How Worried Should You Be? Petrol in a Diesel Car in Craigens
Not started? Then less worried than you probably are. "Have I ruined it?" is the first question anyone in Craigens asks, and the truthful answer is normally no, because petrol left in a diesel tank harms nothing until it is drawn through your fuel system — by ignition priming, by your starter, or by being driven. Leave your motor off and call Petrol in Diesel — that is how you keep it like that. The remainder of this page covers what petrol actually does to a diesel, how to tell how far it has got, and how to make sure it doesn't happen to you a second time.
Petrol in a diesel: what does it do to the engine?
Passing through an engine, diesel is doing two things at once. It combusts, and before it combusts it lubricates. Made to very fine gaps, your injectors and your pump rely on the diesel moving through them to stop their surfaces wearing against one another.
Poorly at the first, not at all at the second: that's petrol. The knocking comes from petrol being designed not to ignite when compressed, which is precisely the reverse of what a diesel needs. On top of that it is runnier than diesel, it strips away the protection the system depends on, and any pump running on such a blend is wearing itself.
The shape of the problem is clear when you put those together. The damage is done by circulation, not by contact. Petrol in a tank is a fuel fault. The start of a mechanical problem is a pump that has been working on that petrol — and whatever a worn pump sheds travels on with the fuel to the injectors downstream.
How bad is petrol in a diesel? Four situations we see in Craigens
Fuelled up, never started. The best case there is. Being on a forecourt is what makes this the case: elsewhere, the vehicle has been driven there to begin with. With that petrol held inside your tank alone, it is drained and cleaned on the spot, and nothing more is needed.
A brief spell of running, or just the ignition on. The system has been bled, and so petrol has left your tank and reached the filter and the lines. Still usually straightforward: drain, flush, and the filter dealt with.
Driven a couple of miles. Now your pump has spent those miles labouring on weakened fuel. How hard your car was driven matters as much as how far, and this work covers your tank, the lines, your filter and clean fuel through the entire circuit. Short trips, such as the school run to the local primary school, are one matter. Getting as far as Glasgow, under 50 miles away, makes a very different job — as does any mileage on the M77, under 25 miles from Craigens, with the motor labouring hard the whole time.
Driven on until it complained — rattling, smoke, a ragged idle, a dead throttle. The motor is telling you the fuel is no longer behaving like diesel. Stop wherever you are — the verge on Cairnscadden Road, a lay-by, a side street — and leave the car where it is. A vehicle stopped early very seldom has long-term damage, because the fuel drain and the flush-through, which still go first, sort it out.
Craigens drivers and that 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 by topping up — you are left with a bigger tank, still the same mix. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance supposes.
Myth: a newer diesel copes with a bit of petrol. If anything, 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.
Myth: "If it starts and drives, there is no damage done." This is the one that fools motorists. Feed diesel to a petrol engine and it usually will not run, and so the driver stops — and the harm stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Fine and running aren't the same at all.
Not so: a two-stroke additive makes it safe to drive home. It was an old fix, supposed for another problem. That petrol is still in that tank after that, and whatever it has diluted is not put back.
Myth: "Drain the tank yourself and you are sorted." After your engine has run, some of the petrol is no longer in your tank: it's in your filter and the fuel lines, and it goes straight back through your pump on the next start. Clearing petrol into a can by the kerbside is also really hazardous.
How does petrol in a diesel happen?
It is rarely carelessness, and nobody does it on purpose. A diesel nozzle mostly won't fit a petrol motor, but the smaller petrol nozzle goes into the filler of a diesel nearly without resistance — so forecourts make this one mistake simple, and just in that direction.
The moment habit stops matching the car is the moment it happens. A new motor, a hire car or a courtesy car. One petrol and one diesel on the driveway of the same household. The pumps in a different order on a familiar forecourt. Rushing for a train outside Auchinleck and fuelling up en route. A new-to-you diesel Renault Clio, its first fuelling, and a motorist used to petrol: precisely when it occurs. Throw in a back seat full of children, a phone call or rain, and habit takes over.
How to prevent petrol in a diesel on your next fill-up around Craigens
- Not every forecourt in the UK follows green for unleaded and black for diesel, though most generally do. Check the petrol pump's label; the colour is only a hint.
- Many motors state the fuel type inside the filler flap or on the cap, and so check it on your first fill in any motor you don't know.
- Good intentions count for less than a sticker or a fob in a vivid colour on your diesel's key when a household has one of each. So label it.
- 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 seems daft and it works.
- Mistakes like this are easy to make while your mind is on something else, so your phone goes away.
- Up to a point, a misfuel inhibitor helps: some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for the remainder. Treat it as a backstop, then keep checking the petrol pump.
- Stop the moment you notice. Less petrol in your tank makes a weaker blend. It doesn't change what to do next, which is still not to fire it up.
Put petrol in a diesel in Craigens already?
Then, there's only a short order of things. Leave it unstarted, with the ignition switched off as well. If you are still at the forecourt — the nearest petrol station or anywhere else — ask the attendants to help you roll the car clear of the pump. Ring 0333 366 0103 next, with three facts — your fuel, the approximate volume, and whether it has run.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and see its own Craigens page.
One petrol in a diesel job around Craigens costs more than another. Why?
There is no honest single price for this, because the four scenarios above are four separate jobs. Chiefly, your cost shifts with which situation you're in. The ratio counts next, meaning how much of that tank is petrol, followed by the location of your car and whether reaching it is safe for our van.
Before any quote, not after, come three questions: the fuel that got in, the volume, and if it's run. That's why. The replies turn a range into a straight figure.
About Craigens itself
Craigens is a small village in East Ayrshire, situated inland at an elevation of 168 metres, with terraced housing being the predominant type of accommodation. Craigens lies approximately 29 miles from Glasgow and is surrounded by nearby places such as Netherthird, Barshare, and Logan. Craigens has a population of around 568 people and is located in a rural area, relatively far from London at a distance of 320 miles. Craigens is part of the wider East Ayrshire landscape, characterised by rolling hills and countryside.
Craigens and East Ayrshire: where our fuel drain cover reaches
Petrol in diesel calls around Craigens — part of the KA postcode area — go to teams that also cover the locations round it, Netherthird, Barshare and Logan included. No need to bring the car to us. Forecourts, supermarket car parks, lay-bys and your own drive are all spots where we work.
At the petrol pump in Craigens, still?
Then you are in the best place there is. Turned off it remains; then call.