Shelf Life of Unleaded Petrol

[mab01uk]

After 3 months winter break without a run had to drain replace my stale fuel at the weekend as it will never start on it in recent years after 3-6 months.........new fuel in tank and SU and it fired up first time.

Interesting write up on shelf life of modern petrol here (posted on MCR forum):
"The gradual elimination of Sulphur from fuel (not well publicised) has resulted in a lower shelf life for unleaded fuel. Oil companies surveyed estimated that a half full tank of unleaded could be unusable in as little as 2 months. Sulphur used to be added as a preservative to slow down algae growth in the fuel. Without it, the algae grow and the fuel quality deteriorates. How old is the fuel in your tank now?"

So yesterday, I phoned the BP Technical Support Line, and asked about the shelf life of unleaded fuel. “One month” I was told. “After one month in a half full fuel tank (ie: unsealed, plenty of air space) you would notice a drop in power. After three months, the car would be hard to start, would not idle well, and would suffer a significant loss of power. By this time, much of the high volatility elements in the fuel will have evaporated, leaving the more dense part of the mixture. In addition, the fuel will be oxidising and fungus will be growing. The fuel takes on an orange colour and gets progressively darker as time goes by.”

More:
http://www.spriteparts.com.au/tech/fuel.html

[66S]

Exacxtly what I was told some years ago. OK for a month and then progressively worse every month thereafter but noticelbly off at 3 months. Also, vapor-locking is much more likely with unleaded fuel.

Regards
Al

[formulaphoto]

I wonder how effective those fuel stabiliser additives are?

[mab01uk]

A couple of Mini owners have recommended this:
POR15 Fuel Preservative & Stabilizer
http://www.frost.co.uk/automotive-tanks ... -pint.html

[InimiaD]

I use a "Briggs & Stratton" fuel preserver. Put a shot of it in a Jerry can and use the fuel for all my garden toys, ride on, strimmer etc.
It seems to work insomuch that the garden toys start without any problems after the winter lay up even with last autumns fuel still in the system.
The preserver is also suitable for any unleaded petrol application.