How Worried Should You Be? Petrol in a Diesel Car in Leatherhead
Provided it has not been started, worry less than you likely are. Until the ignition primes your pump, your starter turns, or your vehicle is driven, petrol in a diesel tank simply rests there and does nothing. Which means the honest reply to the first Leatherhead query — "have I ruined it?" — normally no. Petrol in Diesel is who to call, with your engine kept off, and so it stays that way. What petrol actually does to a diesel, how to gauge how far it has gone, and how to keep it from happening a second time: that is the remainder of this page.
Inside your engine: what petrol in a diesel really does
Passing through a motor, diesel is doing two things at the same time. Before it ignites, it lubricates — then it combusts. Designed to very fine tolerances, your injectors and the pump depend on your diesel flowing through them to keep their surfaces from wearing against one another.
Of those two tasks, petrol handles the first badly and the second never. It is thinner than diesel and takes away the lubrication the fuel system rests on, and so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the opposite of what a diesel needs from its fuel. That is where the clattering comes from.
Put those together and the shape of the trouble is plain. Not contact but circulation is what does the damage. A tank with petrol in it is a fuel issue. The start of a mechanical problem is a pump that has been labouring on that petrol — and whatever a worn pump sheds moves on with your fuel to the injectors downstream.
Four scenarios we see around Leatherhead: how bad is petrol in a diesel?
Filled up, and not started: no case is better. The petrol is in that tank and only that tank, and the job is a drain and a flush where the vehicle sits. This is the one scenario that can only really happen on a forecourt, because anywhere else the vehicle has been driven to get there.
The ignition turned on, or a short start. Once primed, the system has drawn petrol from that tank up to the fuel filter and your lines. Drain, flush, see to the filter: still usually simple.
Driven a few miles. Now your pump has spent those miles working on thinned fuel. Miles is only half of that; how hard it was driven matters equally. Either way the work includes the tank, your lines, your filter and clean fuel through the whole circuit. On the school run to Leatherhead Trinity School and Nursery, the distance is small. Driving as far as Westminster, under 25 miles away, makes a very different task — as does any distance on the M25, under a mile from Leatherhead, with the motor labouring hard the whole time.
It complained, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone uneven. That's the motor telling you its fuel no longer is behaving like diesel. Whether it is the verge on Bull Hill, a lay-by or a side road, stop where you are then leave it. What comes first is still the fuel drain and flush-through, and that sorts it out, with long-term damage very uncommon if a vehicle is stopped early.
Petrol in a diesel myths Leatherhead motorists hear
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing comes out when you top up — the tank simply carries more of the same mixture. That advice presumes a diesel fuel system handles petrol by percentage. It does not.
Myth: "A newer diesel can cope with a bit of petrol." If anything, the reverse. At higher pressure, through more precise components: that's how a modern diesel moves its fuel, and so the lubrication counts more, not less.
This is the one that fools drivers. Myth: "If it starts and drives, there is no damage done." Any petrol engine fed diesel normally won't run, so the driver stops and the harm stops with them. Feed petrol to a diesel and it normally fires up, ticks over and pulls away as if nothing has happened — all the while its pump is wearing. A running engine does not mean fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a distinct issue. That petrol is still in the tank afterwards, and whatever it has diluted isn't put back.
"Drain it yourself and you're sorted" — a myth, because after it's been running some petrol sits in your filter and lines, waiting to go right back through the pump at your next start. Also, a can of petrol drained by the roadside is truly dangerous.
Why petrol in a diesel happens at all
On purpose? Never. Through carelessness? Rarely, if ever. One way only, because of the nozzles: the slimmer petrol one slides inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol motor. That is how the forecourt makes it straightforward.
The moment routine stops matching your car is the moment it takes place. Courtesy car, hire car, or a vehicle that's new. A household with one petrol and one diesel on the drive. The pumps in a different order on a familiar forecourt. Filling up in a rush on the way to the nearest station, with a train to catch. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Renault Megane for the first time. The hand repeats what it has always done once you add rain, a phone call or a back seat full of children.
Avoiding petrol in a diesel next time you fill up in Leatherhead
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the petrol pump's label; the colour is just a hint.
- The first fill in a strange vehicle is the time to check your filler flap — inside it, or on the cap, many motors state the fuel they take.
- Label your key. In a home with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of intending to remember.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- While you're thinking about something else, this is an easy mistake to make — so put your phone away.
- Some diesels come with a filler designed to block a petrol nozzle, and devices you can add exist for motors without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the pump.
- Less petrol makes a weaker mix, so stop the moment you notice — though remembering that your next stage is unchanged. It's still not to crank it.
Put petrol in a diesel around Leatherhead already?
Then, there's only a short order of things. Starting it is out, and so is turning on the ignition. The attendants on the forecourt — whether at BP itself or wherever you filled up — will usually help push it clear of the pump if you ask. What was put in, roughly how much, and whether it's run: tell us those when you phone 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a different fault — corrosion and deposits rather than lost lubrication — and it has its own page for Leatherhead.
Why one petrol in a diesel job in Leatherhead costs more than another
The four scenarios above are four different tasks, so no single quote for this would be honest. Which of them you are in is mostly what shifts your cost. The ratio matters next, meaning how much of that tank is petrol, and then the location of the car and whether getting to it is safe for a technician.
Three queries come first, before any quote, instead of after — what went in, how much, has it run — and this is the reason. The answers turn a range into a straight figure.
About Leatherhead itself
Leatherhead is a town in Surrey, situated on the River Mole at an elevation of around 45 metres. Leatherhead lies approximately 17 miles south of central London, with good transport links to the city. Leatherhead has a mix of housing types, but is predominantly composed of flats, and is surrounded by areas such as Fetcham Grove and Leatherhead Common. Leatherhead is a significant settlement in the area, with a population of around 13,500 people.
Fuel drain cover across Surrey, Leatherhead included
The teams answering petrol in diesel call-outs around Leatherhead, in the KT postcode area, equally work the locations near it, Fetcham Grove, Hawks Hill and Leatherhead Common included. A forecourt, a supermarket car park, a lay-by or your own drive are all spots we drain, and the car doesn't need to move to us.
In Leatherhead and still at the petrol pump?
Then you are in the best spot there is. Leave it switched off, then ring.