Old Petrol Debunking the Theory

[Bigplumbs]

At this time of year it is common for people to start to worry about what is Offton described as 'old Petrol' and what to do about it. They fear that is they leave it in their tanks they might have big problems next year.

Well we have an old Vauxhall Vectra that has been laid up for 4 plus years and the men are coming today to take her to the Scrapyard. In their email to me where they offered to take her away (paying us a decent price I thought) they asked if she would start. Having not even tried to start the old girl for 4 years I doubted it. Rather than just answer no I thought I would give here a go. I lifter the bonnet and saw that the battery indicator was green and that I had disconnected it all those years ago. I reconnected it and with her indoors inside the car she turned it over and hey presto it fired up and sat their ticking over and purring like a kitten. The breaks however were seized on so no moving her easily.

Now this is of course a car engine and not a boat engine. However the tank was about 1/4 full so plenty or air in that tank. The petrol was probably E5 and had been sitting well over 4 years. I laid the car up because the gearbox developed an issue.

We also have a Toyota Previa that was laid up for at least 7 years and during lockdown we converted that into a micro camper van. That also started on the even older petrol in its tanks with no issues.

So to be honest I wonder about all the worries people have about so called old petrol in tanks based on these and other real world examples.

Should you believe in the old petrol theory I wonder how on earth a person would easily and legally dispose of what could easily be many ltrs of petrol.

Here is a pic of the old girl

 

[julians]

It varies from engine to engine , and exactly how old the petrol is , some engines can tolerate very old petrol (like your vectra ), some cant. We have a suzuki df6 outboard that wont run on old* fuel at all, the carb jets get gummed up , but the same tank of old petrol works fine in fiat panda with whatever engine they use -I know because that is where we 'dispose' of it.

The mercury 300hp outboard we have seems fine on 12 month old fuel - I havent used anything older than that in it.

*I cant quantify how old is too old for the suzuki, I just know that at about 9 months old it gums the carb jets up.

So I dont think you have debunked anything, except that the engine in your vectra seems to start fine with old fuel

 

[Bouba]

It’s those little engines we use on dinghies…two or three horsepower with those tiny tiny jets in their little carburettor that are most susceptible…so at least drain the carb even if you leave fuel in the tank

 

[wallacebob]

Fuel injected engines don’t have the same issues. Small engine carbs are the problem. Suzy Df engines: tuned for tight emissions, so very particular with fuel in my experience too.
I only use E5 plus stabiliser now.

 

[dunedin]

Fuel injected engines don’t have the same issues. Small engine carbs are the problem. Suzy Df engines: tuned for tight emissions, so very particular with fuel in my experience too.
I only use E5 plus stabiliser now.

Also by definition things with very old petrol in them do not disprove the worry about modern petrol with higher biofuel content having issues. E10 was mandated in the Uk only from September 2021 so would not be in these old scrap cars.

 

[Bigplumbs]

It’s those little engines we use on dinghies…two or three horsepower with those tiny tiny jets in their little carburettor that are most susceptible…so at least drain the carb even if you leave fuel in the tank

Yup I tried running my carb dry and then my problems started that I never had before. This was on 2 no 2 stroke outboards. In running dry you can never get it all out of the carb chamber but it is way less and the fuel evaporates and you get small bits of dried out 2 stroke oil that blocked the jets. See pic below.

I am going to do as I have also done and just leave the engine as it was when it was last used with its bowl full up.

This was quicksilver Premium 2 stroke oil. The first pic is what I poured out of the carb. The second is after I let it evaporate. The blue specs are semi hard dried oil which blocked the idle jet

 

[Bigplumbs]

Here is a little video of the Vectra starting and running on the very old petrol and indeed being taken to the great scrap yard in the sky.

Some people on another forum also claimed that we did not start this car on the old battery that was left in the car disconnected for over 4 years. Well we did and it amazed me also

 

[vas]

fwiw, not much!

