unleaded fuel mixed with diesel

Submitted: Tuesday, Apr 08, 2008 at 21:12
ThreadID: 56448 Views:18586 Replies:13 FollowUps:5
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I seek the collective wisdom of the forum.

This evening, at the most chaotic service station I have visited for a long time (no doubt "fuelled" be the media's hype about the eminent price increases), I inadvertently put 2.4 litres of unleaded petrol in the tank of a common rail 3.0 ltr patrol. I then topped up the tank with 70 ltrs of diesel.

Will this do any damage to the motor ??
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Reply By: Member - 'Lucy' - Tuesday, Apr 08, 2008 at 21:27

Tuesday, Apr 08, 2008 at 21:27
Well it's not a thing of choice normally, however at that dilution rate I would respectfully suggest you will have no trouble at all.

In the colder parts of Australia (ie snow) putting petrol, heating oil in with the diesel is a method used to prevent the diesel from 'waxing up'

From memory the mix is 10% petrol/heating oil and 90% diesel.

Don't think you will have any worries and may get a 'free tank cleaning' along the way.

AnswerID: 297454

Reply By: Hairy (NT) - Tuesday, Apr 08, 2008 at 21:31

Tuesday, Apr 08, 2008 at 21:31
As lucy said...I wouldnt do it by choice,... but I wouldnt drain the tank because it happened.
Be interesting to see what a mechanic says???

AnswerID: 297455

Reply By: donk - Tuesday, Apr 08, 2008 at 21:43

Tuesday, Apr 08, 2008 at 21:43
Iwouldn't stick my hand up & give a opinion on this one but this is copied from the RACQ website Petrol in diesel vehicles

As already mentioned this is the probably the most common situation and depending on the vehicle, potentially the most costly to rectify.

It’s worth looking at the differences between petrol and diesel to understand the effect the wrong fuel will have on an engine. Firstly, diesels are correctly known as Compression Ignition Engines. That means they use the heat generated by compressing the air in the cylinders to ignite the fuel when it is injected. Diesels compress only air in their cylinders as opposed to petrol engines that compress a mixture of both air and fuel and use a sparkplug to ignite the mixture.

The fuels themselves are also quite different. The most common measure of fuel quality for petrol is its octane number, a measure of its ability to resist “knocking” or self-combustion. On the other hand, diesel’s quality is specified by its cetane number, which is a measure of its ignition properties. Simply, one is a measure of how resistant the fuel is to self-ignition and the other is a measure of how well it ignites.

In addition the timing of injection in a diesel engine takes into account the combustion characteristics of the fuel. For instance the time it takes from the point of injection to when the fuel actually begins to burn is important in selecting optimum injection timing. Too early and the piston will still be on its way up and too late will mean that some combustion energy will be wasted. As you can imagine introducing a fuel with the wrong combustion characteristics will have a major impact on performance, and could potentially damage the engine.

Diesel fuel injection equipment relies on the fuel for lubrication. Diesel fuel has lubricating properties but petrol is a solvent that can strip lubricant from moving parts allowing metal-to-metal contact and damage to the very precisely machined (and very expensive) components.

But while an older style diesel engine may tolerate a small amount of petrol (although it definitely isn’t recommended) without too much damage, the newer Common Rail Diesels are unlikely to tolerate any level of petrol without damage. Australia has only recently begun to receive these new engines, but in Europe, where diesel engines are common in passenger cars and where Common Rail diesel engines have been in use for some time, the problems associated with mis-fuelling are well known. In fact it has been reported that vehicle manufacturers are providing their European dealers with detailed instructions about the corrective actions needed in the event of a mis-fuel.

Obviously the extent of the work required to rectify a mis-fuel will depend on the type of vehicle and how long it has operated on the wrong fuel. But in the worst case expect a bill for several thousand dollars as rectification could require repair or replacement of much of the fuel system as well as repairs to the engine itself if it has suffered damage. The best case, where the fuel has been put in the tank but the engine wasn’t started, will involve draining the tank, adding the correct fuel and bleeding the system of air.

AnswerID: 297462

Follow Up By: Member - Roscoe ET (QLD) - Wednesday, Apr 09, 2008 at 08:14

Wednesday, Apr 09, 2008 at 08:14
From discussion I had some time ago with the service manager where I have my vehicle serviced there's a big issue with the effect petrol has on "O" rings and seals within the diesel fuel line and the common rail area.
He advised me that because petrol is a solvent it will SWELL these components which will effect the whole CRD system. From what he said the "O" rings and seals in these systems have been made for diesel and will not tolerate even a small amount of petrol.
He also advised me that contrary to some views he had heard if you mistakenly put petrol in the fuel tank it should be drained no matter how much you put in.
FollowupID: 563506

Reply By: flyboy - Tuesday, Apr 08, 2008 at 22:01

Tuesday, Apr 08, 2008 at 22:01
If the unfortunate happens and your motor suffers damage, keep in mind that some comprehensive insurance policies cover this sort of accidential damage. Keep the fuel receipt for evidence.
AnswerID: 297467

