Grenache should be served at room temperature. The more structured styles will benefit from being poured into a decanter and allowed to breathe for up to one hour before serving.
Most Grenache from France and Spain is meant to be consumed within two to six years of vintage date. New World Grenache is ready to drink upon release.
Buying (and drinking) an older bottle will typically get you a mellower wine with less obvious fruitiness and more pronounced spice box aromas. A younger wine will offer brighter, juicier fruit flavors and a firmer texture.
Store bottles in a cool, dark place. While it is now common for wine makers to use plastic corks or screw-top closures which may be stored vertically or horizontally, those with the traditional corks should be laid on their sides to keep them moist.