Westwood: Petrol in a Diesel Car? How Worried to Be
Less than you likely are, if it hasn't been started. Petrol sitting in a diesel tank does nothing to the motor until something draws it through your fuel system — the ignition priming the pump, the starter, or driving on its own. So the honest answer to the first query anyone in Westwood asks, "have I wrecked it?", is usually no. Petrol in Diesel is who to phone, with the engine left off, and so it remains that way. Keep reading for three things: the effect petrol has inside a diesel engine, the signs of how far it has got, and ways to make sure you don't repeat it.
What petrol in a diesel does to the motor
Diesel has two jobs on its way through a motor. Lubricating comes before burning; it does both. The high-pressure fuel pump and the injectors are made to extremely fine clearances, and your diesel passing through them is what stops those surfaces from grinding against each other.
Badly at the first, not at all at the second: that is petrol. A pump working on a petrol mix is wearing itself out, because petrol is thinner than diesel and takes away the lubrication your fuel system relies on. Petrol is also designed to resist igniting under compression — the reverse of what a diesel needs from its fuel — and that's where any clattering comes.
The shape of the problem is clear once you put those together. It's circulation that does the harm, not contact. Any tank with petrol in it is a fuel fault. Whatever a worn pump sheds travels on, carried by your fuel, into the fuel injectors further along, which is why a pump that has been working on the petrol is where a mechanical issue begins.
Four situations our engineers see around Westwood: how bad is petrol in a diesel?
Fuelled up, not once started. The best case there can be. Being at a forecourt is what makes this possible: elsewhere, the vehicle has been driven there to begin with. With the petrol kept in your tank alone, it is drained and cleaned right where it stands, and nothing more is needed.
A moment's running, or just the ignition on. Petrol has come out of the tank and reached the filter and the fuel lines, since your system has been bled. Drain, flush, see to the filter: still usually simple.
Driven a couple of miles. Now your pump has spent those miles labouring on thinned fuel. How hard the car was driven matters as much as how far, and this work covers the tank, your lines, the fuel filter and fresh fuel through the entire system. On the school run to the local primary school, the miles is small. Very different again: a run to Glasgow, under 10 miles away, or some mileage on the M74, under 10 miles from Westwood, where your engine kept running hard.
Rattling, a lumpy idle, smoke, a throttle gone soft: driven till it complained. The fuel is not behaving like diesel any more, and your engine is telling you. Whether it's the verge on Wellesley Drive, a lay-by or a side street, stop there and leave it. A vehicle pulled over soon very rarely has lasting damage, since the fuel drain and the flush-through, which still go first, deal with it.
Petrol in a diesel stories Westwood motorists hear
"Top it up the rest of the way with diesel and it will be fine" — a myth. It won't. A fuller tank of the same mix is all it gives, because topping up takes out nothing. 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 reverse. Lubrication counts more on current diesels, not less, because their fuel runs through more precise components at higher pressure.
This is the one that fools people. Myth: "If it starts and drives, there's no damage done." A petrol engine fed diesel usually won't run, and so the driver stops and the damage stops with them. 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 isn't the same as fine.
"A drop of two-stroke oil and drive it home" — a myth, borrowed from a fix from years ago, for a different fault. None of what petrol diluted is put back by it — and later, the tank still contains that petrol.
The next start sends petrol back round the pump out of your lines and your filter, where some of it ends up after the motor has been run. That is why draining your tank yourself doesn't leave you sorted — a myth. It's 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 no one does it on purpose. A diesel nozzle generally won't fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error straightforward, and only in one direction.
When routine and the car stop matching, it takes place. A new vehicle, a hire car or a courtesy car. Two motors on one drive, one petrol, one diesel. A forecourt you know, but with its pumps laid out differently. A train to catch, and a rushed fill on the way to Hairmyres. The first fill-up in a diesel Volkswagen Passat after years of driving petrol is precisely the moment it takes place. The hand does what it has always done when you add rain, a phone call or a back seat full of children.
How to avoid petrol in a diesel on your next fill-up around Westwood
- Read the petrol pump, not the colour. In the UK unleaded handles are normally green and diesel black, yet not on every forecourt. The label is what matters.
- Check the filler flap. Many vehicles 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 household? Label the key to the diesel — a coloured fob, a sticker — because intending to remember is not enough.
- "Diesel", out loud, before you pick up the nozzle — each time a new or hired car needs its first tank. It sounds silly. It does the trick.
- Put your phone away. This is an easy mistake to make whilst you are thinking about something else.
- A misfuel inhibitor helps, up to a point. Some diesels come with a filler designed to reject a petrol nozzle, and add-on devices are available for vehicles without one. They are a backstop, not a reason to stop checking the pump.
- Stop the moment you realise. Less petrol in that tank makes a thinner mixture. It doesn't change what to do next, which is still not to start it.
Put petrol in a diesel around Westwood already?
The order of things is brief, then. Don't turn your ignition on, and do not fire it up. Ask the staff to help you push it clear of the pump if you are still at the forecourt, whether that is BP or anywhere else. Then call 0333 366 0103 and tell us what got in, about how much, and whether it's run.
Corrosion and deposits form the trouble with AdBlue, where petrol brings lost protection. So if it was AdBlue, say so — and read its own Westwood page.
What makes one Westwood petrol in a diesel task cost more than the next
The four situations above are four separate jobs, so no single quote for this would be honest. Which of them you are in is mostly what shifts the cost. The ratio matters next, meaning how much of the tank is petrol, and then the position of your car and whether getting to it is safe for a van.
What was put in, how much, and if it has run — three queries we ask before quoting, not after, for precisely that reason. Those answers change a range into a straight figure.
About Westwood itself
Westwood is a suburban area situated on the riverside in South Lanarkshire, with a mix of detached housing and local amenities. Westwood sits at an elevation of 164 metres, close to the nearby places of Hairmyres, Mossneuk, and Newlandsmuir. Westwood is located approximately 7.5 miles from Glasgow, making it a commuter-friendly location. Westwood has a population of around 5046 residents, who enjoy the area's scenic riverside setting.
Westwood and South Lanarkshire: where our fuel drain cover runs
The teams answering petrol in diesel calls in Westwood, in the G postcode area, also work the spots near it, Hairmyres, Mossneuk and Newlandsmuir included. We drain where the car is — your own drive, a lay-by, a supermarket car park, a forecourt — so it never needs to come to us.
Westwood: still at the pump?
Nothing beats it: that's where you are. Ring, and leave it turned off.