Reply By: pop2jocem - Tuesday, Apr 08, 2008 at 22:07

Tuesday, Apr 08, 2008 at 22:07

At that dilution I doubt that you or your engine would notice the difference IMHO. I was told recently that certain diesel vehicles run reasonably happily on a fuel called JP8. The JP standing for Jet Propulsion and the 8 being the grade commonly used by the US armed forces. This info by the way is commonly available on Wikapedia. Jet fuel as you probably know is basicaly good old fashion kerosene with a few extra nasties thrown in. This enables ops in VERY cold temperatures where diesel turns into jelly. In the past I would have thought that kero would have done immediate and expensive damage to a conventional diesel injection system, however while the ultimate life of these components may be compromosed the vehicles run for quite long periods without obvious harm. There is some loss of power as well.
Keep in mind that these are not common rail systems AFAIK but the old fashioned mechanical pumps and injectiors. I have no idea what effects this practise would have on their more modern cousins and I am in no way advocating that anyone tries this at home but rather to show what these systems are able to digest.

Cheers Pop
AnswerID: 297470

Follow Up By: guzzi - Wednesday, Apr 09, 2008 at 06:39

Wednesday, Apr 09, 2008 at 06:39
JP 8 eqates to our F34 most commonally known as Avtur, the jet fuel used by the ADF.
The primary reason the US armed forces went to JP8 was logistics, It means they only need 1 type of fuel for the tanks, trucks, hummers and attack helicopters.
The fact that it jells somewhere below -53 deg C is an added bonus in cold weather.
F34 runs quite well in older diesels mixed up to 50/50.
FollowupID: 563495

Follow Up By: Member - Glenn D (NSW) - Wednesday, Apr 09, 2008 at 23:05

Wednesday, Apr 09, 2008 at 23:05
Hows it going Stevo

At work we were using avtur in our ground power units for years, just a Cummins Diesel driving a generator.

Only recently gone back to deisel , it must be cheaper.

We also had 2 identical vehicles 1 petrol and 1 deisel, the deisel one didnt like it when filled with a full tank of petrol by accident.

Lubricating properties of Avtur are very different from petrol and that was what the post was about !

FollowupID: 563747

Follow Up By: Member - Glenn D (NSW) - Wednesday, Apr 09, 2008 at 23:07

Wednesday, Apr 09, 2008 at 23:07
Cant spell DIESEL either.
FollowupID: 563748

Reply By: Dave(NSW) - Tuesday, Apr 08, 2008 at 23:40

Tuesday, Apr 08, 2008 at 23:40
With a 3lt Patrol 2.4lts of petrol in a 70lt tank would be your least worry,We used to add petrol to our diesel tanks years ago when I used to do express overnight to give the truck more go or add mothballs (with out the moth lol.) Not good for injectors but!
Cheers Dave....

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AnswerID: 297492

Follow Up By: Richard Kovac - Wednesday, Apr 09, 2008 at 00:33

Wednesday, Apr 09, 2008 at 00:33
Not good for injectors but!
hows that dave?
FollowupID: 563493

Reply By: Member - Warfer (VIC) - Wednesday, Apr 09, 2008 at 00:02

Wednesday, Apr 09, 2008 at 00:02
Crikeys Fella's where only talking 2.4 litres not 24 litres !

Easy done though well done at stopping at that..

AnswerID: 297495

Reply By: Stevo - Wednesday, Apr 09, 2008 at 07:03

Wednesday, Apr 09, 2008 at 07:03
thanks folks
AnswerID: 297507

Reply By: Member - Bucky (VIC) - Wednesday, Apr 09, 2008 at 08:03

Wednesday, Apr 09, 2008 at 08:03
Don't worry about it !

I put 1 lt ULP in my Navara tank every month, just to blow out the cobwebs, works well.

Now I am not too sure about common rail injection, but there will be someone with expertise in this field, out there..

AnswerID: 297517

Reply By: Member - DOZER- Wednesday, Apr 09, 2008 at 11:18

Wednesday, Apr 09, 2008 at 11:18
Do an economy run for us and a seat of the pants opinion on power please....if you knew what was mixed in the diesel you buy around the place, you would never buy it....paint stripper, degreaser, yada-yada....it wont make any difference in that ratio....considering crude oil is refined, and diesal and oil come out, then refined again and kero and oil come out....etc etc you could put 2 drops of 2 stroke oil back in the tank to return the lubrication ratio.
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Reply By: Stevo - Wednesday, Apr 09, 2008 at 11:29

Wednesday, Apr 09, 2008 at 11:29
I spoke to two highly regarded diesel mechanics and one advised "....just keep topping up the tank.." the other advising the same but told me to add "Flashlube" also.
AnswerID: 297548

Reply By: Moose - Wednesday, Apr 09, 2008 at 13:40

Wednesday, Apr 09, 2008 at 13:40
A fella I know once filled his diesel tank with unleaded and drove off. Vehicle soon stopped but suffered no permanent damage. However it was a Toyota and they're tough. I doubt that a Nissan would have survived :-)
AnswerID: 297568

Reply By: Member - John (Vic) - Wednesday, Apr 09, 2008 at 14:03

Wednesday, Apr 09, 2008 at 14:03
I suspect that you have already driven from the servo to home and maybe beyond so its a little late to worry about it now :-)
Just keep topping up with diesel to dilute it over the near term if you are so worried about it.
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