Arriving at Subic Bay on 3 November 1966, she operated in the Gulf of Tonkin and in coastal waters off North and South Vietnam in support of United States Seventh Fleet warships conducting operations in the Vietnam War, with Subic Bay as her base of operations. The summer of 1967 brought the oiler back to Long Beach for upkeep and U.S. West Coast operations until she again deployed to the Western Pacific on 5 January 1968 to assume support duties for Seventh Fleet forces off Vietnam. Through at least 1970, she continued to deploy to the Western Pacific for six to eight months of each year, spending the remainder operating out of Long Beach as part of Service Force, Pacific Fleet, in support of United States First Fleet operations and Fleet Training Group, San Diego, California.