sae 30 is okay to store the cylinder with it'll just smoke for a few minutes when you start it up again.
running a saw without a bar and chain will only hurt the engine if you run it full throttle for more than a minute[no load on the clutch,without the bar and chain its already moving faster.]
if you store yours with gas in the tank go to your local dealer or auto parts store and buy a product called sta-bil.it'll keep your gas fresh for a year.if you ned to clean your tank dump what you can out and fill the tank about half full and swish fuel mix around it that will usually clean it but you might have to use a blow gun with an air compressor to clean it.hope that helps.
