How Worried Should You Be? Petrol in a Diesel Car in Rowhill
Far less than you probably are, if it has not been started. Until the ignition primes your pump, the starter turns, or your vehicle is driven, petrol in a diesel tank simply sits there and does nothing. Which means the truthful reply to the first Rowhill query — "have I wrecked it?" — usually no. Leave the engine off then phone Petrol in Diesel — that keeps it like that. What petrol really does to a diesel, how to gauge how far it's gone, and how to stop it from happening again: that's the remainder of this page.
Petrol in a diesel: what does it do to your engine?
Two tasks fall to diesel on its journey through a motor. It burns, and before it ignites it lubricates. Your high-pressure pump and your injectors are built to very fine gaps, and your diesel passing through them is what stops those surfaces from wearing against one another.
Of those two jobs, petrol manages the first poorly and the second never. A pump working on a petrol mixture is wearing itself out, since petrol is runnier than diesel and takes away the lubrication the fuel system relies on. Petrol is also made to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that is where any rattling starts.
The shape of the problem is clear when you put those together. Contact does not do the harm — movement does. Any tank with petrol in it is a fuel issue. Once the pump has been labouring on that petrol, a mechanical issue has started: anything shed by a pump that is wearing travels onward to the fuel injectors with the fuel.
How serious is petrol in a diesel? Four scenarios our technicians see in Rowhill
Fuelled, and not started: nothing beats it. Just the tank has petrol in it, and so the task is draining the tank and flushing your system where the car sits. This situation can only truly happen on a forecourt: anywhere else, the car got there by being driven.
Your ignition switched on, or a brief start. Once primed, your system has pulled petrol from your tank as far as the fuel filter and the fuel lines. That is generally still a straightforward task — a drain, a flush, and the fuel filter seen to.
Your pump now worked a few miles on thinned fuel — that's what driving the vehicle meant. How hard the car was driven matters as much as how far, and this work takes in that tank, the fuel lines, the filter and clean fuel through the whole system. Short trips, such as the school run to Ottershaw Christ Church Church of England Infant School, are one thing. Getting as far as Westminster, under 25 miles away, makes a very different job — as does any distance on the M25, under a mile from Rowhill, with your engine running hard all the way.
Driven till it complained. Knocking, a lumpy idle, smoke, a throttle that has gone soft. The motor is telling you the fuel is no longer acting like diesel. Pull up where you are — on the verge on Howards Lane, at the kerb, down a side road — and don't move it. A car stopped quickly very rarely has long-term damage, since the fuel drain and the flush-through, which still come first, sort it out.
Myths Rowhill people hear about petrol in a diesel
False: topping up to full with diesel makes it fine. It does not. A bigger tank of the same mix is all it gives, because topping up removes nothing. The idea behind the guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
If anything, the reverse is true. Myth: "A modern diesel can cope with a bit of petrol." At higher pressure, through finer components: that is how a modern diesel handles its fuel, and so the protection matters for more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools drivers. Diesel in a petrol motor usually means a motor that will not run: the driver stops, and so does the harm. While the pump wears, a diesel fed petrol normally starts, ticks over and drives away as if nothing has happened. A running engine doesn't mean fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old fix for a separate problem. None of what petrol diluted is put back by it — and later, that tank still holds the petrol.
Myth: "Drain that tank yourself and you are sorted." Once the engine has run, some of the petrol is no longer inside the tank: it's in the fuel filter and the lines, and it goes right back through your pump at your next start. Also, a can of petrol drained by the roadside is truly dangerous.
How petrol ends up: petrol in a diesel
It's seldom carelessness, and no one does it on purpose. One way only, since of the nozzles: the smaller petrol one slides inside a diesel filler with almost no resistance, whereas the diesel one mostly will not fit a petrol vehicle. That's how the forecourt makes it straightforward.
Habit and your car getting out of step is when it occurs. Hire cars, courtesy cars, and cars that are new to you. Two vehicles on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A hurried fill en route to Addlestone with a train to catch. Exactly the moment it occurs: after years of driving petrol, someone fills a diesel Renault Clio for the first time. With rain, a call arriving, or a car full of children to deal with, the hand simply does what it always has.
How to prevent petrol in a diesel at your next fill-up around Rowhill
- Not every forecourt in the UK keeps to green for unleaded and black for diesel, even if most generally do. Check the pump's label; the colour is only a hint.
- Inspect your filler flap. Plenty of motors state the fuel type inside the flap or on the cap. Look at it on your first fill in any motor you do not know.
- One of each in the home? Label your key to your diesel — a coloured fob, a sticker — since intending to remember isn't enough.
- It sounds silly and it does the trick: on your first fill in a new or hired car, say "diesel" out loud before you lift the nozzle off the petrol pump.
- Whilst you are thinking about something else, this is an easy mistake to make — so put the phone away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to block a petrol nozzle, and add-on devices exist for vehicles without one. They are a safety net, not a reason to stop checking the petrol pump.
- Less petrol makes a thinner blend, and so stop as soon as you realise — while remembering that your next step is unchanged. It is still not to crank it.
Rowhill: already put petrol in a diesel?
Then, there's only a short order of things. Do not switch the ignition on, and do not fire it up. If you are still at the forecourt — Shell or anywhere else — ask the staff to help you roll the vehicle clear of the petrol pump. Ring 0333 366 0103 next, with three answers — the fuel, the rough volume, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost protection, make it a different issue — Rowhill has a page all for it.
Rowhill petrol in a diesel jobs: why one costs more than another
Four different jobs lie behind the four situations above — which is why there is no honest single quote. What shifts the cost is chiefly which of them you're in. Where your car is counts too, and whether a technician can safely get to it, after the share of petrol to what the tank takes.
That is why our engineers ask three questions before quoting instead of after: what got in, how much, and whether it has run. Given those replies, there is a straight figure rather than a range.
About Rowhill and where it is
Rowhill is a locality in Surrey, situated on the riverside at an elevation of 38 metres, with detached housing being the predominant type of accommodation. Rowhill lies near several other settlements, including Row Town, Ottershaw, and New Haw, and is approximately 19.5 miles from London. Rowhill has a population of around 1555 residents, who enjoy the area's scenic riverside setting. Rowhill is also close to the nearby city of Westminster, which is about 19.3 miles away.
Rowhill and Surrey: where our fuel drain cover runs
Petrol in diesel call-outs in Rowhill — part of the KT postcode area — go to vans that also cover the spots round it, Row Town, Ottershaw and New Haw included. We drain where the vehicle is — your own driveway, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
In Rowhill and still at the pump?
The best spot there is, then — that is where you are. Keep it off. Phone.