By Shay Castle, Boulder Daily Camera Bartkus Oil, a Boulder presence for 71 years, is going out of business this month, its demise hastened by the ongoing redevelopment of the city’s blue-collar bastions. There were a few factors that moved owner Steve Baxley to close the distributor of fuel and lubricants, only one of them related to the business: a shrinking customer base. Much of the decline came from shifting consumer tastes.