Classic cars forum & vehicle restoration.

[norustplease]

I took my Traction out last week for a run, and found that initially at least, there was something of a lack of enthusiasm in the way it performed. Nothing that you could put down to a specific fault (it started second push on the button) but just not as lively as usual.
I sat and thought about it afterwards and wondered if it was down to old petrol. Probably like a lot of people, I filled up for a New Year's Day excursion, and then have hardly used the car since, certainly not enough to require a refill. The contents of my tank are therefore at least six months old. Likewise the 2CV was filled up just before lockdown in March and is still on half a tank!
I looked online for info.
The BP website says that in a sealed and sheltered tank, petrol is good for twelve months, so no problems there. Trouble is that our classic cars are not sealed tanks, they are probably only partially full, and most are vented to air in some way. The site goes on to say that equipment tanks (I assume this means chainsaws, lawn mowers, etc.) which have similarly primitive fuel systems, have only a life expectancy of a month, before they need pepping up with at least a 30% shot of new petrol. This is due to the evaporation of various key elements in the petrol.
So, if you filled up in March and then haven't used your car over much since (which most owners probably haven't) then your tank of petrol is likely to be distinctly lacking in bang by now.
Has anyone noticed an improvement after a refill recently? Obviously something to try if your classic is reluctant after its lockdown, before you start trying to pull it to pieces.
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1953 Citroen Traction
1964 Volvo PV544
1957 Austin A55 Mk 1
Boring Tucson SUV

[peter scott]

I can't say I've really noticed any difference with petrol that's been in the tank for 6 months. Perhaps my old car just eats anything.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Ray White]

[MVPeters]

Modern fuels apparently don't have the longer shelf life of older ones. If you can drain a little into a white cup, it should be perfectly clear, not yellow. Ideally, run the float bowl dry before storage.
You might enjoy this video, one of many. In almost every case he strips & cleans the carb. He has strong feelings about fuel stabilizers! Start at about 15:00
https://www.youtube.com/watch?v=lFsb0QLH8I0
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[alastairq]

Modern petrol also has different constituents, winter to summer [and the other two!!]

Winter petol is likely to get too hot for summer use[hot-starting issues]...

Get yourselves a copy of this book...it explains what goes on with today's petrol.

https://www.veloce.co.uk/store/Classic-Engines-Modern-Fuel-The-Problems-the-Solutions-p151478624

It is the results and conclusions of the tests conducted by Manchester University..using an old design engine [XPAG, as it happens].

It also explains what goes on with petrol throughout the year..and why sometimes our old cars struggle to cope with it.

The author[and test engineer] has been interviewed by one of the national papers regarding ethanol.....and blew away some of the urban myth surrounding the stuff.
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Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces.

[alanb]

My Morris 8 runs perfectly happy on 6 month old petrol, with 5 to 1 compression ratio anything above above 70 octane is useable, on the bright side for those worried about ethanol is that it evaporates faster than petrol so if left long enough you could end up with ethanol free fuel😃
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old tourer


Morris 8 two seater

[Keith D]

Maybe petrol out here differs from the UK stuff, but I've never noticed any problems from using old petrol. My only complaint is the truly appalling smell it produces when the engine is running on it.

Although our fuel composition differs between winter and summer, I've never experienced any difficulties starting through using old fuel. Probably because it doesn't get as cold as in the UK.

Keith
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1926 Chrysler 60 tourer
1932 Austin Seven RN long wheelbase box sedan
1950 Austin A40 tourer
1999 BMW Z3
Its weird being the same age as old people.
You are either part of the problem or part of the solution

[Rick]

[norustplease]

[norustplease]

The 2CV doesn't seem much bothered, but I will treat the Traction to a dose of new petrol and see how it feels about that.
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1953 Citroen Traction
1964 Volvo PV544
1957 Austin A55 Mk 1
Boring Tucson SUV

[MikeEdwards]

I recall reading somewhere (I thought it was on here, actually) that the first thing that goes "off" in modern petrol is one of the additives that aids starting. Hence you hear stories of people having trouble starting the car, spraying some "Easy Start" in the carbs to get it going, and then it running perfectly fine after that.

I try to make sure I run mine for a bit at least every month, to at least cycle the thermostat once. If it's dry enough, I'll take them for a short trip, but only one has done that recently.

[alastairq]

[nickjaxe]

My 1969 BSA Bantam does like fuel that much more than a month old....if my bike is going to be out of use for more than a month I drain the tank into a sealed container.

Ethanol is horrible stuff.
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http://www.youtube.com/watch?v=KbBlfYO46mI

My other hobby.

[alastairq]