left that tank and reached the filter and your lines, because the fuel system has been bled. Still usually straightforward: drain, flush, and the filter seen to.
Those few miles on the road were your pump running on fuel thinned by petrol throughout. Tank, lines, filter, then fresh fuel put through the whole circuit: that is the work, and the way your car was driven matters as much as the mileage. The school run to Old Hill Primary School is one matter. Any mileage on the M5, under 3 miles from Old Hill, means the motor has worked hard throughout, and a run to Birmingham, under 10 miles away, is a very different task too.
Knocking, a lumpy idle, smoke, a throttle gone soft: driven until it complained. The engine is telling you the fuel is no longer behaving like diesel. Stop wherever you are — the verge on Mace Street, a lay-by, a side street — then leave it there. The drain and flush still come first, and they sort it out: if a vehicle is stopped soon, lasting damage is very uncommon.
What Old Hill 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 by topping up — you're left with a fuller tank, still the same mix. That advice supposes a diesel fuel system tolerates petrol by percentage. It doesn't.
Myth: a modern diesel copes with a bit of petrol. If anything, the opposite. Lubrication counts more on current diesels, not less, since their fuel passes through finer components at higher pressure.
"It starts, it drives, and so no harm done" — the myth that trips up more people than any other. The driver of a petrol motor fed diesel normally stops, since it will not run, and the harm stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually does; meanwhile the pump wears. Running isn't the same as fine.
Not so: a two-stroke additive lets you to drive home. It was an old workaround, supposed for another problem. None of what petrol thinned gets put back by it — and later, that tank still holds the petrol.
Myth: "Drain your tank yourself and you're sorted." Once the engine has been run, some of that petrol is no longer in your tank: it's in your filter and your lines, and it goes right back through the pump on your next start. Draining petrol into a can by the roadside is also really hazardous.
How does petrol in a diesel take place?
Nobody does it on purpose, and it is rarely carelessness. A diesel nozzle mostly won't fit a petrol vehicle, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake simple, and just in one direction.
Routine and the vehicle getting out of step is how it happens. A car that's new to you — a hire car, on loan as a courtesy car, or brand new. Two cars on one driveway, one petrol, one diesel. A forecourt you know, only with its pumps arranged differently. Racing for a train outside the nearest station and filling up en route. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it occurs. Add rain, a phone call or a back seat full of kids, and your hand does what it has always done.
How to prevent petrol in a diesel on your next fill-up in Old Hill
- Check the pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on each forecourt. The label is what matters.
- Inspect your filler flap. Plenty of vehicles state the fuel inside the flap or on the cap. Look at it on the first fill in any vehicle you do not know.
- Good intentions count for less than a sticker or a fob in a vivid colour on your diesel's key if a household has one of each. So mark it.
- 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 pump. It sounds daft and it does the trick.
- Mistakes like this are simple to make whilst your mind is on something else, and so the phone goes away.
- Some diesels come with a filler built 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 reading the petrol pump.
- Noticing it halfway? Stop at once. A thinner blend results from less petrol inside the tank, but your next step stays the same: do not start the car.
Put petrol in a diesel in Old Hill already?
The order of things is brief, then. Do not start the vehicle, and don't switch your ignition on. The staff at the forecourt — whether at Esso itself or wherever you filled up — will normally help push it away from the pump if you ask. Call 0333 366 0103 next, with three facts — your fuel, the rough quantity, and whether it has run.
If it was AdBlue and not petrol, say so. That is a different problem — corrosion and deposits rather than lost lubrication — and it has its own page for Old Hill.
Old Hill petrol in a diesel tasks: why one costs more than another
There's no honest single quote for this, because the four scenarios above are four different jobs. The situation itself does most of the work of moving your cost. Two things follow that: the petrol that was put in as a proportion of what that tank takes, then the place the car is in and whether a van can get to it safely.
That's why we ask three queries before costing instead of after: what got in, how much, and whether it has run. Given those answers, you get a straight figure instead of a range.
About Old Hill, for a moment
Old Hill is a village situated on the riverside in the West Midlands, with an elevation of around 115 metres. Old Hill lies approximately 6.9 miles west of Birmingham and is surrounded by nearby places such as Bowling Green, Cradley Heath, and Darby End. Old Hill has a population of around 5886 people and is predominantly composed of terraced housing. Old Hill is located about 106.2 miles northwest of London.
Across West Midlands and in Old Hill: fuel drain cover
Petrol in diesel calls around Old Hill — part of the B postcode area — go to vans that likewise cover the spots around it, Bowling Green, Cradley Heath and Darby End included. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our technicians drain, and the car does not need to move to us.
Old Hill: still at the petrol pump?
Then, you could not be in a better place. Keep the car turned off, then ring.