Josh Reddick homered and had three RBIs for Oakland, which has a 3½ game lead over idle Texas in the American League West. It is Oakland's largest lead over the Rangers since Aug. 3. The teams are to scheduled play a three-game series this weekend in the Lone Star State.
Oswaldo Arcia homered for Minnesota, which has lost six of eight.
In winning his fourth straight start, Griffin (14-9) struck out eight and walked just one batter.
Making his first start since being recalled from Triple-A, Minnesota starter Scott Diamond (5-11) allowed five runs - four earned - in 4 2-3 innings.