Woodford: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, if it hasn't been started. Till the ignition primes the pump, the starter cranks, or the car is driven, petrol in a diesel tank just sits there and does no harm. Which makes the truthful reply to that first Woodford question — "have I wrecked it?" — usually no. To leave the vehicle like that, ring Petrol in Diesel then leave your engine switched off. Read on for three things: the effect petrol has inside a diesel motor, the clues of how far it has spread, and the way to make sure you don't repeat it.
What petrol in a diesel does to the engine
Passing through an engine, diesel does two jobs at the same time. Before it burns, it lubricates — and then it ignites. The high-pressure fuel pump and the injectors are designed to extremely fine gaps, and the diesel passing through them is what keeps those surfaces from wearing down against one another.
Badly at the first, not at all at the second: that is petrol. It is thinner than diesel and takes away the lubrication the fuel system hinges on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the rattling comes from.
The shape of the problem is clear when you put those together. Contact doesn't do the harm — circulation does. Petrol in a tank is a fuel fault. After your pump has been labouring on that petrol, a mechanical issue has started: anything shed by a pump that is wearing down is carried downstream to your injectors with your fuel.
Petrol in a diesel around Woodford: how bad is it? Four cases
Fuelled but never started — the best it gets. That petrol is inside your tank and just that tank, and the task is a drain and a flush where the vehicle sits. This is the one situation that can only really take place on a forecourt, as anywhere else your car has been driven to get there.
Started for a second, or just your ignition on. With the system primed, the lines and filter already contain petrol that came from your tank. Usually nothing more than clearing, rinsing and seeing to your filter, so still simple.
Your pump now worked a few miles on thinned fuel — that's what driving the car does. Tank, lines, filter, then fresh fuel run through the entire circuit: that is the work, and the way your car was driven counts as much as the mileage. A school run to Woodford Primary School is one matter. A run as far as Plymouth, under 5 miles away, is a very different job. So is any distance on the M5, under 50 miles from Woodford, where the engine has been running hard throughout.
Driven on till it protested — clattering, smoke, a ragged idle, a soft throttle. The engine is telling you your fuel is no longer acting like diesel. Whether it's the verge on St. Margarets Road, a lay-by or a side road, stop there then leave it. A car pulled over quickly very rarely has permanent damage, since the fuel drain and the flush, which still come first, sort it out.
Petrol in a diesel myths Woodford motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It will not. A fuller tank of the same mix is all you get, since topping up takes out nothing. Percentage is not how a diesel fuel system tolerates petrol, whatever that guidance supposes.
Myth: "A current diesel can cope with a bit of petrol." If anything, the reverse. Protection counts more on newer diesels, not less, since their fuel runs through finer components at higher pressure.
Myth: "If it starts and drives, there's no harm done." This is the one that fools people. Diesel in a petrol motor normally leaves a motor that will not run: the motorist stops, and so does the harm. Feed petrol to a diesel and it normally fires up, ticks over and pulls away as if nothing has happened — all the while its pump wears. Running does not mean fine.
Myth: "Add some two-stroke oil and drive the car home." It is an old fix for a distinct problem. It does not put back what petrol has weakened, and that petrol is still in that tank later.
Myth: "Drain your tank yourself and you're sorted." After the motor has been run, some of the petrol is no longer inside that tank: it's in the fuel filter and your lines, and it goes straight back through your pump at the next start. Emptying petrol into a can at the roadside is also truly dangerous.
Petrol in a diesel: how does it happen?
Carelessness is rarely the cause, and no one means to do it. One way only, since of the nozzles: the slimmer petrol one slips inside a diesel filler with almost no resistance, while the diesel one mostly won't fit a petrol car. That's how the forecourt makes it easy.
When routine and your car stop matching, it occurs. Courtesy car, hire car, or a vehicle that is brand new. Two motors on one driveway, one petrol, one diesel. The pumps in a different order on a familiar forecourt. A train to catch, and a rushed fill on the way to Plymouth. The first fill-up in a diesel Volkswagen Golf after years of driving petrol is precisely the moment it takes place. Add rain, a phone call or a back seat full of children, and your hand does what it has always done.
Woodford drivers: how to avoid petrol in a diesel next time
- The label is what matters, and so check the pump instead of the colour: in the UK unleaded handles are normally green and diesel black, yet not on each forecourt.
- In a vehicle you don't know, look inside the flap over the filler or at the cap before the first fill: many motors print the fuel type there.
- Good intentions count for less than a sticker or a fob in a bright colour on the diesel's key if a home has one of each. So label it.
- It sounds daft 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.
- Thinking about something else is when this becomes an easy mistake to make, and so put the phone away then keep your mind on the pump.
- Some diesels have a filler designed to refuse a petrol nozzle, and devices you can add exist for cars without one. Such an inhibitor helps up to a point — as a safety net, not a reason to stop reading the petrol pump.
- The moment you realise, stop: less petrol inside your tank makes a thinner mix. What to do next does not change, though — still do not fire it up.
Petrol already in a diesel in Woodford? Start here
Then the order of things is brief. Do not turn your ignition on, and don't crank it. Still at the forecourt, at Texaco or anywhere else? Ask the attendants to help you push the car clear of the petrol pump. Then ring 0333 366 0103 and tell us what was put in, about how much, and whether it's run.
If it was AdBlue and not petrol, say so. That's a different fault — corrosion and deposits rather than lost lubrication — and it has its own page for Woodford.
Woodford petrol in a diesel jobs: why one costs more than another
There's no fair single price for this, since the four situations above are four separate tasks. The situation itself does most of the work of moving your cost. Next it is the share — how much petrol went in against how much that tank holds — and after that where your car is and whether a technician can reach it safely.
What got in, how much, and if it has run — three queries we ask before costing, not after, for exactly that reason. A range turns into a straight figure when the answers are in.
About Woodford, for a moment
Woodford is a suburban area in Devon, situated near the coast and approximately 3.6 miles from Plymouth. Woodford sits at an elevation of around 21 metres, with semi-detached housing being the predominant type of accommodation in the area. Woodford is close to nearby places such as Colebrook, Underwood, and Marsh Mills, and is home to a population of around 5300 residents.
Fuel drain cover around Woodford and across Devon
Colebrook, Underwood and Marsh Mills are among the places around Woodford that the same teams work, answering petrol in diesel jobs across Woodford's PL postcode area. Our engineers 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.
Woodford: still at the pump?
Then you are in the best spot there can be. Call, and leave it switched off.