[WardL]

The octane of gasoline does not drop unless it is exposed to sunlight for several days or more. If your fuel is stored in a air tight container not exposed to a lot of light you are ok for at least a year. Most retail sites do blend premium and regular to make their midgrade. The State Weights and Measures people go around and measure the octane of gasoline. Call them up and ask how many low octane samples they find. It should be less than 10%. The low ones are usually due to a little regular gas getting into the premium.