fuel stabilizer

[darrsi]

I still don't understand how petrol goes off? If it's sealed and not evaporating to any great amount, if it was 2 stroke then the oil ratio would increase if the petrol evaporated, my trike was unused for over 6 years and once I had got it started it ran perfectly, the reason it woudn't start was the the needle valve was stuck so no fuel was getting into the carb. I don't know if any additives are in petrol now or if its these that go off. Engines are hard to start if they have been stood.

http://www.voc.uk.com/net/docs/6.3/6.3-623-12.pdf