How Worried Should You Be? Petrol in a Diesel Car in St James
Probably less than you are now — provided no one has started the car. Until the ignition primes your pump, your starter turns, or the vehicle is driven, petrol in a diesel tank simply rests there and does no harm. Which makes the honest reply to that first St James question — "have I wrecked it?" — normally no. Petrol in Diesel is who to call, with your motor kept off, and so it remains that way. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has got, and the way to make sure you don't repeat it.
What petrol in a diesel does to the motor
Two tasks fall to diesel on its journey round a motor. Lubricating comes before burning; it does both. Made to very fine clearances, your injectors and your pump rely on the diesel flowing through them to stop their surfaces wearing against one another.
Petrol handles the first job badly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on that mixture wearing itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the knocking.
Put these together and the shape of the trouble is clear. The harm is done by movement, not by contact. A tank with petrol in it is a fuel problem. Once the pump has been labouring on that petrol, a mechanical issue has started: whatever is shed by a pump that's wearing down is carried downstream to the injectors with the fuel.
How serious is petrol in a diesel? Four situations we see around St James
The best case there can be: filled up, not once started. At a forecourt, and really only there, the petrol is still limited to your tank — since anywhere else your car was driven to reach it. The task is emptying and flushing on the spot.
Started for a second, or just your ignition on. The fuel system has been bled, so petrol has left that tank and reached the fuel filter and your lines. Still generally easy: drain, flush, and the filter sorted.
Driven a few miles. Now the pump has spent those miles labouring on weakened fuel. The work is your tank, the lines, the filter and fresh fuel through the entire circuit, and how hard the car was driven counts as much as how far. Driving the children to Stoke Hill Infant and Nursery School is one sort of trip. Very different again: a run to Exeter, under a mile away, or any distance on the M5, under 3 miles from St James, where the engine never stopped running hard.
It complained, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone ragged. The motor is telling you your fuel is no longer behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Prospect Park. What goes first is still the drain and flush-through, and that sorts it out, with long-term damage very rare if a car is pulled over quickly.
St James motorists and the petrol in a diesel stories they hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed when you top up — your tank simply holds more of the same mixture. Percentage isn't how a diesel fuel system copes with petrol, whatever that guidance presumes.
"Current diesels can handle a little petrol" — a myth, and nearer the reverse. Smaller parts and higher pressure are the way a modern diesel runs its fuel, and that makes the lubrication count more, not less.
This is the one that fools motorists. Myth: "If it starts and drives, there is no harm done." Any petrol engine fed diesel usually won't run, and so the motorist stops and the harm stops with them. A diesel fed petrol usually starts, idles and drives away as though nothing has happened, whilst your pump wears. Running isn't the same as fine.
An outdated fix for a separate problem is behind this one. Myth: "Add some two-stroke oil and drive it home." The petrol is still inside the tank after that, and whatever it has thinned is not put back.
If the engine has been run, part of that petrol is in the fuel filter and your lines, not your tank — and the next start sends it right back through the pump. So the myth "drain that tank yourself and you are sorted" does not stand up. It's also genuinely hazardous to drain petrol into a can at the roadside.
How petrol ends up: petrol in a diesel
No one does it on purpose, and it is rarely carelessness. The petrol nozzle is the smaller of the two and slips into a diesel filler with almost no resistance; a diesel nozzle generally won't go into a petrol vehicle at all. The forecourt makes it easy, and the error runs one way.
The moment habit stops matching the vehicle is the moment it occurs. A car that is new to you — a hire car, on loan as a courtesy car, or just bought. Households running one of each, petrol and diesel. Your normal forecourt, its pumps now in a different order. Fuelling up in a hurry on the way to St James' Park, with a train to catch. Years of petrol motors behind you, a diesel Renault Megane in front of you on the forecourt for its first tank — that is when. Throw in a back seat full of kids, a phone call or rain, and habit takes over.
Next time you fill up in St James: preventing petrol in a diesel
- A green handle for unleaded and black for diesel is usual in the UK — yet not on every forecourt. Trust the label on the pump, not the colour.
- Check your filler flap. Many vehicles state the fuel inside the flap or on the cap. Look at it on your first fill in a vehicle you do not know.
- Label the key. In a household with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Tuck the phone away. This is an easy mistake to make while you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler built to refuse a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the petrol pump.
- Noticing it halfway? Stop at once. A thinner mixture results from less petrol in your tank, but the next step remains the same: do not crank it.
Already put petrol in a diesel around St James?
Then the order of things is short. Leave it unstarted, with the ignition switched off as well. Ask the attendants to help you roll it clear of the petrol pump if you're still at the forecourt, whether that's Morrisons or anywhere else. Next, 0333 366 0103. We'll ask what got in, roughly how much, and if it has been run.
Corrosion and deposits are the trouble with AdBlue, whereas petrol brings lost lubrication. So if it was AdBlue, say so — and see its own St James page.
St James petrol in a diesel tasks: why one costs more than another
Four different jobs lie behind the four situations above — which is why there's no fair single quote. The scenario itself does most of the work of moving your cost. Two things follow that: the petrol that was put in as a proportion of what the tank holds, then the spot your car is in and whether a technician can reach it safely.
What got in, how much, and if it's run — three queries we ask before costing, not after, for exactly that reason. The replies change a range into a straight figure.
About St James, briefly
St James is a suburban area located near the city of Exeter in Devon, sitting at an elevation of around 55 metres above sea level. St James is characterized by its predominantly terraced housing and is situated close to nearby places such as Polsloe Priory and Pennsylvania. St James is a relatively densely populated area with a population of approximately 13904 residents. St James is also close to the suburb of Polsloe, with which it shares some local amenities.
Fuel drain cover across Devon, St James included
St James waits in the EX postcode area, and the teams that answer petrol in diesel calls there work the places near it as well — Polsloe Priory, Polsloe and Pennsylvania among them. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our technicians drain, and your car doesn't need to move to us.
St James: still at the petrol pump?
In that case, you couldn't be in a better place. Keep the car switched off, then ring.