Chris Denzer, a social worker who previously worked at the Pitchford Boys Ranch, has switched gears, so to speak. The longtime Roseburg resident recently launched The Oil Patrol, an on-site oil change and lube service."I've always had an interest in cars E It seemed like a pretty cool idea," he said of his new enterprise. The on-site concept for oil changes is "pretty big" on the East Coast, Denzer said."People can have me come to their house or their work and have me service their car and they don't have to take time out of their day to go have …