Black Horse Corner: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely are. Petrol sitting in a diesel tank does nothing to the engine until something draws it through the fuel system — your ignition priming the pump, the starter, or driving on its own. So the truthful answer to the first question everyone around Black Horse Corner asks, "have I wrecked it?", is generally no. Petrol in Diesel is who to ring, with your engine left off, and so it stays that way. Read on for three things: the effect petrol has inside a diesel motor, the signs of how far it has got, and the way to make sure you don't repeat it.
Your engine and petrol in a diesel: what goes on
On its way through an engine, diesel does two jobs. It lubricates to begin with, and after that does it burn. Very fine clearances go into the injectors and the high-pressure fuel pump, and only the diesel running through keeps their surfaces from grinding together.
Of those two tasks, petrol manages the first badly and the second not at all. The knocking comes from petrol being designed not to ignite when compressed, which is exactly the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips away the protection the fuel system rests on, and any pump running on that blend is wearing itself.
Put those together and the shape of the issue is clear. The harm is done by circulation, not by contact. Petrol in the tank is a fuel issue. A pump that has been working on that petrol is the start of a mechanical one, and whatever a worn pump sheds moves on with your fuel to the fuel injectors further on.
Four scenarios our technicians see in Black Horse Corner: how serious is petrol in a diesel?
Filled but not once started — as good as it gets. Only the tank has petrol in it, so the job is emptying your tank and rinsing the system where your car sits. This scenario can only truly happen at a forecourt: anywhere else, the car got there by being driven.
Started for a moment, or only the ignition on. The system has been primed, and so petrol has left the tank and reached your filter and the fuel lines. Still normally straightforward: drain, flush, and the filter sorted.
Those few miles on the road were your pump labouring on fuel weakened by petrol throughout. Tank, lines, filter, then clean fuel run through the whole circuit: that is the work, and the way the vehicle was driven matters as much as the mileage. Short trips, such as the school run to Millfields Primary School, are one thing. Getting as far as Colchester, under 5 miles away, makes a very different task — as does any mileage on the M11, under 50 miles from Black Horse Corner, with the engine labouring hard all the way.
Driven on till it protested — rattling, smoke, a ragged idle, a dead throttle. What you are hearing is your motor signalling fuel that no longer behaves like diesel. Stop wherever you are — the verge on Keelars Lane, a lay-by, a side street — and leave the vehicle there. Lasting damage is very unusual when a vehicle is pulled over quickly, and the drain and flush that still go first deal with it.
Petrol in a diesel myths Black Horse Corner drivers hear
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. A bigger tank of the same mixture is all you get, because topping up takes out nothing. The assumption behind that advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Not so: a newer diesel copes with a bit of petrol. Rather, the reverse. A current diesel runs its fuel through finer parts at higher pressure, which makes the protection matter more, not less.
The myth that catches people out: if it starts and drives, it must be unharmed. Diesel in a petrol motor generally means a motor that will not run: the driver stops, and so does the damage. Whilst the pump grinds, a diesel fed petrol usually starts, idles and drives away as if nothing has happened. Fine and running aren't the same at all.
An old workaround for a distinct issue is behind this one. Myth: "Add some two-stroke oil and drive the car home." The petrol is still in that tank afterwards, and what it has thinned is not put back.
Once your engine has been run, part of that petrol sits in the fuel filter and the fuel lines, not that tank — and your next start pulls it right back through the pump. So the myth "drain that tank yourself and you are sorted" doesn't stand up. Clearing petrol into a can by the roadside is also truly hazardous.
How it happens: petrol in a diesel
It's rarely carelessness, and nobody does it on purpose. The forecourt makes it easy: the petrol nozzle is the narrower of the two, and it slips into a diesel filler with almost no resistance, whilst a diesel nozzle generally will not go into a petrol vehicle at all. So the mistake runs one way.
It takes place when habit and the car stop matching. Any vehicle that's new to you — a hire car, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. Your normal forecourt, its pumps now in a different order. Rushing for a train at Wivenhoe and fuelling up en route. A new-to-you diesel Renault Clio, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up in Black Horse Corner
- Not every forecourt in the UK follows green for unleaded and black for diesel, even if most usually do. Check the pump's label; the colour is just a hint.
- In a vehicle you do not know, look inside the flap over the filler or at the cap before the first fill: many cars state the fuel type there.
- Mark the key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- It seems daft and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the pump.
- While you are thinking about something else, this is an easy mistake to make — so put your phone away.
- Add-on devices are available for motors without one, and some diesels come with a filler that will not accept a petrol nozzle. Useful — but a backstop at best, never a reason to stop checking the label.
- Stop as soon as you notice. Less petrol inside your tank makes a thinner blend. It doesn't change what to do next, which is still not to fire it up.
Petrol already in a diesel in Black Horse Corner? Start here
Then the order of things is brief. Leave it unstarted, with your ignition off too. Ask the staff to help you roll it clear of the petrol pump if you're still at the forecourt, whether that's Esso or somewhere else. Next, 0333 366 0103. We will ask what was put in, roughly how much, and if it has been run.
Say so if it was AdBlue instead of petrol: it is a different issue, with its own page for Black Horse Corner, because AdBlue brings corrosion and deposits instead of lost lubrication.
What makes one Black Horse Corner petrol in a diesel job cost more than the next
Four different tasks sit behind the four situations above — which is why there's no honest single quote. Mostly, your cost shifts with which situation you are in. The share matters next, meaning how much of that tank is petrol, and then the location of the vehicle and whether getting to it is safe for our van.
What was put in, how much, and if it's run — three queries our engineers ask before costing, not after, for exactly that reason. Given those answers, there is a straight figure instead of a range.
About Black Horse Corner itself
Black Horse Corner is a small suburban area located near the coast in Essex, with an elevation of 31 metres above sea level. Black Horse Corner sits approximately 3.8 miles from Colchester and is surrounded by nearby places such as Wivenhoe and Elmstead Heath. Black Horse Corner is characterised by its predominantly semi-detached housing stock, reflecting the typical residential development of the region. Black Horse Corner is also within commuting distance to London, being around 53 miles from the capital.
Fuel drain cover around Black Horse Corner and across Essex
Black Horse Corner waits in the CO postcode area, and the teams that answer petrol in diesel call-outs there work the locations around it as well — Wivenhoe, Keelars Tye and Elmstead Heath among them. A forecourt, a supermarket car park, a lay-by or your own drive are all places we drain, and the car doesn't need to come to us.
In Black Horse Corner and still at the pump?
The best position there is, then — that's where you are. Keep it off. Ring.