In the Southern Rhône, Grenache is most often blended with Syrah, Mourvèdre, and Cinsault.

Math is hard.

In Châteauneuf-du-Pape there are either thirteen or eighteen grapes allowed for blending. The math gets tricky since some of the red grapes have mutated, so they might count as two or three. (For the trivia minded, here they are: Cinsault, Counoise, Grenache Noir, Mourvèdre, Muscardin, Picpoul Noir, Syrah, Terret Noir, Vaccarèse, Bourboulenc, Clairette, Clairette Rose, Grenache Blanc, Grenache Gris, Picardan, Picpoul Blanc, Picpoul Gris, Roussanne.)