Petrol in Diesel

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Thu 28 Apr 2022 20:15
Petrol in Diesel - Dingle232

Before anyone asks this was not me! :-)

A relative of mine (elderly) accidentally put around 0.95L (from the receipt) of unleaded in his disel vehicle earlier today. He filled the rest up with diesel and drove home without any issues. I got the call as he started to worry when he got home and is wondering whether to have his fuel system drained.

With my limited knowledge, IF, there's any damage done it's probably done given that the wrong fuel will have been pumped around the engine but can any suitably qualified folks give a definitive (and pragmatic) answer as to whether he needs to go with the fuel drain or whether it's such a small amount that there's nothing to fret about?

Reading places like the RAC website seems to suggest that up to 5% of petrol in a diesel should do any lasting harm. This is nowhere near that but I'd like to give him some good advice.

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Thu 28 Apr 2022 20:23
Petrol in Diesel - Brit_in_Germany

At that dilution, my view is that it is unlikely to be a problem but to be on the safer side, he could add a double dose of Millers Diesel Power Ecomax (from e.g. Halfords).

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Thu 28 Apr 2022 20:27
Petrol in Diesel - John F

No worries.

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Thu 28 Apr 2022 20:30
Petrol in Diesel - catsdad

Even companies with a vested interest in scaring us re misfuelling say 5% is OK. I wonder in the event of a serious 100% misfuel how much they can pump out anyway?

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Thu 28 Apr 2022 22:45
Petrol in Diesel - bathtub tom

How much diesel was mixed with the petrol? Include what was already in the tank and how much was added. What was the age and model of the car?

Edited by bathtub tom on 28/04/2022 at 22:46

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Thu 28 Apr 2022 23:06
Petrol in Diesel - Dingle232

I'm not entirely sure but he tends to fill up each Friday and doesn't do much driving. I'd suspect from what he told me the tank would have been 3/4 full, then the small amount of petrol (less than a litre) added followed by him filling to the brim with diesel.

His car is a Kia Ceed and (I think) around 18 months old, maybe a tad older.

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Thu 28 Apr 2022 23:11
Petrol in Diesel - Andrew-T

I'd suspect from what he told me the tank would have been 3/4 full, then the small amount of petrol (less than a litre) added followed by him filling to the brim with diesel.

If the tank was 3/4 full of diesel to start with, I suggest there is absolutely no reason to lose any sleep at all.

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Fri 29 Apr 2022 03:41
Petrol in Diesel - daveyK_UK
I know someone who accidentally put £20 worth of petrol in a diesel Ford Focus hire car; after realising their error they filled up the rest of the tank with diesel and topped it up again with diesel when it had used a quarter of a tank.
No issues
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Fri 29 Apr 2022 03:44
Petrol in Diesel - edlithgow

At that dilution, my view is that it is unlikely to be a problem but to be on the safer side, he could add a double dose of Millers Diesel Power Ecomax (from e.g. Halfords).

I dunno what is in Millers Diesel Power Ecomax, so if I was in that situation (as I have been, though I put a couple of gallons of petrol in, it was a hire car, and there were no apparent effects, at least in the short term) with my own car, I'd chuck a litre of low ash 2-stroke oil in it, though its probably unnecessary to do anything.

From the web page Millers Diesel Power Ecomax seems to be mostly a fuel system cleaner, which is not really what is wanted here. What's wanted is (mostly) fuel pump lubrication

"Lubricity" is mentioned as one of the benefits, but its what 2-stroke oil does as a full-time job.

I suppose there might be some additional sooting-up of a dpf-equipped vehicle, if this was one.

Edited by edlithgow on 29/04/2022 at 05:35

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Fri 29 Apr 2022 12:11
Petrol in Diesel - Gibbo_Wirral

I know a few Pug 407 owners who regularly use 2 stoke in a tank full , it doesn't affect their DPFs.

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Fri 29 Apr 2022 17:36
Petrol in Diesel - thunderbird

I know a few Pug 407 owners who regularly use 2 stoke in a tank full , it doesn't affect their DPFs.

The Pug 407 is a very old car now, the newest is 11 years old. The older DPF's on those (EURO 3 and EURO 4 ?) are probably not as sensitive to oils as DPF's on newer EURO 5 and EURO 6 cars.

