Priors Marston: Petrol in a Diesel Car? How Worried to Be
Probably less than you are now — as long as nobody has started it. Petrol resting in a diesel tank does nothing to your engine till something pulls it through the fuel system — the ignition priming the pump, the starter, or driving itself. So the fair answer to the first query everyone around Priors Marston asks, "have I ruined it?", is usually no. Keep it like that: leave your engine off and ring Petrol in Diesel. The rest 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 does not happen to you a second time.
The engine and petrol in a diesel: what happens
Passing through an engine, diesel does two things at the same time. Lubricating comes before burning; it does both. Extremely fine tolerances are built into the injectors and the high-pressure pump, and only your diesel flowing through keeps their surfaces from grinding together.
Badly at the first, not at all at the second: that is petrol. The clattering comes from petrol being made not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the lubrication the system depends on, and any pump working on that blend is wearing itself.
Taken together, they make clear what shape the problem takes. Not contact but circulation is what does the damage. All a tank with petrol in it amounts to is a fuel problem. Whatever a worn pump sheds goes on, carried by the fuel, into your injectors downstream, which is why a pump that has been working on that petrol is where a mechanical issue begins.
Four situations our technicians see around Priors Marston: how bad is petrol in a diesel?
Filled up, and never started: no case is better. On a forecourt, and really only there, the petrol is still confined to the tank — because anywhere else the vehicle was driven to get to it. The task is emptying and flushing on the spot.
Ignition on, or started for a second. Petrol has come out of your tank and got to the fuel filter and the fuel lines, because the fuel system has been primed. Drain, flush, see to the filter: still normally simple.
Those few miles driven meant the pump working on fuel weakened by petrol throughout. Mileage is only half of it; how hard it was driven counts equally. Either way the work runs to your tank, the lines, the filter and clean fuel through the entire circuit. On the school run to The Priors School, the distance is short. Very different a second time: a run to Coventry, under 25 miles away, or some mileage on the M40, under 10 miles from Priors Marston, where the engine kept working hard.
Driven on till it complained — clattering, smoke, a ragged idle, a dead throttle. What you are hearing is the motor reporting fuel that no longer behaves like diesel. Pull up where you are — on the verge on Holly Bush Lane, at the kerb, down a side road — and do not move it. Permanent damage is very unusual if a vehicle is pulled over early, and the fuel drain and flush that still go first take care of it.
Myths Priors Marston people hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. A bigger tank of the same mix is all it gives, since topping up removes nothing. That advice supposes a diesel fuel system handles petrol by percentage. It does not.
Myth: "A modern diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel runs its fuel through more precise components at higher pressure, which makes the lubrication count more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that catches people. Any petrol engine fed diesel normally will not run, so the motorist stops and the damage stops with them. While the pump wears, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Being able to run is not the same as being fine.
An old workaround for a separate issue lies behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." The petrol is still in the tank afterwards, and what it has diluted isn't put back.
Myth: "Drain the tank yourself and you are sorted." Once your engine has been run, some of the petrol is no longer in that tank: it's in your filter and the fuel lines, and it goes right back through your pump on your next start. Also, a can of petrol drained by the kerbside is truly risky.
Petrol in a diesel: how does it occur?
No one does it on purpose, and it is seldom carelessness. The petrol nozzle is the slimmer of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally will not go into a petrol motor at all. The forecourt makes it easy, and the mistake runs one way.
It takes place when habit and the vehicle stop matching. Courtesy car, hire car, or a car that is brand new. One petrol and one diesel on the driveway of the same household. A well-known forecourt with the pumps in a different order. A hurried fill on the way to Long Buckby with a train to catch. The first fill-up in a diesel Renault Clio after years of driving petrol is exactly the moment it occurs. Throw in a back seat full of children, a phone call or rain, and the hand takes over.
Priors Marston drivers: how to avoid petrol in a diesel next time
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Check the pump's label; the colour is just a clue.
- The first fill in a new motor is the time to check your filler flap — on it, or on the cap, plenty of cars state which fuel they take.
- One of each in the home? Label the key to the diesel — a coloured fob, a sticker — since meaning to remember isn't enough.
- 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 seems silly and it does the trick.
- Put the phone away. This is an easy mistake to make whilst you are thinking about something else.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for the rest. Treat it as a safety net, and keep reading the petrol pump.
- Stop the moment you realise. Less petrol inside that tank means a weaker mixture. It doesn't change what to do next, which is still not to start the vehicle.
Priors Marston: already put petrol in a diesel?
Short and simple, then, is the order of things. Starting it is out, and so is switching on the ignition. Still at the forecourt, at Texaco or anywhere else? Ask the staff to help you push the car away from the pump. Then call 0333 366 0103 and tell us what was put in, roughly how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate fault — Priors Marston has a page all for it.
What makes one Priors Marston petrol in a diesel task cost more than the next
Four separate jobs sit behind the four scenarios above — which is why there is no honest single quote. Chiefly, the cost shifts with which situation you're in. The share matters next, meaning how much of the tank is petrol, and then the location of the car and whether reaching it is safe for a van.
That is why our technicians ask three queries before quoting rather than after: what was put in, how much, and if it has run. Given the replies, there is a straight figure instead of a range.
About Priors Marston, for a moment
Priors Marston is a small village in Warwickshire, situated in the West Midlands region of England, with a population of around 624 people. Priors Marston sits at an elevation of approximately 150 metres, surrounded by rolling countryside and nearby villages such as Hellidon and Marston Doles. Priors Marston is characterised by its predominantly detached housing stock, reflecting its rural setting. Priors Marston is located about 16 miles from Coventry and some 69 miles northwest of London.
Fuel drain cover across Warwickshire, Priors Marston included
Petrol in diesel calls in Priors Marston — part of the CV postcode area — go to vans that likewise cover the spots about it, Hellidon, Marston Doles and Priors Hardwick included. The car doesn't need to come to us: our technicians drain on a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the pump in Priors Marston?
Nothing beats it: that is where you now are. Keep it turned off, then ring.