Average age (in years) of barrels used to make the classic Napa Valley chardonnay Stony Hill. (Their oldest barrels are more than 44 years old!). A majority of California wineries making high-end chardonnay consider brand new oak barrels imperative for flavor. Not Stony Hill. Since 1947 when Stony Hill began, it has purchased just 241 barrels. Most wineries would have purchased hundreds of thousands of barrels in the same time frame.