Winterton: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as no one has started the car. Petrol sitting in a diesel tank does nothing to the engine until something pulls it through the fuel system — your ignition priming your pump, your starter, or driving itself. So the honest answer to the first query anyone in Winterton asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to call, with your motor kept off, and so it stays that way. The remainder of this page sets out what petrol really does to a diesel, how to judge how far it has got, and how to make sure it doesn't happen to you again.
Inside your engine: what petrol in a diesel really does
Two tasks fall to diesel on its route round a motor. Before it ignites, it lubricates — then it burns. Built to extremely fine clearances, the fuel injectors and your pump depend on the diesel moving through them to keep their surfaces from wearing against one another.
Petrol does the first job poorly and the second not at all. It's runnier than diesel and removes the protection the fuel system depends on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the knocking comes from.
Put those together and the shape of the problem is clear. Not contact but movement is what does the harm. All a tank with petrol in it amounts to is a fuel fault. The start of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds moves on with the fuel to your injectors beyond it.
How serious is petrol in a diesel? Four scenarios our technicians see in Winterton
The best case there can be: filled up, not once started. The petrol is in the tank and only your tank, and the job is a drain and a flush where your car sits. This is the one situation that can only really occur on a forecourt, as anywhere else the car has been driven to get there.
Ignition on, or started for a moment. Petrol has come out of your tank and reached the filter and the lines, because your system has been bled. Still usually simple: drain, flush, and your filter dealt with.
Driven a couple of miles. Now your pump has spent these miles working on weakened fuel. The work is that tank, the fuel lines, the fuel filter and fresh fuel through the whole circuit, and how hard the vehicle was driven matters as much as how far. Driving the kids to Winterton Church of England Infants' School is one kind of trip. Any miles on the A1077(M), under 10 miles from Winterton, means the engine has worked hard throughout, and a run to Kingston upon Hull, under 15 miles away, is a very different task as well.
Driven on till it complained — knocking, smoke, an uneven idle, a soft throttle. The fuel isn't behaving like diesel any more, and the engine is saying so. Pull up wherever you are — the verge on High Street, a lay-by, a side street — and leave the vehicle where it is. What comes first is still the fuel drain and flush, and that deals with it, with lasting damage very rare when a car is pulled over early.
Stories Winterton motorists hear about petrol in a diesel
"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 bigger tank, still the same mix. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Protection counts more on modern diesels, not less, since their fuel runs through more precise parts at higher pressure.
This is the one that catches motorists. Myth: "If it starts and drives, there's no harm done." Diesel in a petrol motor normally means a motor that will not run: the driver stops, and so does the damage. While the pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Fine and running are not the same at all.
Myth: a two-stroke additive makes it safe to drive home. It is an old fix, supposed for another issue. What petrol has diluted stays diluted, and that petrol remains in that tank anyway.
"Drain it yourself and you're sorted" — a myth, since after it has been running some petrol sits in your filter and lines, waiting to go right back through your pump at your next start. Emptying petrol into a can by the roadside is also genuinely hazardous.
How does petrol in a diesel happen?
It is rarely carelessness, and no one does it on purpose. The petrol nozzle is the narrower of the two and slips 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 error runs one way.
It occurs when habit and the vehicle stop matching. A new car, a hire car or a courtesy car. Two motors on one driveway, one petrol, one diesel. Your usual forecourt, its pumps suddenly in a different order. Fuelling up in a hurry en route to Brough, with a train to catch. The first fill-up in a diesel BMW 3 Series 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.
Avoiding petrol in a diesel next time you fill up in Winterton
- The label is what counts, and so read the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- Inspect your filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on your first fill in any vehicle you don't know.
- Good intentions count for less than a sticker or a fob in a vivid colour on your diesel's key when a household has one of each. So label it.
- 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 pump. It seems daft and it works.
- Put your phone away. This is an easy mistake to make while you are thinking about something else.
- Add-on devices exist for motors without one, and some diesels are built with a filler that won't accept a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Stop as soon as you notice. Less petrol inside that tank means a weaker mix. It doesn't change what to do next, which is still not to fire it up.
Petrol already in a diesel around Winterton? Start here
The order of things is short, then. Do not switch the ignition on, and do not crank it. Still on the forecourt, at Roxby Road Garage or anywhere else? Ask the attendants to help you push the vehicle away from the pump. Call 0333 366 0103 next, with three facts — the fuel, the rough quantity, and if it has run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost protection, make it a separate issue — Winterton has a page just for it.
What makes one Winterton petrol in a diesel task cost more than the next
Four separate jobs lie behind the four scenarios above — which is why there is no honest single quote. The situation itself does most of the work of moving your cost. Where the car is matters too, and whether a van can safely reach it, after the proportion of petrol to what your tank takes.
That's why our technicians ask three questions before costing rather than after: what was put in, how much, and whether it's run. A range turns into a straight figure once the answers are in.
About Winterton, for a moment
Winterton is a small town on the coast of Lincolnshire, situated near the Humber Estuary at an elevation of around 29 metres. Winterton lies approximately 12 miles from Kingston upon Hull and is surrounded by nearby villages such as Roxby and West Halton. Winterton has a population of around 4764 people, predominantly living in semi-detached housing. Winterton is located about 150 miles north of London, making it a relatively remote coastal town in eastern England.
Across Lincolnshire and around Winterton: fuel drain cover
Roxby, Coleby and West Halton are among the spots around Winterton that the same vans work, answering petrol in diesel calls across Winterton's DN postcode area. Our engineers drain wherever your vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
Still at the petrol pump in Winterton?
Then, you could not be in a better place. Switched off it remains; then ring.