Hyde: Petrol in a Diesel Car? How Worried to Be
Likely less than you already are — as long as nobody has started the vehicle. Till your ignition primes your pump, your starter cranks, or the car is driven, petrol in a diesel tank just sits there and does no harm. Which makes the truthful reply to the first Hyde question — "have I ruined it?" — usually no. Leave your engine off then ring Petrol in Diesel — that keeps it like that. What petrol really does to a diesel, how to judge how far it's gone, and how to stop it from happening a second time: that's the remainder of this page.
What petrol in a diesel does to the engine
Passing through a motor, diesel does two things at once. Before it ignites, it protects — and then it burns. Built to extremely fine clearances, the fuel injectors and the pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Petrol handles the first job poorly and the second not at all. It is thinner than diesel and strips away the protection your fuel system depends on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is designed to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the rattling comes from.
Seen together, they make clear the shape the trouble takes. It's circulation that causes the harm, not contact. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, borne by your fuel, into your injectors further along, which is why a pump that has worked on the petrol is where a mechanical problem begins.
Four situations our engineers see around Hyde: how bad is petrol in a diesel?
The best case there is: filled up, never started. That petrol is inside your tank and just your tank, and the job is a drain and a flush where the car sits. This is the one situation that can only truly occur on a forecourt, since anywhere else the vehicle has been driven to get there.
A moment's running, or merely your ignition on. Once primed, the fuel system has pulled petrol out of your tank as far as your filter and the lines. Still usually straightforward: drain, flush, and the fuel filter dealt with.
Driven a couple of miles. Now your pump has spent those miles running on diluted fuel. How hard your car was driven counts as much as how far, and the work takes in your tank, your lines, the fuel filter and clean fuel through the whole circuit. On the school run to St Leonard's Church of England Primary Academy, the mileage is short. A run as far as Oxford, under 25 miles away, is a very different job. So is any mileage on the M4, under 5 miles from Hyde, where the motor has been running hard the whole time.
Driven till it complained. Knocking, an uneven idle, smoke, a throttle that has gone soft. The fuel is not behaving like diesel any more, and the engine is saying so. Leave it where it has stopped: a lay-by, a quiet street, the verge on Turnpike Road. A car pulled over quickly very seldom has permanent damage, as the fuel drain and the flush-through, which still come first, deal with it.
Hyde drivers and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing is removed by topping up — you are left with a bigger tank, still the same mix. A diesel fuel system doesn't accept petrol by percentage in the way that guidance assumes.
"Modern diesels can handle a little petrol" — a myth, and nearer the reverse. Lubrication counts more on current diesels, not less, because their fuel runs through finer parts at higher pressure.
One myth that catches motorists off guard: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it usually won't run, and so the motorist stops — and the damage stops with them. While your pump wears, a diesel fed petrol normally starts, idles and drives away as if nothing has happened. Fine and running are not the same at all.
Not so: a two-stroke additive lets you to drive home. It is an old fix, supposed for another fault. What petrol has thinned remains thinned, and that petrol remains in that tank anyway.
"Drain it yourself and you are sorted" — a myth, since after it has been running some petrol sits in your filter and lines, waiting to go right back through your pump on your next start. Also, a can of petrol drained at the roadside is truly dangerous.
Petrol in a diesel: how does it occur?
On purpose? Never. Through carelessness? Rarely, if ever. The petrol nozzle is the narrower of the two and slides 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 routine stops matching the vehicle is the moment it occurs. A new vehicle, a hire car or a courtesy car. A household with one petrol and one diesel on the drive. A well-known forecourt with the pumps in a different order. Racing for a train outside Swindon and fuelling up en route. Years of petrol cars behind you, a diesel BMW 3 Series in front of you at the forecourt for its first tank — that is when. Throw in rain, a phone call or a back seat full of kids, and your hand repeats what it has always done.
Hyde motorists: how to avoid petrol in a diesel next time
- 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.
- Inspect the filler flap. Many motors state the fuel inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- A coloured fob or a sticker on your diesel's key achieves more than any amount of meaning to remember, in a home with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new motor, say "diesel" aloud. Daft, perhaps, but it does the trick.
- Mistakes like this are simple to make while your mind is on something else, and so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for the remainder. Count it as a backstop, then keep reading the pump.
- Stop as soon as you notice. Less petrol in your tank means a weaker mix. It does not change what to do next, which is still not to fire it up.
Put petrol in a diesel in Hyde already?
Short and simple, then, is the order of things. Leave it unstarted, with the ignition off too. If you are still on the forecourt — BP or anywhere else — ask the attendants to help you push it away from the petrol pump. Next, 0333 366 0103. We will ask what went in, roughly how much, and if it's been run.
Say so if it was AdBlue instead of petrol: it is a separate fault, with its own page for Hyde, since AdBlue brings corrosion and deposits rather than lost protection.
Why one petrol in a diesel task in Hyde costs more than another
There is no honest single price for this, since the four situations above are four separate jobs. Which of them you are in is chiefly what shifts your cost. Two things follow that: the petrol that went in as a share of what the tank takes, then the spot the vehicle is in and whether a van can get to it safely.
Three questions come first, before any quote, instead of after — what was put in, how much, has it run — and that is the reason. Their replies are what turn a range into one firm number.
About Hyde and where it is
Hyde is a small hamlet situated on the riverside in Wiltshire, with a mix of detached homes and rural landscapes. Hyde sits at an elevation of 142 metres, surrounded by nearby places such as Groundwell and St Andrews Ridge. Hyde is located near the city of Oxford, approximately 24.6 miles away, and is about 71.4 miles from London. Hyde has a population of around 552 residents, living in predominantly detached housing.
Fuel drain cover across Wiltshire, Hyde included
Hyde rests in the SN postcode area, and the vans that answer petrol in diesel call-outs there work the places around it as well — Groundwell, St Andrews Ridge and Broadbush among them. Our technicians drain wherever your car is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it does not have to come to us.
In Hyde and still at the petrol pump?
Then, you could not be in a better spot. Keep it off. Ring.