2011-2015 around 400lt of diesel in MiToS sitting there while rebuilding the whole boat. Fired up first time after the four years, used the diesel fine.
2014-2019 Fiat coupe Lancia HF Turbo 2.0lt engine, tank half full sat in the garage (still there) charged battery, fired up in 4-5 turns of the crank.
Mind all that in sunny Greece with mild(ish) winters and lowish humidity

EDIT: re 2strokes, my yamaha 2cyl 70hp engine on my avon jetrib works fine with fuel left in the carbs for ever, because it sprays the oil in the carb throat and doesn't mix it before the jets. So only fuel in the carb, nothing to mess and block jets. OTOH, it's a bit dangerous as if for some reason one of the spraying nozzles for oil blocks (or the oil pump fails) you ruin the engine...

 

[paradave]

My Stihl chainsaw hates old fuel and by old I mean older than 3 months, it simply won’t run on it. Debunked

 

[Fire99]

I can only go from experience but a previous motorbike with 4 carburettors was not a happy bunny when a part full fuel tank was left for 6 months over winter. My 10hp 2-stroke outboard has had carb gumming issues BUT the environment it lives in is very harsh when you think about it. Little fuel tanks (metal or plastic) with fairly cheap seals, lids, breathers and nothing like as dare I say 'developed' as a car fuel system. And then some of us get petrol from marina supplies which also seem to be anything between brilliant and terrible, there are a lot of factors in the boaty environment. I'm more concerned about E10 than I am fuel age. That seems like introducing a factor that is almost asking for issues..

 

[Binnacle]

Did that OPs car have a standard lead acid battery in it, or something very very special in the chemistry ?

It's one of the (hitherto ?) immutable laws of physics that self-discharge rates for LA are around 4% per month, and frankly I am astounded that after 4 years, there was enough power to do anything even light up the ignition circuit. Did the OP have even a tiny solar panel in the circuit, or connect up a dirty great big lorry battery before starting ?

Battery Performance Characteristics - How to specify and test a battery

 

[Bigplumbs]

Did that OPs car have a standard lead acid battery in it, or something very very special in the chemistry ?

It's one of the (hitherto ?) immutable laws of physics that self-discharge rates for LA are around 4% per month, and frankly I am astounded that after 4 years, there was enough power to do anything even light up the ignition circuit. Did the OP have even a tiny solar panel in the circuit, or connect up a dirty great big lorry battery before starting ?

Battery Performance Characteristics - How to specify and test a battery

Well in the video you can see exactly what the battery was (about 52 seconds in) but for your information is was an inexpensive (cost about £55) smallish lead acid battery. And as I said despite what all the theory mongers in the world will tell you. I disconnected it over 4 years ago and never did a thing to the car in that time. I reconnected it yesterday and to my amazement. it quite easily started the car that had not been started in over 4 years. This is real world and it certainly surprised me.

 

[Seastoke]

I realise now why they call you big plumbs, because you have 2acres full of boats and cars.

 

[Bigplumbs]

I realise now why they call you big plumbs, because you have 2acres full of boats and cars.

Not quite it was because of Victoria plumbs and lead in the nose of RC Planes note the B

 

[Momac]

 

[Bigplumbs]

View attachment 165683

View attachment 165684

Yes it is very easy to copy and past theory from the Internet........ The whole point is that this is not bourn out in real life as my video shows.

You have got to wonder why people believe this copy and pasted stuff when real life shows otherwise.

What are you going to do with all your 'old Petrol'

 

[Momac]

Yes it is very easy to copy and past theory from the Internet........ The whole point is that this is not bourn out in real life as my video shows.

You have got to wonder why people believe this copy and pasted stuff when real life shows otherwise.

What are you going to do with all your 'old Petrol'

I use up fuel not used in my outboard in my lawnmower. Just used using the last of last years petrol now.
The lawnmower runs better on fresh fuel which demonstrates in real life the copy and paste items are correct. The same is true of my little and very old outboard.
Relatively modern petrol engines are tolerant of fuel quality. You didn't drive the Vectra so you don't know whether it went okay or not.

 

[Bigplumbs]

I use up fuel not used in my outboard in my lawnmower. Just used using the last of last years petrol now.
The lawnmower runs better on fresh fuel which demonstrates in real life the copy and paste items are correct. The same is true of my little and very old outboard.
Relatively modern petrol engines are tolerant of fuel quality. You didn't drive the Vectra so you don't know whether it went okay or not.

