Addington: Petrol in a Diesel Car? How Worried to Be
Not started? Then less worried than you probably feel. Petrol resting in a diesel tank does nothing to your motor till something pulls it through the system — your ignition priming your pump, your starter, or driving itself. So the honest answer to the first query everyone around Addington asks, "have I wrecked it?", is normally no. To keep the vehicle like that, call Petrol in Diesel and leave the motor alone. The rest of this page explains what petrol really 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.
Your engine and petrol in a diesel: what goes on
On its way through an engine, diesel has two tasks. It lubricates to begin with, and only then does it burn. Very fine tolerances go into the fuel injectors and your high-pressure pump, and only the diesel running through stops their surfaces grinding together.
Petrol handles the first job poorly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on that mixture wearing itself. It's also made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the clattering.
Taken together, they show the shape the trouble takes. Not contact but circulation is what causes the damage. Where the petrol is only inside the tank, it's an issue of fuel, nothing more. A pump that has been running on that petrol is the beginning of a mechanical one, and whatever a worn pump sheds travels on with the fuel to your injectors further on.
How bad is petrol in a diesel? Four scenarios our engineers see around Addington
Fuelled but never started — as good as it gets. At a forecourt, and really only there, the petrol is still limited to that tank — since everywhere else the vehicle was driven to get to it. The job is draining and rinsing on the spot.
Started for a moment, or just your ignition on. Petrol has left the tank and reached the filter and your lines, because your system has been bled. Usually little more than draining, purging and sorting your filter, so still straightforward.
The pump now spent a couple of miles on thinned fuel — that's what driving the car meant. Mileage is only half of it; how hard it was driven matters equally. Either way the work runs to your tank, the lines, the filter and clean fuel through the entire circuit. Driving the kids to Applegarth Academy is one sort of trip. Very different a second time: a run to Westminster, under 15 miles away, or some distance on the M25, under 10 miles from Addington, where the engine never stopped labouring hard.
It protested, and only then stopped: smoke, rattling, a throttle gone soft, an idle gone lumpy. The engine is telling you the fuel is no longer behaving like diesel. Stop on the spot — on the verge on Lodge Lane, at the kerb, down a side road — and don't move it again. Permanent damage is very unusual when a vehicle is pulled over quickly, and the fuel drain and flush that still come first deal with it.
Myths Addington people hear about petrol in a diesel
"Top it up the rest of the way with diesel and it will be fine" — a myth. It will not. Nothing is removed when you top up — the tank just holds more of the same blend. That guidance assumes a diesel fuel system tolerates petrol by percentage. It does not.
Myth: a current diesel copes with a bit of petrol. Rather, the opposite. Finer components and higher pressure are how a current diesel runs its fuel, and that makes the protection matter more, not less.
Myth: "If it starts and drives, there is no harm done." This is the one that fools people. The motorist of a petrol engine fed diesel usually has no choice but to stop, because it will not run, and the damage stops there. Nothing looks to have happened when a diesel fed petrol fires up, ticks over and drives away, as it usually will; meanwhile the pump wears. Running is not the same as fine.
Myth: "Add some two-stroke oil and drive it home." It is an outdated workaround for a separate issue. What petrol has weakened remains weakened, and the petrol stays in your tank regardless.
Myth: "Drain the tank yourself and you're sorted." After the motor has been run, some of that petrol is no longer in the tank: it is in your filter and the lines, and it goes straight back through your pump on the next start. Clearing petrol into a can by the kerbside is also genuinely risky.
How does petrol in a diesel take place?
A careless moment is rarely the cause, and nobody means to do it. One way only, because of the nozzles: the smaller petrol one slips inside a diesel filler with almost no resistance, while the diesel one generally won't fit a petrol vehicle. That's how the forecourt makes it easy.
The moment habit stops matching the vehicle is the moment it happens. Courtesy car, hire car, or a motor that's brand new. One petrol and one diesel on the drive of the same household. A well-known forecourt with the pumps in a different order. A rushed fill en route to West Wickham with a train to catch. Years of petrol vehicles behind you, a diesel Volkswagen Golf in front of you on the forecourt for its first tank — that is when. Add rain, a phone call or a back seat full of kids, and the hand repeats what it has always done.
How to avoid petrol in a diesel on your next fill-up in Addington
- Check the petrol pump, not the colour. In the UK unleaded handles are usually green and diesel black, but not on every forecourt. The label is what counts.
- The first fill in a new car is the time to check your filler flap — inside it, or on the cap, plenty of motors state which fuel to use.
- One of each in the house? Label your key to the diesel — a coloured fob, a sticker — since meaning to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car gets its first tank. It seems daft. It works.
- Tuck the phone away. This is an easy mistake to make while you're thinking about something else.
- Some diesels have a filler built to refuse a petrol nozzle, and devices you can add exist for vehicles without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop checking the pump.
- The moment you realise, stop: less petrol in your tank means a thinner blend. What to do next does not change, though — still don't fire it up.
Put petrol in a diesel in Addington already?
In that case, there's just a short order of things. Starting it is out, and so is switching on the ignition. Still on the forecourt, at Shell or anywhere else? Ask the staff to help you roll the vehicle away from the petrol pump. What was put in, about how much, and whether it has run: tell us those when you call 0333 366 0103.
Corrosion and deposits form the trouble with AdBlue, whereas petrol brings lost protection. So if it was AdBlue, say so — and read its own Addington page.
One petrol in a diesel task around Addington costs more than another. Why?
An honest single quote does not exist here: four scenarios, four separate jobs. What moves your cost is mostly which of them you are in. Two things come after that: the petrol that got in as a share of what that tank holds, then the place the car is in and whether a van can get to it safely.
Three questions come first, before any quote, rather than after — what got in, how much, has it run — and that is the reason. A range turns into a straight figure when the answers are in.
About Addington and its setting
Addington is a suburban area in Greater London, situated approximately 11 miles from central London and 10 miles from Westminster. Addington has a relatively low elevation of 81 metres and is surrounded by other suburban areas such as Forestdale and Spring Park. Addington is characterised by its predominantly terraced housing stock, which reflects the typical residential architecture of the region. Addington remains a small, residential community with a population of around 1370 people.
Fuel drain cover around Addington and across Greater London
Forestdale, Spring Park and Upper Shirley are among the locations around Addington that the same vans work, answering petrol in diesel calls across Addington's CR postcode area. A forecourt, a supermarket car park, a lay-by or your own drive are all spots our technicians work, and your car doesn't need to come to us.
At the petrol pump around Addington, still?
No position is better: that's where you now are. Turned off it remains; then phone.