Its also probable that on older cars like these the DPF's have been illegally deleted or drilled out. No amount of 2 stroke would cause an issue on those.

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Fri 29 Apr 2022 20:55
Petrol in Diesel - Xileno

I cannot believe that the amount of petrol mentioned by the OP would be a problem.

Years ago about 1992 I had a holiday job working for a frozen food company and spent most of my day behind the wheel of 205 and Fiesta diesel vans (basically the three door versions with blanked out windows) and in the boot was some 2 stroke oil. The fleet manager said to use that if I ever mis-fuelled. I thought he was pulling my leg to start with but was perfectly serious about it. I made sure I never needed it. This was long before the days of DPF.

The 205 was a dream compared to the Fiesta. The latter made enough noise to wake the dead. I was always disappointed if I turned up to the yard and there was only a Fiesta to have for the day.

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Fri 29 Apr 2022 22:40
Petrol in Diesel - bathtub tom

About fifteen years ago I had a delivery job. Three new Peugeot, diesel vans turned up and they were gutless. I had a look at one and found it wasn't getting full fuelling at full throttle. A sort of hairclip, that restricted throttle opening. I sorted that and promptly had the other driver's who had used the one I 'adjusted' asking me to sort out the others.

Christ knows what the PDI involved, but they were dangerous when trying to pull out of a junction.

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Fri 29 Apr 2022 23:04
Petrol in Diesel - Andrew-T

I had a look at one and found it wasn't getting full fuelling at full throttle. A sort of hairclip, that restricted throttle opening. I sorted that ....

I remember doing something similar to take the slack out of the throttle cable on a 306 diesel, I think it was.

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Sat 30 Apr 2022 20:58
Petrol in Diesel - Xileno

I remember a thread on here years ago (I searched but couldn't find it as the search tool is a bit bizarre at times) where it said a trick with the 205 to extract a bit more power was to bend the accelerator pedal a bit!

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Mon 2 May 2022 11:21
Petrol in Diesel - Moodyman
I put 7l into a Lexus IS before I noticed. I then added c. 30+l of diesel to full.

It drove ok, but occasionally misfired. As the fuel level
decreased, I kept topping up diesel to dilute the petrol. After 3-4 occasions of 5-10 litre top ups, car was back to normal.

Edited by Moodyman on 02/05/2022 at 11:22

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Tue 3 May 2022 11:28
Petrol in Diesel - Zippy123
If your friend wants to be over cautious, use a little diesel and fill up, repeat. Each fill will will dilute the petrol a little.

Anecdotally and without realising l, I put a couple of gallons of petrol in my nearly empty Vauxhall Mokka. Only a couple of gallons as it was at a motorway service station (£££) and I was about 40 miles from home.

Later that day it refused to start. AA called and diagnosed petrol in the tank and the receipt confirmed it.

They got a specialist to drain the tank and it restarted fine. It had about 30k on the clock and I changed it when it had over 80m on the clock with no further issues. It’s still being used and is on the MOT checker site with over 120k on the clock.
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Tue 10 May 2022 20:41
Petrol in Diesel - hawkwind

I've just put 5 litres of unleaded vpower into my 2013 1.6 golf TDI and realised my mistake so I filled up with vpower diesel thinking it should dilute it and be ok, but after reading around it seems like that is not the case with modern engines.

I drove it 7 miles home, have I likely done some damage and should I not drive it now until I get the tank drained?

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Tue 10 May 2022 21:08
Petrol in Diesel - Xileno

On the assumption the tank holds 60 litres then you have about 8% petrol. If the car was mine I wouldn't bother doing a drain. I might follow some of the advice above re. additive or topping up with diesel when space in the tank allows.

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Tue 10 May 2022 21:38
Petrol in Diesel - hawkwind

Thanks, hopefully it is going to be ok.

Really annoyed as I had just head the EGR done a few hours earlier as well and I really cannot afford anymore expense right now.

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Wed 11 May 2022 19:41
Petrol in Diesel - hawkwind

Well I added Dipethane additive then took it out for a 100 mile run taking it steady through the gears and keeping the speed down

It drove nice and smooth, no sign of any smoke, lumpiness or misfiring.

When I got back I topped up again with vpower.

Hoping for the best but I guess only time will tell.

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