Does fuel supplement go "off"?

I have found a 1 litre bottle of Flashlube in the spares crate that was given to me when I bought our beetle in 2013. It has been opened but very little has been used. They say petrol goes "off" after a few months, what about this stuff?
Thanks, Rob.

probably not as it would be oil based, assuming it is an upper cylinder lubricant right rather than an octane booster....

OK, what about Octane Booster?

lou0060 wrote:probably not as it would be oil based, assuming it is an upper cylinder lubricant right rather than an octane booster....

Thanks for that, I will check the bottle.
After I posted the topic I thought "well I could just buy another bottle", but I have always wondered if the lead replacements have a limited shelf life.
Cheers, Rob.