Petrol in a Diesel Car in New Pentland: How Worried Should You Be?
Not started? Then less anxious than you probably are. Petrol resting in a diesel tank does nothing to your engine until something draws it through the fuel system — the ignition priming your pump, your starter, or driving on its own. So the truthful answer to the first query anyone around New Pentland asks, "have I ruined it?", is normally no. Petrol in Diesel is who to ring, with your engine left off, so it remains that way. The remainder of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you again.
The engine and petrol in a diesel: what happens
On its way through an engine, diesel has two tasks. Before it combusts, it lubricates — and then it ignites. Very fine gaps are built into the injectors and the high-pressure pump, and only the diesel flowing through stops their surfaces grinding together.
The second task petrol does not do at all, and the first it does badly. It is runnier than diesel and removes the lubrication your fuel system hinges on, so a pump running on a petrol blend is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That's where the knocking comes from.
Together, those leave the shape of the problem plain. Contact does not do the damage — movement does. Any tank with petrol in it is a fuel fault. The start of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with your fuel to the injectors beyond it.
Petrol in a diesel around New Pentland: how serious is it? Four cases
Filled up, and never started: nothing beats it. The petrol is inside the tank and just the tank, and the task is a drain and a flush where the car stands. This is the one scenario that can only really take place on a forecourt, since anywhere else the car has been driven to get there.
Ignition on, or started for a moment. Petrol has come out of that tank and reached the fuel filter and your lines, because your system has been primed. That's normally still a straightforward job — a drain, a flush, and the filter dealt with.
Driven a couple of miles. Now your pump has spent those miles labouring on thinned fuel. Mileage is only half of it; how hard it was driven matters just as much. Either way the work runs to the tank, your lines, the filter and fresh fuel through the entire system. Driving the kids to the local primary school is one kind of trip. Driving as far as Edinburgh, under 10 miles away, makes a very different job — as does any mileage on the M8, under 10 miles from New Pentland, with the engine running hard all the way.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone ragged. The engine is telling you the fuel is no longer behaving like diesel. Pull up wherever you are — the verge on Dalum Loan, a lay-by, a side street — and leave it where it is. Permanent damage is very rare if a car is stopped early, and the drain and flush-through that still go first take care of it.
Myths New Pentland drivers hear about petrol in a diesel
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A fuller tank of the same mixture is all it gives, since topping up removes nothing. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. A modern diesel runs its fuel through more precise components at higher pressure, which makes the protection count more, not less.
Myth: "If it starts and drives, there's no harm done." This is the one that catches motorists. Any petrol engine fed diesel usually will not run, and so the driver stops and the damage stops with them. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile your pump grinds. Running is not the same as fine.
Myth: a two-stroke additive makes it safe to drive home. It was an old fix, supposed for another issue. The petrol is still in that tank after that, and what it has diluted isn't put back.
Myth: "Drain the tank yourself and you're sorted." After the motor has run, some of the petrol is no longer inside your tank: it is in your filter and the lines, and it goes straight back through your pump at your next start. On top of that, petrol emptied into a can by the road is truly hazardous.
How does petrol in a diesel happen?
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle mostly will not go into a petrol car, but the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake simple, and only in one direction.
When habit and the vehicle stop matching, it happens. A new vehicle, a hire car or a courtesy car. Two vehicles on one driveway, one petrol, one diesel. Your ordinary forecourt, its pumps now in a different order. A hurried fill en route to Eskbank with a train to catch. Precisely the moment it occurs: after years of driving petrol, someone fills a diesel Renault Clio for the first time. Add rain, a phone call or a back seat full of children, and the hand does what it has always done.
How to avoid petrol in a diesel on your next fill-up around New Pentland
- A green handle for unleaded and black for diesel is normal in the UK — yet not on every forecourt. Trust the label on the petrol pump, not the colour.
- Inspect your filler flap. Many motors state the fuel type inside the flap or on the cap. Look at it on your first fill in any car you don't know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, in a house with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new car, say "diesel" aloud. Daft, perhaps, but it works.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Add-on devices exist for cars without one, and some diesels come with a filler that won't take a petrol nozzle. Helpful — but a backstop at best, never a reason to stop checking the label.
- Less petrol makes a thinner mixture, so stop the moment you realise — while remembering that your next step is unchanged. It's still not to crank it.
Petrol already in a diesel in New Pentland? Start here
The order of things is short, then. Leave it unstarted, with your ignition switched off too. Still at the forecourt, at Costco or anywhere else? Ask the staff to help you push the car away from the petrol pump. Phone 0333 366 0103 next, with three facts — your fuel, the rough amount, and whether it's 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 New Pentland.
Why one petrol in a diesel job around New Pentland costs more than another
There's no honest single price for this, since the four situations above are four different tasks. The scenario itself does most of the work of moving your cost. Two things follow that: the petrol that went in as a proportion of what that tank takes, then the spot the vehicle is in and whether a van can get to it safely.
Three queries come first, before quoting, instead of after — what got in, how much, has it run — and this is the reason. The answers turn a range into a straight figure.
About New Pentland itself
New Pentland is a suburban area situated on the riverside in Midlothian, with a mix of flat housing and local amenities. New Pentland sits near the southern edge of Edinburgh, approximately 5 miles from the city centre, and is close to nearby places such as Straiton and Loanhead. New Pentland has a population of around 3301 residents, who enjoy easy access to the surrounding countryside and the nearby city of Edinburgh. New Pentland is located at an elevation of 157 metres above sea level, overlooking the surrounding landscape.
Across Midlothian and in New Pentland: fuel drain cover
The vans answering petrol in diesel call-outs around New Pentland, in the EH postcode area, equally work the places around it, Straiton, Loanhead and Bilston among them. A forecourt, a supermarket car park, a lay-by or your own drive are all locations our technicians drain, and your vehicle doesn't need to come to us.
In New Pentland and still at the petrol pump?
Then you are in the best spot there is. Switched off it remains; then ring.