If you are traveling north to Cortez on 491, you can stop at the Ute Mountain Ute Casino's Truck stop (the diesel pumps are on the south side of the truck stop facility), on the west side of 160/491 about 15 miles south of Cortez. Closer to town, there are several stations that would accommodate you, including one on the NW corner of the 160/491 N junction at the east end of downtown Cortez. (You can access 491 N out of Cortez from both ends of town.) Monticello has several good options, as does Dove Creek, which is about halfway to Monticello on 491 N from Cortez.