How Worried Should You Be? Petrol in a Diesel Car in Torbay
Provided it has not been started, you can worry less than you likely are. Till the ignition primes the pump, your starter turns, or your vehicle is driven, petrol in a diesel tank just rests there and does nothing. Which means the truthful reply to that first Torbay query — "have I ruined it?" — usually no. Leave your engine off then ring Petrol in Diesel — that is how you keep it that way. Below, this page sets out what petrol really does inside a diesel, how far it might have got, and how to stop it happening to you a second time.
Petrol in a diesel: what does it do to the motor?
Two tasks fall to diesel on its route through a motor. Before it ignites, it lubricates — and then it combusts. The high-pressure pump and the injectors are made to very fine clearances, and the diesel passing through them is what keeps those surfaces from grinding against one another.
Badly at the first, not at all at the second: that is petrol. The knocking 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 out the protection your system depends on, and any pump running on such a mixture is wearing itself.
Combined, those make the shape of the issue plain. Contact doesn't do the damage — circulation does. Where that petrol is only inside the tank, it's a fault of fuel, nothing more. The beginning of a mechanical one is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to your injectors beyond it.
How bad is petrol in a diesel? Four situations our engineers see around Torbay
Fuelled but not once started — as good as it gets. That petrol is inside that tank and only your tank, and the task is a drain and a flush where your car sits. This is the one scenario that can only truly happen on a forecourt, since anywhere else the car has been driven to get there.
A brief spell of running, or merely your ignition on. Petrol has left the tank and got to the filter and your lines, since the system has been bled. Usually nothing more than draining, cleaning and seeing to the fuel filter, and so still simple.
Driven a couple of miles. Now your pump has spent those miles working on diluted fuel. Mileage is only half of it; how hard it was driven counts just as much. Either way this work runs to the tank, your lines, the fuel filter and clean fuel through the entire circuit. Short trips, like the school run to Oldway Primary School, are one matter. A run as far as Exeter, under 25 miles away, is a very different task. So is any mileage on the M5, under 25 miles from Torbay, where your engine has been working hard the whole time.
Driven until it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. The fuel is not acting like diesel any more, and the motor is telling you. Leave it wherever it has stopped: a lay-by, a quiet street, the verge on Promenade. The fuel drain and flush-through still come first, and they take care of it: if a car is stopped soon, permanent damage is very unusual.
What Torbay people get told about petrol in a diesel — and the myths in it
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. A bigger tank of the same mixture is all you get, since topping up takes out nothing. Percentage isn't how a diesel fuel system tolerates petrol, whatever that advice assumes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. A newer diesel runs its fuel through smaller parts at higher pressure, which makes the protection matter more, not less.
One myth that catches people out: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel normally has no choice but to stop, since it will not run, and the damage stops there. A diesel fed petrol normally starts, idles and drives away as if nothing has happened, whilst the pump grinds. Running is not the same as fine.
Not so: a two-stroke additive lets you to drive home. It is an old fix, supposed for another problem. What petrol has diluted stays weakened, and that petrol remains in that tank anyway.
"Drain it yourself and you're sorted" — a myth, since after it's been running some petrol sits in the fuel filter and lines, ready to go right back through the pump on the next start. Draining petrol into a can by the kerbside is also truly dangerous.
How does petrol in a diesel take place?
Nobody does it on purpose, and it's seldom carelessness. A diesel nozzle generally will not fit a petrol motor, yet the narrower petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and just in that direction.
Routine and your car getting out of step is when it happens. Hire cars, courtesy cars, and cars that are new to you. A household with one petrol and one diesel on the drive. Your ordinary forecourt, its pumps suddenly in a different order. A hurried fill en route to Paignton with a train to catch. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver accustomed to petrol: exactly when it occurs. Throw in a back seat full of children, a phone call or rain, and habit wins.
Torbay motorists: how to avoid petrol in a diesel next time
- The label is what matters, and so read the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- In a motor you do not know, look inside the flap over your filler or at the cap before the first fill: plenty of cars print the fuel type there.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key when a house has one of each. So mark it.
- "Diesel", out loud, before you lift the nozzle — each time a new or hired car gets its first tank. It sounds daft. It does the trick.
- Mistakes like this are simple to make whilst your mind is on something else, and so your phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to reject a petrol nozzle, and add-on devices are available for cars without one. They are a safety net, not a reason to stop reading the petrol pump.
- Less petrol means a weaker mixture, so stop the moment you realise — while remembering that the next stage is unchanged. It is still not to fire it up.
Put petrol in a diesel around Torbay already?
Then, there is just a short order of things. Do not start the vehicle, and don't switch the ignition on. The staff on the forecourt — whether at Texaco itself or wherever you filled up — will normally help push it clear of the petrol pump if you ask. Next, 0333 366 0103. We'll ask what got in, about how much, and if it's been run.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and see its own Torbay page.
Torbay petrol in a diesel tasks: why one costs more than another
An honest single price doesn't exist here: four situations, four separate jobs. Mostly, your cost moves with which situation you are in. The proportion matters next, meaning how much of your tank is petrol, and then the location of the car and whether reaching it is safe for a technician.
What was put in, how much, and whether it's run — three questions our technicians ask before pricing, not after, for precisely that reason. A range becomes a straight figure once the answers are in.
About Torbay and its setting
Torbay is a coastal locality in Devon, situated near the towns of Paignton and Preston, with Hollicombe to the north. Torbay has a relatively low elevation of around 3 metres above sea level, reflecting its seaside location. Torbay is characterized by a high proportion of flat housing, which is typical of many coastal areas in the South West. Torbay is approximately 19 miles south of Exeter and around 166 miles west of London.
Across Devon and in Torbay: fuel drain cover
Petrol in diesel call-outs around Torbay — part of the TQ postcode area — go to teams that likewise cover the spots around it, Preston, Hollicombe and Paignton included. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own drive are all places we drain.
Torbay: still at the petrol pump?
The best position there is, then — that's where you are. Leave the vehicle turned off, and ring.