Longshaw: Petrol in a Diesel Car? How Worried to Be
If it hasn't been started, worry far less than you probably are. Petrol sitting in a diesel tank does nothing to the engine until something pulls it through the system — the ignition priming your pump, the starter, or driving on its own. So the fair answer to the first question anyone in Longshaw asks, "have I ruined it?", is generally no. Petrol in Diesel is who to call, with the engine left off, and so it remains 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 a second time.
What petrol in a diesel does to your engine
Two tasks fall to diesel on its journey through a motor. Lubricating comes before burning; it does both. What stops the surfaces inside the high-pressure pump and the fuel injectors from grinding against each other is the diesel flowing through them — they are built to extremely fine tolerances.
The second task petrol does not do at all, and the first it does poorly. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump running on the blend to wear itself. It's equally made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the rattling.
The shape of the problem is clear once you put those together. Contact doesn't do the damage — movement does. Petrol in the tank is a fuel fault. Whatever a worn pump sheds travels on, carried by your fuel, into the injectors further along, which is why a pump that has worked on that petrol is where a mechanical fault begins.
Petrol in a diesel around Longshaw: how bad is it? Four cases
Fuelled up, never started. The best case there is. The petrol is in your tank and only the tank, and the task is a drain and a flush where the car stands. This is the one scenario that can only really occur at a forecourt, because anywhere else the car has been driven to get there.
Started for a second, or just the ignition on. Petrol has left that tank and reached your filter and your lines, since the fuel system has been primed. That's usually still an easy task — a drain, a flush, and the fuel filter dealt with.
Driven a couple of miles. Now your pump has spent those miles labouring on thinned fuel. The work is the tank, the lines, the filter and fresh fuel through the whole circuit, and how hard the car was driven matters as much as how far. Driving the kids to Longshaw Community Junior School is one kind of trip. Any mileage on the M65, under 3 miles from Longshaw, means the motor has worked hard throughout, and a run to Preston, under 10 miles away, makes a very different task too.
Driven till it protested. Knocking, an uneven idle, smoke, a throttle that has gone soft. The engine is telling you the fuel is no longer behaving like diesel. Whether it is the verge on Snaefell Road, a lay-by or a side street, stop there then leave it. What comes first is still the drain and flush-through, and that deals with it, with permanent damage very unusual when a car is pulled over early.
Myths Longshaw drivers hear about petrol in a diesel
It will not be fine. The myth: "Fill it the rest of the way with diesel and it'll be." Nothing comes out when you top up — your tank simply holds more of the same blend. The assumption behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the opposite holds. Myth: "A newer diesel can cope with a bit of petrol." At higher pressure, through finer components: that is how a modern diesel handles its fuel, so the protection matters more, not less.
The myth that catches motorists out: if it starts and drives, it must be unharmed. A petrol motor fed diesel normally will not run, and so the motorist stops and the damage stops with them. A diesel fed petrol usually starts, ticks over and drives away as if nothing has happened, whilst the pump grinds. A running engine does not mean fine.
An outdated fix for a separate problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." None of what petrol thinned gets put back by it — and afterwards, the tank still holds that petrol.
If the motor has run, part of that petrol sits in your filter and the fuel lines, not that tank — and your next start pulls it right back through your pump. So the myth "drain the tank yourself and you are sorted" does not stand up. It is also genuinely risky to drain petrol into a can at the kerbside.
How does petrol in a diesel take place?
A careless moment is seldom the cause, and nobody means to do it. A diesel nozzle generally will not go into a petrol vehicle, but the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error simple, and only in one direction.
It happens when habit and your car stop matching. Courtesy car, hire car, or a vehicle that is brand new. Two cars on one driveway, one petrol, one diesel. The pumps in a different order on a well-known forecourt. Racing for a train outside Mill Hill (Lancs) and filling up en route. A new-to-you diesel Volkswagen Golf, its first fuelling, and a driver used to petrol: exactly when it happens. With rain, a call coming in, or a car full of children to deal with, the hand just does what it has always done.
Next time you fill up around Longshaw: avoiding petrol in a diesel
- Read the pump, not the colour. In the UK unleaded handles are usually green and diesel black, yet not on every forecourt. The label is what counts.
- The first fill in a new car is the time to check the filler flap — inside it, or on the cap, many vehicles state the fuel they take.
- A coloured fob or a sticker on your diesel's key does more than any amount of intending to remember, for a home with one of each.
- Before the nozzle leaves the petrol pump the first time you fuel a hired or new vehicle, say "diesel" out loud. Silly, yes, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, and so your phone goes away.
- Some diesels come with a filler built to block a petrol nozzle, and devices you can add are available for motors without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the pump.
- Spotting it mid-fill? Stop there and then. A thinner mixture follows from less petrol in that tank, yet the next stage stays the same: don't fire it up.
Petrol already in a diesel around Longshaw? Start here
In that case, there's only a short order of things. Never start the car, and don't switch your ignition on. If you're still at the forecourt — Texaco or anywhere else — ask the staff to help you roll it clear of the petrol pump. Then phone 0333 366 0103 and tell us what got in, about how much, and whether it's run.
AdBlue, not petrol? Then tell us. Corrosion and deposits, not lost lubrication, make it a separate problem — Longshaw has a page all for it.
Why one petrol in a diesel task in Longshaw costs more than another
The four scenarios above are four different jobs, so no single price for this would be honest. The scenario itself does most of the work of moving your cost. Two things come after that: the petrol that got in as a share of what your tank holds, then the place the car is in and whether a van can reach it safely.
Three questions come first, before quoting, instead of after — what went in, how much, has it run — and that is the reason. The answers turn a range into a straight figure.
About Longshaw itself
Longshaw is a suburban area in Lancashire, situated on the riverside at an elevation of 147 metres, with terraced housing being the predominant type of accommodation. Longshaw lies approximately 9 miles from Preston and 183 miles from London, making it a commuter-friendly location. Longshaw is surrounded by other nearby places, including Higher Croft, Grimshaw Park, and Nova Scotia, and has a population of around 7344 residents. Longshaw's riverside setting provides a unique character to the area.
Longshaw and Lancashire: where our fuel drain cover runs
Petrol in diesel jobs around Longshaw — part of the BB postcode area — go to vans that also cover the places around it, Higher Croft, Grimshaw Park and Nova Scotia included. The vehicle doesn't need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own drive.
Longshaw: still at the petrol pump?
The best position there is, then — that's where you are. Turned off it remains; then phone.