Chester-based Southside Oil LLC has bought 172 Exxon retail gasoline stations, mainly in Maryland, more than doubling the company’s retail operations. The privately held company did not disclose the terms of the sale. Southside Oil is a wholesale gasoline distribution company owned by Steven and Linda Uphoff. The Uphoffs also operate 42 Uppy’s Convenience Stores Inc. locations in Virginia. They own the property where 67 other BP and ExxonMobil gas stations are, but they don’t operate those stations.