Well I also have a 1998 Toyota Previa which was also laid up for about 5 years and we drive that all the time. We converted it into a micro camper. It also started first time on the petrol that had been in the tank over 5 years so that puts that one to bed. The Vectra was running just fine as can be seen in the video. Driving it would have made no difference.

In my many boat engines from 10 - 200 hp the fuel is left in the tanks for absolutely ages and they all start and work.

How about you try a real test and leave some petrol for 2 - 3 years and see what happens.

Very strange how you wont believe real life examples.

 

[prestomg27]

I bought a classic wooden healey skimaster with a redband mercury 35hp in 1986. The boat had been in my dad's friend's garage since maybe 1972 possibly earlier.

When i got it home there was fuel in the tank. I primed the bulb and thoughy i would give it a little pull and it started and ran straight away. I did then drain and service everytging but i was shocked that 15-20 year old petrol still worked.

 

[Portofino]

Small carbs with large float bowls AND tiny channels and jets gum up if left for long periods .The bowl needs to hold sufficient quantity so when it eventually evaporates off the gum semi or totally blocks jets .Main , idle or starter jet will lead to starting and running issues .

Fresh fuel normally unblockes them ,but normally they need a strip down, clean out the gum thats coats the bowl as the float can be stuck with fuel, and prick the jets with piano wire resemble with fresh gaskets , new fuel filter and flush crap out the tank and away you go .

Really depends on the carb sizes . Larger you will get away with it as the fuel itself or fresh added will wash away gum with bigger bore jets and the float bowl tolerance is greater so they are not stuck .

Injection ( the OP s case ) in another matter I guess the high pressure pump just blasts fuel through .

There might be sediments in the tank , but the pick up will not be at the bottom so they won’t be sucked up .
The fuel filter again will have latitude size wise to accommodate some restriction if there’s a bit of gum in that .
Also most modern engines stuffed with electrotwackery like this Vauxhall will have variable cam and other timing adjustment anti knock sensors etc so seamlessly can move between low octane and higher octane fuels .

I understand fresh fuel has additives ( which evaporate off or degrade down ) that lubricate the valve stems and build up a hardened surface on the valve seats themselves.The odd tank of crap fuel is irrelevant but constant running on old crap fuel will eventually take its toll .


As for the boat . DIESEL like Vas I found some 4 yr old diesel sitting in my “long range tank “ This was a added extra by the first owner a 600 L iirc separate tank with its own deck filler and cocked into the other two .
On the del trip we filled it .
Then I totally forgot to use it .
Some 4 yrs later I was in the ER looking at the sight glasses of the two main tanks and out of curiosity started to finger tap like piano playing the metal sides at the level .You could hear a distinct change in note below and above the mark on the glasses .
Then I saw the reserve like huge grey elephant, this has no glasses nor gauge on the dash .( I just have the two main 800 L tank gauges ) so I climbed over and started to tap it , piano finger it .Then double check the “ control “ and it sounded full ! Oh dear .
Didn’t know what to do with it .Forum was full of water in fuel , or black mould threads , VP common rail engines alarming off etc etc .
So I drained some off .

Left is from the 4 yr old sample first L , the RHS the next 2 ish litres .
Apart from the very bottom of the drain cock a bit cloudy the next 2 L looks fine .^

So I ran down the mains .Isolated them via the cocks and refilled the STb with the 4 y old all 600 L .Refilled the Port with fresh from the fuel dock / station ,
My thinking was if there was going to an issue I would still have one functioning engine .

We are none CR , Electronic injection but it’s only cylinder 1 that’s electronic the other 5 are normal conventional injectors relying on a computer algorithm and the measurements in the sensors on cyl 1 to work out the injection opening time etc That info is sent to the pump .

Plus we run racor primarys which centrifuge out water and the engine filters are 2 micron s .

As it happened it was all uneventful ….I did constantly 2x day drain off the racor but no water appeared .
I did pull both racors at the end of burning it up to compare the whiteness of the paper elements , and they looked identical- 4 yr vs fresh .

The issue with old diesel is condensation and the proliferation of micro organisms.
Not so much the combustion side as chip oil etc burns .