Whisky Glenfiddich 18 Year Old. We use fine Spanish Oloroso wood and American oak to mature this rich, intriguingly fruity and robust oak expression, but there are many more reasons why this expression is special. Every batch is individually numbered and carefully watched over. Each has extra ordinary consistency and character from an intense marrying period, and a warming, distinguished finish. A truly exceptional single malt, the result not just of eighteen years of care and attention, but of whisky-making craft and knowledge passed down through the generations.