What is the shelf life of a drum of alchahol? I have about 15 gallons left from a drum I got last June.

Depends on how 'dry' you can keep it. it absorbs moisture and goes bad. If it smells like gasoline, its no good.

also if you do mix it with oil depending on if you race 270s its only about 2-3 week

It does not have oil mixed in for 270's. Has top end lube. Been in a plastic drum that I tighten lid as much as posible. Kept in my shop off the ground. Does not smell like gas. Thanks