Eyres Monsell: Petrol in a Diesel Car? How Worried to Be
Unstarted? Then less anxious than you likely feel. Until your ignition primes the pump, your starter turns, or your car is driven, petrol in a diesel tank just sits there and does nothing. Which makes the truthful reply to that first Eyres Monsell query — "have I wrecked it?" — normally no. To leave the car like that, call Petrol in Diesel then leave your motor alone. What petrol actually does to a diesel, how to gauge how far it's travelled, and how to keep it from happening a second time: that's the remainder of this page.
Petrol in a diesel: what does it do to the engine?
Passing through an engine, diesel is doing two jobs at the same time. It combusts, and before it ignites it protects. Designed to very fine clearances, the fuel injectors and the pump rely on your diesel flowing through them to stop their surfaces wearing against one another.
Petrol handles the first job badly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on the mixture to wear itself. It is also made to resist igniting under compression — the reverse of what a diesel needs — which is where you hear the clattering.
Together, those leave the shape of the trouble plain. It is circulation that does the damage, not contact. All a tank with petrol in it amounts to is a fuel fault. Whatever a worn pump sheds travels on, carried by the fuel, into your injectors downstream, which is why a pump that has been working on the petrol is where a mechanical fault begins.
Four situations our engineers see around Eyres Monsell: how serious is petrol in a diesel?
The best case there is: filled up, not once started. At a forecourt, and genuinely only there, that petrol is still limited to that tank — since everywhere else the vehicle was driven to reach it. The task is draining and purging on the spot.
Started for a moment, or only your ignition on. Once primed, your system has pulled petrol out of that tank as far as the filter and the lines. That's normally still an easy job — a drain, a flush, and the filter seen to.
A couple of miles driven, and the pump has spent every one of them labouring on weakened fuel. Tank, lines, filter, then fresh fuel put through the entire system: that's this work, and the way the car was driven counts as much as the miles. The school run to Eyres Monsell Primary School is one thing. Very different once more: a trip to Leicester, under 5 miles away, or any distance on the M1, under 3 miles from Eyres Monsell, where the engine never stopped labouring hard.
Driven till it protested. Clattering, an uneven idle, smoke, a throttle that has gone soft. The fuel isn't acting like diesel any more, and the motor is telling you. Stop where you are — on the verge on Sturdee Close, at the kerb, down a side road — and don't move it again. A car stopped early very rarely has lasting damage, as the drain and the flush-through, which still come first, deal with it.
What Eyres Monsell people get told about petrol in a diesel — and the myths in it
Myth: "Fill it the rest of the way with diesel and it will be fine." It will not. Nothing is removed when you top up — that tank simply carries more of the same blend. That advice supposes a diesel fuel system handles petrol by percentage. It does not.
Myth: a current diesel copes with a bit of petrol. Rather, the reverse. A newer diesel runs its fuel through more precise parts at higher pressure, which makes the lubrication matter more, not less.
This is the one that catches people. Myth: "If it starts and drives, there's no damage done." Feed diesel to a petrol motor and it usually won't run, so the driver stops — and the damage stops with them. Feed petrol to a diesel and it generally starts, idles and drives away as if nothing happened — all the while its pump wears. Running isn't the same as fine.
An old fix for a different problem is behind this one. Myth: "Add some two-stroke oil and drive the vehicle home." What petrol has diluted remains thinned, and the petrol stays in your tank anyway.
If the motor has run, part of that petrol is in the filter and your lines, not the tank — and the next start sends it straight back through the pump. So the myth "drain that tank yourself and you're sorted" does not hold. It is also genuinely risky to drain petrol into a can at the roadside.
Petrol in a diesel: how does it take place?
It's rarely carelessness, and nobody does it on purpose. The forecourt makes it simple: the petrol nozzle is the narrower of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly won't go into a petrol motor at all. So the mistake runs one way.
When habit and your car stop matching, it takes place. A vehicle that is new to you — a hire car, on loan as a courtesy car, or brand new. A household with one petrol and one diesel on the drive. Your usual forecourt, its pumps now in a different order. Filling up in a hurry en route to South Wigston, with a train to catch. The first fill-up in a diesel Renault Megane after years of driving petrol is precisely the moment it happens. Add a back seat full of kids, a phone call or rain, and the hand wins.
Next time you fill up in Eyres Monsell: avoiding petrol in a diesel
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Read the pump's label; the colour is only a clue.
- Many motors state the fuel inside your filler flap or on the cap, so check there on your first fill in a car you do not know.
- Good intentions do less than a sticker or a fob in a vivid colour on the diesel's key when a household has one of each. So mark it.
- It seems silly and it does the trick: on the first fill in a new or hired car, say "diesel" aloud before you take the nozzle off the pump.
- Whilst you are thinking about something else, this is an easy mistake to make — so tuck your phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to refuse a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop reading the pump.
- Less petrol means a weaker mixture, and so stop the moment you realise — though remembering that your next step is unchanged. It is still not to start the car.
Already put petrol in a diesel in Eyres Monsell?
Then, there's only a short order of things. Never fire it up, and do not switch your ignition on. Ask the staff to help you roll it away from the pump if you are still on the forecourt, whether that's Shell or anywhere else. Call 0333 366 0103 next, with three answers — the fuel, the approximate quantity, and whether it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different problem — Eyres Monsell has a page all for it.
Eyres Monsell petrol in a diesel tasks: why one costs more than another
There is no fair single price for this, because the four scenarios above are four separate tasks. What shifts the cost is mostly which of them you are in. Where your car is counts too, and whether our van can safely get to it, after the share of petrol to what the tank takes.
Three questions come first, before quoting, rather than after — what went in, how much, has it run — and that is the reason. Those answers change a range into a straight figure.
About Eyres Monsell
Eyres Monsell is a suburban area located on the outskirts of Leicester, approximately 3 miles south of the city centre. Eyres Monsell sits at an elevation of around 89 metres, in the gently rolling landscape of the East Midlands. Eyres Monsell is characterized by its predominantly semi-detached housing stock, with nearby places including Glen Parva, Aylestone, and Aylestone Park. Eyres Monsell is home to a population of around 9063 people, making it a sizable residential community within the Leicester urban area.
Fuel drain cover in Eyres Monsell and across Leicestershire
Petrol in diesel call-outs around Eyres Monsell — part of the LE postcode area — go to teams that likewise cover the spots around it, Glen Parva, Aylestone and Aylestone Park among them. You need not bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all locations where we work.
Eyres Monsell: still at the pump?
The best position there is, then — that's where you are. Switched off it stays; then ring.