How Worried Should You Be? Petrol in a Diesel Car in Guide Post
Far less than you likely are, provided it hasn't been started. Everyone around Guide Post starts with "have I wrecked it?", and the honest answer is usually no: petrol left in the tank of any diesel remains harmless till priming, cranking or driving pulls it into the fuel system. Leave the motor off then phone Petrol in Diesel — that is how you keep it like that. The remainder of this page covers what petrol really does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you a second time.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its route through a motor. Oiling comes before burning; it does both. Very fine clearances go into your injectors and the high-pressure fuel pump, and just your diesel running through keeps their surfaces from grinding together.
Of those two tasks, petrol handles the first poorly and the second never. A pump running on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the lubrication your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel wants from its fuel — and that is where the knocking starts.
Combined, those leave the shape of the trouble clear. Not contact but circulation is what does the damage. A tank with petrol in it is a fuel issue. A pump that has been labouring on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the fuel injectors further on.
How serious is petrol in a diesel? Four scenarios our engineers see around Guide Post
The best case there can be: filled up, never started. At a forecourt, and really only there, that petrol is still limited to your tank — because everywhere else the vehicle was driven to reach it. The job is draining and rinsing on the spot.
A brief spell of running, or just your ignition on. The system has been bled, so petrol has left the tank and got to your filter and the lines. Drain, flush, see to your filter: still normally easy.
The pump has spent a few miles on diluted fuel — that's what driving it does. How hard your car was driven matters as much as how far, and this work takes in that tank, the fuel lines, your filter and fresh fuel through the entire circuit. Driving the children to Mowbray Primary School is one sort of trip. A run as far as Newcastle upon Tyne, under 15 miles away, is a very different task. So is any mileage on the A167(M), under 15 miles from Guide Post, where the motor has been labouring hard the whole time.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. That's your engine telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Cleaswell Hill, a lay-by, a side street — and leave the car where it is. Lasting damage is very rare if a car is stopped early, and the drain and flush-through that still come first take care of it.
Petrol in a diesel stories Guide Post people hear
Myth: topping up to full with diesel makes it fine. It doesn't. A fuller tank of the same mixture is all you get, since topping up takes out nothing. That guidance presumes a diesel fuel system handles petrol by percentage. It doesn't.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. At higher pressure, through finer components: that's how a current diesel handles its fuel, so the lubrication matters for more, not less.
"It starts, it drives, and so no harm done" — the myth that trips up most drivers than any other. A petrol engine fed diesel generally will not run, so the motorist stops and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. A running engine doesn't mean fine.
Not so: a two-stroke additive makes it safe to drive home. It was an old workaround, supposed for another fault. It does not put back what petrol has diluted, and the petrol is still inside that tank afterwards.
Once your engine has been run, part of that petrol sits in the fuel filter and your lines, not the tank — and your next start sends it straight back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't hold. Emptying petrol into a can by the roadside is also genuinely dangerous.
Why petrol in a diesel happens so easily
It's rarely carelessness, and no one does it on purpose. The forecourt makes it easy: the petrol nozzle is the smaller of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle generally won't go into a petrol motor at all. So the mistake runs one way.
When habit and the car stop matching, it takes place. Any motor that is new to you — a hire car, on loan as a courtesy car, or brand new. Households running one of each, petrol and diesel. Your normal forecourt, its pumps suddenly in a different order. A train to catch, and a rushed fill on the way to Ashington. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it happens. Add a back seat full of children, a phone call or rain, and the hand takes over.
How to avoid petrol in a diesel on your next fill-up in Guide Post
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, though most generally do. Read the pump's label; the colour is only a clue.
- Check the filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, in a house with one of each.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It seems daft and it works.
- Mistakes like this are straightforward to make whilst your mind is on something else, so your phone goes away.
- Add-on devices exist for motors without one, and some diesels are built with a filler that will not take a petrol nozzle. Helpful — but a backstop only, never a reason to stop checking the label.
- The moment you realise, stop: less petrol in your tank makes a weaker blend. What to do next doesn't change, though — still don't crank it.
Already put petrol in a diesel around Guide Post?
Then the order of things is short. Do not turn your ignition on, and do not start it. If you're still at the forecourt — JET or anywhere else — ask the staff to help you roll it away from the petrol pump. Ring 0333 366 0103 next, with three facts — your fuel, the rough amount, and if it has run.
Corrosion and deposits form the problem with AdBlue, whereas petrol means lost lubrication. So if it was AdBlue, say so — and see its own Guide Post page.
One petrol in a diesel task in Guide Post costs more than another. Why?
A fair single quote doesn't exist here: four situations, four separate jobs. The scenario itself does most of the work of moving your cost. Next it's the share — how much petrol was put in against how much your tank takes — and after that where the car is and whether a technician 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. Given those answers, you get a straight figure instead of a range.
About Guide Post, for a moment
Guide Post is a village in Northumberland, situated on the riverside at a low elevation of around 30 metres. Guide Post lies near the city of Newcastle upon Tyne, approximately 12.6 miles away, and is close to other nearby places such as Sheepwash and Choppington. Guide Post has a population of around 2852 people, predominantly living in semi-detached housing.
Across Northumberland and around Guide Post: fuel drain cover
Sheepwash, Scotland Gate and Choppington are among the places near Guide Post that the same vans work, answering petrol in diesel call-outs across Guide Post's NE postcode area. No need to move your car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all locations we drain.
Still at the pump in Guide Post?
In that case, you couldn't be in a better position. Phone, and keep it turned off.