Moor Row: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you likely are. Till your ignition primes the pump, the starter turns, or the vehicle is driven, petrol in a diesel tank just waits there and does nothing. Which makes the honest reply to the first Moor Row query — "have I wrecked it?" — normally no. To keep the vehicle that way, phone Petrol in Diesel and leave the engine alone. The rest of this page sets out what petrol actually 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.
What petrol in a diesel does to the motor
On its way through a motor, diesel does two jobs. Lubricating comes before burning; it does both. Built to very fine clearances, the injectors and the pump rely on the diesel moving through them to stop their surfaces wearing against one another.
Of these two jobs, petrol manages the first badly and the second never. A pump working on a petrol blend is wearing itself out, since petrol is thinner than diesel and takes away the lubrication the fuel system relies on. Petrol is also designed to resist igniting under compression — the opposite of what a diesel wants from its fuel — and that is where any rattling comes.
Seen together, they make clear the shape the issue has. Not contact but movement is what causes the damage. A tank with petrol in it is a fuel issue. Whatever a worn pump sheds goes on, borne by the fuel, into the fuel injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault starts.
Petrol in a diesel in Moor Row: how bad is it? Four situations
Filled up, and not started: no case is better. On a forecourt, and really only there, the petrol is still limited to your tank — since everywhere else the vehicle was driven to reach it. The job is emptying and rinsing on the spot.
Ignition on, or started for a moment. Petrol has come out of the tank and got to your filter and the fuel lines, because the system has been bled. Still normally straightforward: drain, flush, and the fuel filter dealt with.
Your pump has spent a few miles on thinned fuel — that's what driving the vehicle does. The work is your tank, the fuel lines, the filter and clean fuel through the entire circuit, and how hard the vehicle was driven matters as much as how far. On the school run to Moor Row Community Primary School, the mileage is short. Very different a second time: a run to Carlisle, under 50 miles away, or any miles on the M6, under 50 miles from Moor Row, where the engine kept labouring hard.
Driven on until it protested — clattering, smoke, a lumpy idle, a dead throttle. The fuel is not acting like diesel any more, and your engine is saying so. Leave it wherever it stops: a lay-by, a quiet street, the verge on Church Street. The drain and flush still come first, and they deal with it: if a vehicle is stopped soon, lasting damage is very uncommon.
Moor Row drivers and that petrol in a diesel myths they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. A fuller tank of the same mix is all it gives, because topping up removes nothing. That advice presumes a diesel fuel system tolerates petrol by percentage. It doesn't.
If anything, the reverse is true. Myth: "A current diesel can cope with a bit of petrol." A modern diesel runs its fuel through finer components at higher pressure, which makes the protection count more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools motorists. Feed diesel to a petrol engine and it usually won't run, and so the motorist stops — and the harm stops with them. Feed petrol to a diesel and it generally fires up, ticks over and drives away as if nothing happened — all the while its pump wears. Fine and running aren't the same at all.
Myth: "Add some two-stroke oil and drive the vehicle home." It's an old workaround for a distinct problem. None of what petrol weakened gets put back by it — and later, the tank still contains the petrol.
If your engine has been run, part of the petrol is in the fuel filter and the lines, not your tank — and the next start sends it straight back through your pump. So the myth "drain the tank yourself and you're sorted" doesn't stand up. Draining petrol into a can by the roadside is also genuinely dangerous.
How petrol ends up: petrol in a diesel
On purpose? Never. Through carelessness? Seldom, if ever. A diesel nozzle generally will not go into a petrol motor, but the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and just in one direction.
The moment habit stops matching the vehicle is the moment it takes place. A car that is new to you — a hire car, on loan as a courtesy car, or brand new. One petrol and one diesel on the driveway of the same household. Your usual forecourt, its pumps now in a different order. A rushed fill on the way to Corkickle with a train to catch. Years of petrol cars behind you, a diesel Renault Clio in front of you on the forecourt for its first tank — that is when. Add a back seat full of kids, a phone call or rain, and the hand takes over.
Preventing petrol in a diesel next time you fill up around Moor Row
- Green for unleaded and black for diesel is normal in the UK — but not on each forecourt. Go by the label on the petrol pump, not the colour.
- The first fill in an unfamiliar vehicle is the time to check your filler flap — on it, or on the cap, plenty of motors state the fuel they take.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of intending to remember, in a home with one of each.
- "Diesel", aloud, before you lift the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Tuck your phone away. This is an easy mistake to make whilst you're thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to block a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a weaker mixture, so stop as soon as you notice — while remembering that the next stage is unchanged. It is still not to crank it.
Petrol already in a diesel in Moor Row? Start here
In that case, there is just a short order of things. Leave it unstarted, with the ignition off too. Ask the staff to help you roll it clear of the petrol pump if you are still on the forecourt, whether that's Texaco or somewhere else. What went in, roughly how much, and if it's run: tell us those when you call 0333 366 0103.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Moor Row page.
One petrol in a diesel task in Moor Row costs more than another. Why?
There is no honest single quote for this, because the four scenarios above are four separate tasks. The scenario itself does most of the work of moving your cost. Where the vehicle is matters too, and whether a technician can safely get to it, after the proportion of petrol to what that tank takes.
Ahead of any quote, not after, come three questions: your fuel that got in, the volume, and whether it has run. That's why. Their answers are what turn a range into one firm number.
About Moor Row, briefly
Moor Row is a small village in Cumbria, situated on the riverside at an elevation of 79 metres, with terraced housing being the predominant type of accommodation. Moor Row lies near the villages of Cleator, Woodend, and Cleator Moor, and is approximately 35.6 miles from the city of Carlisle. Moor Row has a population of around 620 residents, and its location in the north west of England makes it a relatively remote community. Moor Row is also some distance from the capital, being around 251.5 miles from London.
Across Cumbria and in Moor Row: fuel drain cover
The teams answering petrol in diesel call-outs in Moor Row, in the CA postcode area, also work the spots around it, Cleator, Woodend and Cleator Moor included. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our engineers work, and the vehicle doesn't need to move to us.
Moor Row: still at the pump?
No position is better: that's where you now are. Turned off it remains; then call.