The Wal-Marts here sometimes have Mobil 1 in the 5 quart jugs for $18, which would make it $3.60 per quart. When they don't have that special and it is in the one quart bottles it is $4.50 per quart.
Wal-Mart also has their own Supertech oil $4 for 5 quarts. They also have Castrol for just under $8 for 5 quarts.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record