Staincross: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less worried than you likely feel. Till the ignition primes the pump, your starter cranks, or the car is driven, petrol in a diesel tank simply rests there and does nothing. Which makes the honest reply to that first Staincross query — "have I wrecked it?" — normally no. Leave your engine off then ring Petrol in Diesel — that keeps it that way. Below, you will find what petrol really does inside a diesel, how far it may have gone, and how to stop it happening to you again.
Inside the engine: what petrol in a diesel really does
On its way through an engine, diesel does two jobs. Lubricating comes before burning; it does both. Very fine tolerances are built into the fuel injectors and your high-pressure pump, and only your diesel running through keeps those surfaces from grinding together.
Of those two tasks, petrol handles the first badly and the second not at all. It's thinner than diesel and removes the protection the fuel system depends on, so a pump running on a petrol blend is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That is where the knocking comes from.
Put these together and the shape of the issue is clear. Contact does not do the harm — circulation does. Petrol in a tank is a fuel issue. Whatever a worn pump sheds goes on, borne by your fuel, into the injectors further along, which is why a pump that has been working on that petrol is where a mechanical problem starts.
How bad is petrol in a diesel? Four situations we see in Staincross
The best case there can be: filled up, not once started. Just that tank has petrol in it, and so the job is emptying the tank and flushing the system where your car stands. This situation can only truly occur at a forecourt: anywhere else, your car got there by being driven.
A moment's running, or just the ignition on. Petrol has left your tank and reached the filter and your lines, since the system has been primed. Still usually simple: drain, flush, and your filter dealt with.
The pump has worked a few miles on weakened fuel — that's what driving the car does. How hard your car was driven matters as much as how far, and this work takes in your tank, the lines, the filter and clean fuel through the entire system. On the school run to Mapplewell Primary School, the miles is short. Any miles on the M1, under 3 miles from Staincross, means the motor working hard throughout, and a run to Wakefield, under 10 miles away, is a very different task as well.
Driven on until it protested — knocking, smoke, a ragged idle, a dead throttle. The fuel isn't acting like diesel any more, and your motor is telling you. Whether it is the verge on Spark Lane, a lay-by or a side street, stop where you are then leave it. A car stopped early very seldom has lasting damage, as the drain and the flush, which still come first, take care of it.
Myths Staincross motorists hear about petrol in a diesel
Myth: topping up to full with diesel makes it fine. It does not. Nothing comes out when you top up — that tank simply holds more of the same mixture. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the opposite. Finer components and higher pressure are how a modern diesel runs its fuel, and that makes the protection matter more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. Diesel in a petrol motor normally leaves a motor that won't run: the motorist stops, and so does the damage. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. A running engine doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a separate fault. It does not put back what petrol has diluted, and that petrol is still in that tank afterwards.
The next start sends petrol back round your pump out of the fuel lines and your filter, where some of that ends up after the motor has run. That is why a DIY tank drain does not leave you sorted — a myth. It is also truly hazardous to drain petrol into a can by the roadside.
Petrol in a diesel: how does it happen?
No one does it on purpose, and it's seldom carelessness. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slips into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol motor at all. So the slip runs one way.
The moment habit stops matching the vehicle is the moment it occurs. Courtesy car, hire car, or a vehicle that's new. One petrol and one diesel on the driveway of the same household. Your ordinary forecourt, its pumps now in a different order. A hurried fill on the way to Darton with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a driver used to petrol: exactly when it happens. Add a back seat full of children, a phone call or rain, and habit takes over.
How to avoid petrol in a diesel at your next fill-up around Staincross
- The label is what counts, so read the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- Many vehicles state the fuel type inside the filler flap or on the cap, so check there on the first fill in any motor you don't know.
- A coloured fob or a sticker on the diesel's key achieves more than any amount of meaning to remember, in a home with one of each.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" out loud before you take the nozzle off the pump. It sounds silly and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so tuck the phone away and keep your mind on the pump.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices exist for vehicles without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a weaker mix, so stop the moment you notice — while remembering that the next step is unchanged. It is still not to start the vehicle.
Petrol already in a diesel in Staincross? Start here
Then the order of things is brief. Starting it is out, and so is turning on the ignition. Ask the staff to help you push it clear of the pump if you're still at the forecourt, whether that is Shell or somewhere else. Phone 0333 366 0103 next, with three answers — your fuel, the rough volume, and whether it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a separate issue — Staincross has a page just for it.
One petrol in a diesel task around Staincross costs more than another. Why?
There's no honest single quote for this, since the four situations above are four separate jobs. Which of them you're in is chiefly what moves your cost. The ratio counts next, meaning how much of that tank is petrol, followed by the location of the vehicle and whether getting to it is safe for a van.
What was put in, how much, and whether it's run — three questions we ask before pricing, not after, for exactly that reason. The answers change a range into a straight figure.
About Staincross
Staincross is a village in South Yorkshire, situated inland at an elevation of 101 metres, approximately 6.7 miles from Wakefield. Staincross is characterized by its semi-detached housing and is located near other local places such as Mapplewell, Greenside, and New Lodge. Staincross has a population of around 3389 residents, making it a small but established community in the region.
Fuel drain cover across South Yorkshire, Staincross included
Staincross sits in the S postcode area, and the vans that answer petrol in diesel jobs there work the places around it as well — Mapplewell, Greenside and New Lodge among them. The car doesn't need to move to us: our technicians drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Staincross: still at the petrol pump?
The best position there is, then — that is where you are. Keep the vehicle switched off, then ring.