Blackwatertown: Petrol in a Diesel Car? How Worried to Be
Not started? Then less anxious than you likely are. Until your ignition primes your pump, the starter turns, or the vehicle is driven, petrol in a diesel tank just sits there and does no harm. Which makes the honest reply to the first Blackwatertown question — "have I ruined it?" — normally no. To keep it that way, phone Petrol in Diesel then leave the engine alone. What petrol really does to a diesel, how to gauge how far it has travelled, and how to stop it from happening a second time: that is the remainder of this page.
Inside the engine: what petrol in a diesel does
On its way through an engine, diesel does two tasks. Before it burns, it lubricates — and then it burns. Built to very fine clearances, the injectors and your pump depend on your diesel flowing through them to keep their surfaces from wearing against one another.
Of these two tasks, petrol manages the first poorly and the second never. The rattling comes from petrol being made not to ignite when compressed, which is precisely the opposite of what a diesel needs. On top of that it is runnier than diesel, it strips out the lubrication the system rests on, and any pump working on such a mix is wearing itself.
Combined, those make the shape of the trouble clear. Not contact but circulation is what does the harm. A tank with petrol in it is a fuel issue. A pump that has been running on that petrol is the start of a mechanical one, and whatever a worn pump sheds travels on with the fuel to the injectors further on.
Four situations our technicians see in Blackwatertown: how serious is petrol in a diesel?
Filled up, and not started: no case is better. Only the tank has petrol in it, and so the task is emptying your tank and flushing the fuel system where your car sits. This situation can only truly occur on a forecourt: anywhere else, your car got there by being driven.
The ignition switched on, or a short start. With the system primed, the fuel lines and filter now hold petrol that came from the tank. Usually little more than draining, rinsing and sorting your filter, and so still easy.
The pump now spent a couple of miles on diluted fuel — that's what driving it meant. How hard your car was driven matters as much as how far, and this work covers that tank, the fuel lines, the fuel filter and clean fuel through the entire system. Short trips, such as the school run to the local primary school, are one matter. A run as far as Armagh, under 5 miles away, is a very different job. So is any distance on the M77, over 50 miles from Blackwatertown, where the motor has been running hard throughout.
It protested, and only then stopped: smoke, clattering, a throttle gone soft, an idle gone ragged. That is the motor telling you its fuel has stopped behaving like diesel. Pull up wherever you are — the verge on Heugh Road, a lay-by, a side street — then leave the vehicle where it is. What comes first is still the drain and flush, and that deals with it, with permanent damage very uncommon if a vehicle is pulled over soon.
What Blackwatertown people get told about petrol in a diesel — and the stories in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." A fuller tank of the same mixture is all you get, because topping up removes nothing. That guidance presumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A modern diesel sends its fuel through more precise parts at higher pressure, which makes the protection count more, not less.
"It starts, it drives, and so no harm done" — the myth that catches more motorists than any other. Any petrol engine fed diesel usually will not run, and so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally fires up, ticks over and pulls away as if nothing happened — all the while its pump is wearing. A running engine does not mean fine.
Myth: a two-stroke additive lets you to drive home. It was an old workaround, supposed for another fault. That petrol is still inside that tank afterwards, and what it has weakened isn't put back.
"Drain it yourself and you are sorted" — a myth, because after it's been running some petrol sits in the fuel filter and lines, waiting to go right back through your pump on your next start. Emptying petrol into a can at the kerbside is also genuinely dangerous.
Why petrol in a diesel occurs so easily
Carelessness is rarely the cause, and nobody means to do it. 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, whilst a diesel nozzle generally will not go into a petrol motor at all. So the mistake runs one way.
It happens when habit and the car stop matching. Courtesy car, hire car, or a car that's new. Two cars on one driveway, one petrol, one diesel. A forecourt you know, but with its pumps arranged differently. A rushed fill on the way to the nearest station with a train to catch. Years of petrol motors behind you, a diesel Renault Megane in front of you at the forecourt for its first tank — that's when. The hand does what it has always done when you add rain, a phone call or a back seat full of kids.
Blackwatertown motorists: how to prevent petrol in a diesel next time
- Check the pump, not the colour. In the UK unleaded handles are normally green and diesel black, but not on every forecourt. The label is what counts.
- Check your filler flap. Plenty of cars state the fuel type inside the flap or on the cap. Look at it on your first fill in a car you don't know.
- One of each in the home? Label the key to your diesel — a bright fob, a sticker — since intending to remember isn't enough.
- Say it before you lift it. On your first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the petrol pump. It seems silly and it does the trick.
- Put the phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels come with a filler designed to block a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop reading the pump.
- The moment you notice, stop: less petrol in the tank makes a weaker mixture. What to do next doesn't change, though — still don't fire it up.
Blackwatertown: already put petrol in a diesel?
Then the order of things is short. Leave it unstarted, with your ignition off as well. Yet on the forecourt, at the nearest petrol station or anywhere else? Ask the staff to help you roll the vehicle clear of the pump. Next, 0333 366 0103. We'll ask what went in, roughly how much, and if it has been run.
If it was AdBlue and not petrol, say so. That is a separate issue — corrosion and deposits rather than lost protection — and it has its own page for Blackwatertown.
Blackwatertown petrol in a diesel tasks: why one costs more than another
Four different tasks sit behind the four scenarios above — which is why there is no honest single quote. The situation itself does most of the work of moving your cost. Two things follow that: the petrol that went in as a proportion of what your tank takes, then the spot the car is in and whether our van can get to it safely.
What went in, how much, and whether it has run — three questions we ask before costing, not after, for precisely that reason. A range becomes a straight figure once those answers are in.
About Blackwatertown, for a moment
Blackwatertown is a small locality in County Armagh, situated inland at an elevation of 29 metres, approximately 4.7 miles from Armagh city. Blackwatertown has a population of around 638 people, with semi-detached housing being the predominant type. Blackwatertown is close to nearby places such as Benburb, Collegeland, and Charlemont, and is located about 339 miles northwest of London.
Across County Armagh and in Blackwatertown: fuel drain cover
Blackwatertown sits in the BT postcode area, and the vans that answer petrol in diesel call-outs there work the locations around it as well — Benburb, Collegeland and Charlemont among them. You need not bring your car to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
At the petrol pump in Blackwatertown, right now?
Then you are in the best spot there can be. Switched off it remains; then call.