How Worried Should You Be? Petrol in a Diesel Car in Netherburn
If it has not been started, you can worry far less than you likely are. Till your ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the honest reply to that first Netherburn query — "have I ruined it?" — normally no. Leave the engine off and ring Petrol in Diesel — that is how you keep it that way. Below, you will find what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Inside your engine: what petrol in a diesel really does
Two jobs fall to diesel on its journey through a motor. Before it ignites, it lubricates — then it combusts. What keeps the surfaces inside your high-pressure pump and the fuel injectors from wearing against each other is your diesel passing through them — they are built to extremely fine gaps.
Petrol does the first job badly and the second not at all. A pump working on a petrol mixture is wearing itself out, because petrol is thinner than diesel and strips out the protection your fuel system depends on. Petrol is also made to resist igniting under compression — the opposite of what a diesel needs from its fuel — and that's where the knocking comes.
The shape of the trouble is plain once you put those together. Contact doesn't do the damage — circulation does. Where the petrol is only in that tank, it's a problem of fuel, nothing more. The beginning of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
Netherburn, petrol in a diesel: four cases, from mild to significant
Filled up, and not started: nothing beats it. At a forecourt, and truly only there, that petrol is still limited to your tank — since everywhere else the vehicle was driven to reach it. The job is draining and cleaning on the spot.
Your ignition switched on, or a brief start. Petrol has come out of that tank and reached your filter and your lines, since the system has been primed. Still normally straightforward: drain, flush, and the fuel filter seen to.
Those few miles driven meant your pump working on fuel diluted by petrol the whole way. Mileage is only half of it; how hard it was driven matters just as much. Either way this work runs to your tank, the fuel lines, the fuel filter and fresh fuel through the entire circuit. On the school run to the local primary school, the miles is small. Driving as far as Glasgow, under 25 miles away, makes a very different task — as does any distance on the M74, under 3 miles from Netherburn, with your engine labouring hard the whole time.
Driven on until it complained — knocking, smoke, a lumpy idle, a dead throttle. The fuel isn't acting like diesel any more, and the motor is saying so. Leave it where it has stopped: a lay-by, a side street, the verge on Station Road. The drain and flush still go first, and they sort it out: if a vehicle is stopped quickly, long-term damage is very uncommon.
Netherburn people and the petrol in a diesel stories they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Topping up removes nothing; it gives you a bigger tank of the same mix. Percentage is not how a diesel fuel system copes with petrol, however much that advice assumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. More precise parts and higher pressure are the way a modern diesel runs its fuel, and that makes the protection matter more, not less.
This is the one that fools people. Myth: "If it starts and drives, there is no damage done." Feed diesel to a petrol engine and it usually won't 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, which it usually does; meanwhile your pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the car home." It's an old workaround for a distinct issue. That petrol is still in that tank after that, and whatever it has thinned is not put back.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in your filter and lines, ready to go straight back through the pump at the next start. It's also really hazardous to drain petrol into a can at the kerbside.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol motor at all. The forecourt makes it easy, and the error runs one way.
It happens when habit and the vehicle stop matching. Hire cars, courtesy cars, and vehicles that are new to you. A household with one petrol and one diesel on the drive. A familiar forecourt with the pumps in a different order. Fuelling up in a rush en route to Carluke, with a train to catch. A new-to-you diesel Skoda Octavia, its first fuelling, and a motorist accustomed to petrol: exactly when it occurs. Your hand repeats what it has always done when you add rain, a phone call or a back seat full of children.
Netherburn motorists: how to prevent petrol in a diesel next time
- A green handle for unleaded and black for diesel is normal in the UK — but not on every forecourt. Trust the label on the pump, not the colour.
- The first fill in an unfamiliar car is the time to check your filler flap — inside it, or on the cap, plenty of vehicles state which fuel to use.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, in a home with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump. It sounds daft and it works.
- Whilst you're thinking about something else, this is an easy mistake to make — so tuck the phone away.
- Some diesels come with a filler built to refuse a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the petrol pump.
- As soon as you realise, stop: less petrol inside your tank makes a weaker mix. What to do next doesn't change, though — still do not fire it up.
Put petrol in a diesel around Netherburn already?
In that case, there is just a short order of things. Leave it unstarted, with your ignition off as well. Ask the attendants to help you push it clear of the pump if you're still at the forecourt, whether that is JET or anywhere else. Next, 0333 366 0103. We'll ask what went in, about how much, and if it's been run.
Say so if it was AdBlue rather than petrol: it is a separate issue, with its own page for Netherburn, since AdBlue brings corrosion and deposits instead of lost protection.
One petrol in a diesel job around Netherburn costs more than another. Why?
Four different jobs lie behind the four scenarios above — which is why there's no fair single price. Which of them you are in is mostly what moves the cost. Two things come after that: the petrol that went in as a share of what the tank takes, then the spot your car is in and whether our van can get to it safely.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and this is the reason. The replies change a range into a straight figure.
About Netherburn, briefly
Netherburn is a small village situated on the banks of a river in South Lanarkshire, with a mix of rural and residential landscapes. Netherburn has a population of around 525 people and is characterised by predominantly detached housing. Netherburn is located near several other small settlements, including Rosebank, Dalserf, and Tillietudlem, and is approximately 16 miles from Glasgow. Netherburn sits at an elevation of 141 metres above sea level.
Fuel drain cover in Netherburn and across South Lanarkshire
Netherburn sits in the ML postcode area, and the teams that answer petrol in diesel call-outs there work the spots around it as well — Rosebank, Dalserf and Tillietudlem among them. The vehicle does not need to move to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
At the pump around Netherburn, right now?
Then, you couldn't be in a better position. Turned off it remains; then call.