You may be surprised to learn that American oak actually plays a huge role in the production of Rioja wines. This practice actually has a long history dating back to the 1800s. Although it is a longstanding history as the traditional method for Rioja wines, in recent years the tradition has faded a little.
Rioja wines are almost all created by using a blend of different grapes but, generally speaking, the tempranillo grape is the MVP. Typically the tempranillo grape is the staple and makes up the majority of most Spanish wine Riojas. Tempranillo grape is then mixed with other grapes to achieve a certain desired flavor profile.