How Worried Should You Be? Petrol in a Diesel Car in Whitley
Less than you likely are, if it has not been started. Till the ignition primes your pump, the starter cranks, or the vehicle is driven, petrol in a diesel tank just waits there and does no harm. Which makes the honest reply to the first Whitley query — "have I ruined it?" — usually no. Petrol in Diesel is who to phone, with the motor left off, and so it remains that way. Further down, you will find what petrol actually does inside a diesel, how far it may have got, and how to stop it happening to you a second time.
Inside the engine: what petrol in a diesel does
Two tasks fall to diesel on its route round a motor. Oiling comes before burning; it does both. Made to very fine tolerances, your injectors and your pump depend on the diesel flowing through them to stop their surfaces wearing against one another.
The second job petrol does not do at all, and the first it does poorly. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is thinner than diesel, it strips out the lubrication your system depends on, and any pump running on such a mix is wearing itself.
Together, those make the shape of the issue plain. The harm is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. A pump that has been labouring on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on.
How serious is petrol in a diesel? Four scenarios our technicians see in Whitley
Fuelled, and not started: no case is better. Being on a forecourt is what makes this the case: elsewhere, the car has been driven there to begin with. With the petrol held inside the tank alone, it is emptied and purged right where it stands, and nothing more is needed.
Started for a second, or just the ignition on. Petrol has come out of the tank and got to your filter and your lines, because your system has been bled. That's usually still a simple task — a drain, a flush, and the fuel filter dealt with.
Some miles driven, and your pump has spent each of them labouring on weakened fuel. Mileage is only half of it; how hard it was driven matters just as much. Either way this work runs to the tank, the lines, your filter and fresh fuel through the whole system. Short trips, like the school run to Whitley Abbey Primary School, are one matter. Very different once more: a run to Coventry, under 3 miles away, or some mileage on the M69, under 5 miles from Whitley, where your engine never stopped running hard.
Clattering, an uneven idle, smoke, a throttle gone soft: driven till it complained. The engine is telling you the fuel is no longer behaving like diesel. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on London Road. Permanent damage is very rare when a vehicle is stopped quickly, and the fuel drain and flush-through that still go first deal with it.
What Whitley motorists get told about petrol in a diesel — and the myths in it
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing comes out when you top up — that tank simply carries more of the same blend. Percentage isn't how a diesel fuel system tolerates petrol, however much that guidance presumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Lubrication counts more on modern diesels, not less, since their fuel runs through smaller components at higher pressure.
"It starts, it drives, so there is no harm" — the myth that catches most people than any other. The driver of a petrol engine fed diesel normally stops, since it will not run, and the damage stops with them. Feed petrol to a diesel and it generally fires up, idles and drives away as if nothing has happened — all while its pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the vehicle home." It is an outdated workaround for a separate fault. The petrol is still in that tank afterwards, and whatever it has diluted isn't put back.
Myth: "Drain that tank yourself and you're sorted." After your engine has been run, some of that petrol is no longer inside that tank: it's in the filter and your lines, and it goes straight back through the pump on your next start. Clearing petrol into a can by the kerbside is also truly hazardous.
Petrol in a diesel: how does it occur?
Carelessness is seldom the cause, and no one means to do it. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, whilst a diesel nozzle generally won't go into a petrol vehicle at all. So the slip runs one way.
Habit and the car getting out of step is how it happens. Hire cars, courtesy cars, and vehicles that are new to you. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. Rushing for a train at Coventry and fuelling up en route. A new-to-you diesel BMW 3 Series, its first fuelling, and a driver used to petrol: precisely when it takes place. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
Next time you fill up around Whitley: preventing petrol in a diesel
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what counts.
- In a motor you do not know, look inside the flap over the filler or at the cap before your first fill: many cars print the fuel there.
- One of each in the house? Mark your key to your diesel — a bright fob, a sticker — because intending to remember is not enough.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It seems silly and it works.
- Mistakes like this are easy to make while your mind is on something else, so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to reject a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, and keep reading the pump.
- The moment you realise, stop: less petrol in the tank makes a weaker blend. What to do next does not change, though — still don't crank it.
Already put petrol in a diesel around Whitley?
The order of things is brief, then. Leave it unstarted, with your ignition off as well. Ask the attendants to help you roll it clear of the pump if you are still on the forecourt, whether that's Asda or anywhere else. Next, 0333 366 0103. We'll ask what went in, about how much, and if it has been run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol means lost protection. So if it was AdBlue, say so — and see its own Whitley page.
One petrol in a diesel task around Whitley costs more than another. Why?
The four situations above are four separate tasks, so no single quote for this would be honest. Mostly, the cost moves with which situation you are in. Two things follow that: the petrol that went in as a proportion of what that tank holds, then the spot your car is in and whether a technician can reach it safely.
Three queries come first, before any quote, instead of after — what went in, how much, has it run — and this is the reason. With those replies, you get a straight figure instead of a range.
About Whitley, briefly
Whitley is a suburban area in the West Midlands, situated near the River Sherbourne at an elevation of around 80 metres. Whitley lies close to the city of Coventry, with nearby neighbourhoods including Pinley and Stoke Aldermoor. Whitley has a mix of housing types, although terraced houses are predominant in the area. Whitley is located approximately 83.9 miles northwest of London.
Fuel drain cover in Whitley and across West Midlands
Petrol in diesel call-outs around Whitley — part of the CV postcode area — go to vans that also cover the locations around it, Pinley, Pinley Gardens and Stoke Aldermoor included. The car does not need to come to us: our engineers drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Whitley: still at the pump?
Nothing beats it: that's where you now are. Switched off it remains; then ring.